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Current Articles in the Latest JASN/CJASN

Journal of the American Society of Nephrology current issue

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This Month's Highlights

2012-01-01

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In Memoriam: Charles Bernard Carpenter

2012-01-01

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Bowman's {beta}-Catenin

2012-01-01

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Polarity and Renal Cystogenesis

2012-01-01

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Vasculitis Is an Antiangiogenic State

2012-01-01

No description available

Imperfect Gold Standards for Kidney Injury Biomarker Evaluation

2012-01-01

Clinicians have used serum creatinine in diagnostic testing for acute kidney injury for decades, despite its imperfect sensitivity and specificity. Novel tubular injury biomarkers may revolutionize the diagnosis of acute kidney injury; however, even if a novel tubular injury biomarker is 100% sensitive and 100% specific, it may appear inaccurate when using serum creatinine as the gold standard. Acute kidney injury, as defined by serum creatinine, may not reflect tubular injury, and the absence of changes in serum creatinine does not assure the absence of tubular injury. In general, the apparent diagnostic performance of a biomarker depends not only on its ability to detect injury, but also on disease prevalence and the sensitivity and specificity of the imperfect gold standard. Assuming that, at a certain cutoff value, serum creatinine is 80% sensitive and 90% specific and disease prevalence is 10%, a new perfect biomarker with a true 100% sensitivity may seem to have only 47% sensitivity compared with serum creatinine as the gold standard. Minimizing misclassification by using more strict criteria to diagnose acute kidney injury will reduce the error when evaluating the performance of a biomarker under investigation. Apparent diagnostic errors using a new biomarker may be a reflection of errors in the imperfect gold standard itself, rather than poor performance of the biomarker. The results of this study suggest that small changes in serum creatinine alone should not be used to define acute kidney injury in biomarker or interventional studies.

The Renal Manifestations of Thyroid Disease

2012-01-01

Thyroid hormones influence renal development, kidney structure, renal hemodynamics, GFR, the function of many transport systems along the nephron, and sodium and water homeostasis. These effects of thyroid hormone are in part due to direct renal actions and in part are mediated by cardiovascular and systemic hemodynamic effects that influence kidney function. As a consequence, both hypothyroidism and hyperthyroidism associate with clinically important alterations in kidney function and have relevance to its assessment. Disorders of thyroid function have also been linked to development of immune-mediated glomerular injury, and alterations in thyroid hormones and thyroid hormone testing occur in patients with kidney disease.

Notch Promotes Dynamin-Dependent Endocytosis of Nephrin

2012-01-01

Notch signaling in podocytes causes proteinuria and glomerulosclerosis in humans and rodents, but the underlying mechanism remains unknown. Here, we analyzed morphologic, molecular, and cellular events before the onset of proteinuria in newborn transgenic mice that express activated Notch in podocytes. Immunohistochemistry revealed a loss of the slit diaphragm protein nephrin exclusively in podocytes expressing activated Notch. Podocyte-specific deletion of Rbpj, which is essential for canonical Notch signaling, prevented this loss of nephrin. Overexpression of activated Notch decreased cell surface nephrin and increased cytoplasmic nephrin in transfected HEK293T cells; pharmacologic inhibition of dynamin, but not depletion of cholesterol, blocked these effects on nephrin, suggesting that Notch promotes dynamin-dependent, raft-independent endocytosis of nephrin. Supporting an association between Notch signaling and nephrin trafficking, electron microscopy revealed shortened podocyte foot processes and fewer slit diaphragms among the transgenic mice compared with controls. These data suggest that Notch signaling induces endocytosis of nephrin, thereby triggering the onset of proteinuria.

Antifibrotic Effect of Tamoxifen in a Model of Progressive Renal Disease

2012-01-01

Tamoxifen, a selective estrogen receptor modulator, has antifibrotic properties; however, whether it can attenuate renal fibrosis is unknown. In this study, we tested the effects of tamoxifen in a model of hypertensive nephrosclerosis (chronic inhibition of nitric oxide synthesis with L-NAME). After 30 days, treated rats had significantly lower levels of albuminuria as well as lower histologic scores for glomerulosclerosis and interstitial fibrosis than untreated controls. Tamoxifen was renoprotective despite having no effect on the sustained, severe hypertension induced by L-NAME. Tamoxifen prevented the accumulation of extracellular matrix by decreasing the expression of collagen I, collagen III, and fibronectin mRNA and protein. These renoprotective effects associated with inhibition of TGF-β1 and plasminogen activator inhibitor-1, and with a significant reduction in α-smooth muscle actin–positive cells in the renal interstitium. Furthermore, tamoxifen abrogated IL-1β– and angiotensin-II–induced proliferation of fibroblasts from both kidney explants and from the NRK-49F cell line. Tamoxifen also inhibited the expression of extracellular matrix components and the production and release of TGF-β1 into the supernatant of these cells. In summary, tamoxifen exhibits antifibrotic effects in the L-NAME model of hypertensive nephrosclerosis, likely through the inhibition of TGF-β1, suggesting that it may have therapeutic use in CKD treatment.

Anti-Neutrophil Cytoplasmic Antibodies Stimulate Release of Neutrophil Microparticles

2012-01-01

The mechanisms by which anti-neutrophil cytoplasmic antibodies (ANCAs) may contribute to the pathogenesis of ANCA-associated vasculitis are not well understood. In this study, both polyclonal ANCAs isolated from patients and chimeric proteinase 3–ANCA induced the release of neutrophil microparticles from primed neutrophils. These microparticles expressed a variety of markers, including the ANCA autoantigens proteinase 3 and myeloperoxidase. They bound endothelial cells via a CD18-mediated mechanism and induced an increase in endothelial intercellular adhesion molecule-1 expression, production of endothelial reactive oxygen species, and release of endothelial IL-6 and IL-8. Removal of the neutrophil microparticles by filtration or inhibition of reactive oxygen species production with antioxidants abolished microparticle-mediated endothelial activation. In addition, these microparticles promoted the generation of thrombin. In vivo, we detected more neutrophil microparticles in the plasma of children with ANCA-associated vasculitis compared with that in healthy controls or those with inactive vasculitis. Taken together, these results support a role for neutrophil microparticles in the pathogenesis of ANCA-associated vasculitis, potentially providing a target for future therapeutics.

Lineage Specification of Parietal Epithelial Cells Requires {beta}-Catenin/Wnt Signaling

2012-01-01

β-Catenin/Wnt signaling is essential during early inductive stages of kidney development, but its role during postinductive stages of nephron development and maturation is not well understood. In this study, we used Pax8Cre mice to target β-catenin deficiency to renal epithelial cells at the late S-shaped body stage and the developing collecting ducts. The conditional β-catenin knockout mice formed abnormal kidneys and had reduced renal function. The kidneys were hypoplastic with a thin cortex; a superficial layer of tubules was missing. A high proportion of glomeruli had small, underdeveloped capillary tufts. In these glomeruli, well differentiated podocytes replaced parietal epithelial cells in Bowman’s capsule; capillaries toward the outer aspect of these podocytes mimicked the formation of glomerular capillaries. Tracing nephrogenesis in embryonic conditional β-catenin knockout mice revealed that these "parietal podocytes" derived from precursor cells in the parietal layer of the S-shaped body by direct lineage switch. Taken together, these findings demonstrate that β-catenin/Wnt signaling is important during the late stages of nephrogenesis and for the lineage specification of parietal epithelial cells.

Clusterin Attenuates the Development of Renal Fibrosis

2012-01-01

Upregulation of clusterin occurs in several renal diseases and models of nephrotoxicity, but whether this promotes injury or is a protective reaction to injury is unknown. Here, in the mouse unilateral ureteral obstruction model, obstruction markedly increased the expression of clusterin, plasminogen activator inhibitor-1 (PAI-1), type I collagen, and fibronectin. Compared with wild-type mice, clusterin-deficient mice exhibited higher levels of PAI-1, type I collagen, and fibronectin and accelerated renal fibrosis in response to obstruction. In cultured rat tubular epithelium-like cells, adenovirus-mediated overexpression of clusterin inhibited the expression of TGF-β–stimulated PAI-1, type I collagen, and fibronectin. Clusterin inhibited TGF-β–stimulated Smad3 activity via inhibition of Smad3 phosphorylation and its nuclear translocation. Moreover, intrarenal delivery of adenovirus-expressing clusterin upregulated expression of clusterin in tubular epithelium-like cells and attenuated obstruction-induced renal fibrosis. In conclusion, clusterin attenuates renal fibrosis in obstructive nephropathy. These results suggest that upregulation of clusterin during renal injury is a protective response against the development of renal fibrosis.

Toll-Like Receptor 4 Promotes Tubular Inflammation in Diabetic Nephropathy

2012-01-01

Inflammation contributes to the tubulointerstitial lesions of diabetic nephropathy. Toll-like receptors (TLRs) modulate immune responses and inflammatory diseases, but their role in diabetic nephropathy is not well understood. In this study, we found increased expression of TLR4 but not of TLR2 in the renal tubules of human kidneys with diabetic nephropathy compared with expression of TLR4 and TLR2 in normal kidney and in kidney disease from other causes. The intensity of tubular TLR4 expression correlated directly with interstitial macrophage infiltration and hemoglobin A1c level and inversely with estimated glomerular filtration rate. The tubules also upregulated the endogenous TLR4 ligand high-mobility group box 1 in diabetic nephropathy. In vitro, high glucose induced TLR4 expression via protein kinase C activation in a time- and dose-dependent manner, resulting in upregulation of IL-6 and chemokine (C-C motif) ligand 2 (CCL-2) expression via IB/NF-B activation in human proximal tubular epithelial cells. Silencing of TLR4 with small interfering RNA attenuated high glucose–induced IB/NF-B activation, inhibited the downstream synthesis of IL-6 and CCL-2, and impaired the ability of conditioned media from high glucose–treated proximal tubule cells to induce transmigration of mononuclear cells. We observed similar effects using a TLR4-neutralizing antibody. Finally, streptozotocin-induced diabetic and uninephrectomized TLR4-deficient mice had significantly less albuminuria, renal dysfunction, renal cortical NF-B activation, tubular CCL-2 expression, and interstitial macrophage infiltration than wild-type animals. Taken together, these data suggest that a TLR4-mediated pathway may promote tubulointerstitial inflammation in diabetic nephropathy.

Reduced Expression of Lipoic Acid Synthase Accelerates Diabetic Nephropathy

2012-01-01

Oxidative stress contributes to the pathogenesis of diabetic nephropathy. In mitochondria, lipoic acid synthase produces α-lipoic acid, an antioxidant and an essential cofactor in α-ketoacid dehydrogenase complexes, which participate in glucose oxidation and ATP generation. Administration of lipoic acid abrogates diabetic nephropathy in animal models, but whether lower production of endogenous lipoic acid promotes diabetic nephropathy is unknown. Here, we crossed mice heterozygous for lipoic acid synthase deficiency (Lias+/–) with Ins2Akita/+ mice, a well characterized model of type 1 diabetes. Double mutant mice had more overt diabetic nephropathy, including microalbuminuria, glomerular basement thickening, mesangial matrix expansion, and hypertension, compared with Lias+/+Ins2Akita/+ controls. We also identified proximal tubules as a major site for generation of superoxide anions during diabetic nephropathy. Mitochondria in proximal tubular cells were particularly sensitive to damage in diabetic mice with reduced lipoic acid production. These results suggest that lipoic acid synthase deficiency increases oxidative stress and accelerates the development of diabetic nephropathy.

ErbB4 Modulates Tubular Cell Polarity and Lumen Diameter during Kidney Development

2012-01-01

ErbB4 receptor tyrosine kinase contributes to the development of the heart, the central nervous system, and the lactating mammary gland, but whether it has a role in the development of the kidney epithelium is unknown. Here, we found that expression of Erbb4 isoforms JM-a CYT-1 and JM-a CYT-2 was first detectable around embryonic day 13 in the mouse, mainly in the collecting ducts and both the proximal and distal tubules. In vitro, overexpression of a relevant ErbB4 isoform promoted proliferation and disturbed polarization of kidney epithelial cells when cultured as three-dimensional structures. We examined ErbB4 function in developing kidney tubules in vivo with Pax8-Cre–mediated conditional overexpression of Rosa26 locus–targeted ERBB4 and with conditional Erbb4 knock-out mice. The Pax8-Cre–driven ERBB4 overexpression enhanced proliferation in the collecting ducts, reduced the size of epithelial duct lumens, and promoted formation of cortical tubular cysts. These defects were associated with changes in the subcellular distribution of markers of epithelial cell polarity. Similarly, the Pax8-Cre–mediated Erbb4 knock-out mice manifested dysfunctional kidneys with larger duct lumens and epithelial cell mispolarization. Taken together, these data suggest that ErbB4 signaling modulates proliferation and polarization, cellular functions critical for the development of epithelial ducts in the kidney.

Sulodexide Fails to Demonstrate Renoprotection in Overt Type 2 Diabetic Nephropathy

2012-01-01

Sulodexide, a mixture of naturally occurring glycosaminoglycan polysaccharide components, has been reported to reduce albuminuria in patients with diabetes, but it is unknown whether it is renoprotective. This study reports the results from the randomized, double-blind, placebo-controlled, sulodexide macroalbuminuria (Sun-MACRO) trial, which evaluated the renoprotective effects of sulodexide in patients with type 2 diabetes, renal impairment, and significant proteinuria (>900 mg/d) already receiving maximal therapy with angiotensin II receptor blockers. The primary end point was a composite of a doubling of baseline serum creatinine, development of ESRD, or serum creatinine ≥6.0 mg/dl. We planned to enroll 2240 patients over approximately 24 months but terminated the study after enrolling 1248 patients. After 1029 person-years of follow-up, we did not detect any significant differences between sulodexide and placebo; the primary composite end point occurred in 26 and 30 patients in the sulodexide and placebo groups, respectively. Side effect profiles were similar for both groups. In conclusion, these data do not suggest a renoprotective benefit of sulodexide in patients with type 2 diabetes, renal impairment, and macroalbuminuria.

Pyridorin in Type 2 Diabetic Nephropathy

2012-01-01

Pyridoxamine dihydrochloride (Pyridorin, NephroGenex) inhibits formation of advanced glycation end products and scavenges reactive oxygen species and toxic carbonyls, but whether these actions translate into renoprotective effects is unknown. In this double-blind, randomized, placebo-controlled trial, we randomly assigned 317 patients with proteinuric type 2 diabetic nephropathy to twice-daily placebo; Pyridorin, 150 mg twice daily; or Pyridorin, 300 mg twice daily, for 52 weeks. At baseline, the mean age ± SD was 63.9±9.5 years, and the mean duration of diabetes was 17.6±8.5 years; the mean serum creatinine level was 2.2±0.6 mg/dl, and the mean protein-to-creatinine ratio was 2973±1932 mg/g. Regarding the primary end point, a statistically significant change in serum creatinine from baseline to 52 weeks was not evident in either Pyridorin group compared with placebo. However, analysis of covariance suggested that the magnitude of the treatment effect differed by baseline renal function. Among patients in the lowest tertile of baseline serum creatinine concentration, treatment with Pyridorin associated with a lower average change in serum creatinine concentration at 52 weeks (0.28, 0.07, and 0.14 mg/dl for placebo, Pyridorin 150 mg, and Pyridorin 300 mg, respectively; P=0.05 for either Pyridorin dose versus placebo); there was no evidence of a significant treatment effect in the middle or upper tertiles. In conclusion, this trial failed to detect an effect of Pyridorin on the progression of serum creatinine at 1 year, although it suggests that patients with less renal impairment might benefit.

A Clinicopathologic Study of Thrombotic Microangiopathy in IgA Nephropathy

2012-01-01

Thrombotic microangiopathy (TMA) occurs in IgA nephropathy, but its clinical significance is not well described. We retrospectively examined a series of 128 patients diagnosed with IgA nephropathy between 2002 and 2008 who had a mean follow-up of 44±27 months. In our series, 53% presented with lesions of TMA, acute or organized, in arteries and/or arterioles. Among patients with TMA, 4% were normotensive, 25% had controlled hypertension, and 71% had uncontrolled hypertension. Of those with uncontrolled hypertension, 26% had malignant hypertension. Histologically, the group with TMA had a significantly greater percentage of sclerotic glomeruli and worse tubulointerstitial fibrosis than those of the group without TMA. However, a significant minority of patients had near-normal histology, with minimal tubular atrophy (20%) and/or <20% interstitial fibrosis (24%). TMA rarely occurred in the absence of significant proteinuria. During follow-up, a doubling of serum creatinine or ESRD occurred in all patients with laboratory evidence of TMA, in 42% of those with morphologic evidence but no laboratory evidence of TMA, and in 11% of those without TMA. In summary, lesions of TMA are frequent in IgA nephropathy and may occur in normotensive patients with near-normal renal histology. Although the pathophysiologic mechanisms involved remain undetermined, the current study rules out severe hypertension or advanced renal disease as sole causes.

Segmental and Global Subclasses of Class IV Lupus Nephritis Have Similar Renal Outcomes

2012-01-01

Whether renal outcomes differ between the segmental and global subclasses of diffuse proliferative (class IV) lupus nephritis is unknown. In this meta-analysis, we searched the literature in MEDLINE, EMBASE, five registries of clinical trials, and selected cohort studies and randomized, controlled trials that used the 2003 International Society of Nephrology and Renal Pathology Society classification of lupus nephritis in adult patients. Our endpoint was the composite of doubling of serum creatinine concentration or ESRD. In the eight studies included in the final analysis, the incidence of this endpoint varied between 0% and 67%. A funnel plot and Egger's test did not suggest significant heterogeneity. The meta-analysis did not support a significant difference in renal outcome between the segmental (IV-S) and global (IV-G) subclasses (relative risk for class IV-G versus IV-S, 1.08; 95% confidence interval, 0.68–1.70). Meta-regression did not suggest that ethnicity or duration of follow-up influenced the association between histologic class and renal risk. In conclusion, the rate of doubling of serum creatinine concentration or of ESRD did not differ between patients with class IV-S and those with IV-G lupus nephritis.

Elevated Soluble Flt1 Inhibits Endothelial Repair in PR3-ANCA-Associated Vasculitis

2012-01-01

Antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis exhibits endothelial damage, but the capacity for vessel repair in this disorder is not well understood. Here, we observed a marked increase in serum levels of soluble Flt1 (sFlt1), a potent inhibitor of vascular endothelial growth factor, in patients with active ANCA-associated vasculitis compared with patients during remission and other controls. Serum levels of sFlt1 correlated with C5a, an anaphylatoxin released after complement activation. Serum from patients with acute ANCA-associated vasculitis disrupted blood flow in the chicken chorioallantoic membrane assay, suggesting an antiangiogenic effect. Preincubation with excess human vascular endothelial growth factor prevented this effect. Anti–proteinase-3 (PR3) mAb and serum containing PR3-ANCA from patients with active vasculitis both induced a significant and sustained release of sFlt1 from monocytes, whereas anti-myeloperoxidase (MPO) mAb or polyclonal antibodies did not. However, the serum containing polyclonal PR3-ANCA did not induce release of sFlt1 from cultured human umbilical vein endothelial cells. In summary, these data suggest that anti-PR3 antibodies, and to a much lesser extent anti-MPO antibodies, increase sFlt1 during acute ANCA-associated vasculitis, leading to an antiangiogenic state that hinders endothelial repair.

Sodium Intake, ACE Inhibition, and Progression to ESRD

2012-01-01

High sodium intake limits the antihypertensive and antiproteinuric effects of angiotensin-converting enzyme (ACE) inhibitors in patients with CKD; however, whether dietary sodium also associates with progression to ESRD is unknown. We conducted a post hoc analysis of the first and second Ramipril Efficacy in Nephropathy trials to evaluate the association of sodium intake with proteinuria and progression to ESRD among 500 CKD patients without diabetes who were treated with ramipril (5 mg/d) and monitored with serial 24-hour urinary sodium and creatinine measurements. Urinary sodium/creatinine excretion defined low (<100 mEq/g), medium (100 to <200 mEq/g), and high (≥200 mEq/g) sodium intake. During a follow-up of >4.25 years, 92 individuals (18.4%) developed ESRD. Among those with low, medium, and high sodium intakes, the incidence of ESRD was 6.1 (95% confidence interval [95% CI], 3.8–9.7), 7.9 (95% CI, 6.1–10.2), and 18.2 (95% CI, 11.3–29.3) per 100 patient-years, respectively (P<0.001). Patients with high dietary sodium exhibited a blunted antiproteinuric effect of ACE inhibition despite similar BP among groups. Each 100-mEq/g increase in urinary sodium/creatinine excretion associated with a 1.61-fold (95% CI, 1.15–2.24) higher risk for ESRD; adjusting for baseline proteinuria attenuated this association to 1.38-fold (95% CI, 0.95–2.00). This association was independent from BP but was lost after adjusting for changes in proteinuria. In summary, among patients with CKD but without diabetes, high dietary salt (>14 g daily) seems to blunt the antiproteinuric effect of ACE inhibitor therapy and increase the risk for ESRD, independent of BP control.

Immune Profile of Pediatric Renal Transplant Recipients following Alemtuzumab Induction

2012-01-01

The incidence of developing circulating anti-human leukocyte antigen antibodies and the kinetics of T cell depletion and recovery among pediatric renal transplant recipients who receive alemtuzumab induction therapy are unknown. In a collaborative endeavor to minimize maintenance immunosuppression in pediatric renal transplant recipients, we enrolled 35 participants from four centers and treated them with alemtuzumab induction therapy and a steroid-free, calcineurin-inhibitor–withdrawal maintenance regimen. At 3 months after transplant, there was greater depletion of CD4+ than CD8+ T cells within the total, naive, memory, and effector memory subsets, although depletion of the central memory subset was similar for CD4+ and CD8+ cells. Although CD8+ T cells recovered faster than CD4+ subsets overall, they failed to return to pretransplant levels by 24 months after transplant. There was no evidence for greater recovery of either CD4+ or CD8+ memory cells than naïve cells. Alemtuzumab relatively spared CD4+CD25+FoxP3+ regulatory T cells, resulting in a rise in their numbers relative to total CD4+ cells and a ratio that remained at least at pretransplant levels throughout the study period. Seven participants (20%) developed anti-human leukocyte antigen antibodies without adversely affecting allograft function or histology on 2-year biopsies. Long-term follow-up is underway to assess the potential benefits of this regimen in children.

Clinical Journal of the American Society of Nephrology current issue

Clinical Journal of the American Society of Nephrology RSS feed -- current issue

CJASN--One Year Later

2012-01-01

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A New CJASN Feature: CJASN's eJournal Club (eJC)

2012-01-01

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Dialysate Sodium and the Milieu Interieur

2012-01-01

No description available

Are Surrogate Assumptions and Use of Diuretics Associated with Diagnosis and Staging of Acute Kidney Injury after Cardiac Surgery?

2012-01-01

Background and objectives

This study measured the association between the Acute Kidney Injury Network (AKIN) diagnostic and staging criteria and surrogates for baseline serum creatinine (SCr) and body weight, compared urine output (UO) with SCr criteria, and assessed the relationships between use of diuretics and calibration between criteria and prediction of outcomes.

Design, setting, participants, & measurements

This was a retrospective cohort study using prospective measurements of SCr, hourly UO, body weight, and drug administration records from 5701 patients admitted, after cardiac surgery, to a cardiac intensive care unit between 1995 and 2006.

Results

More patients (n=2424, 42.5%) met SCr diagnostic criteria with calculated SCr assuming a baseline estimated GFR of 75 ml/min per 1.73 m2 than with known baseline SCr (n=1043, 18.3%). Fewer patients (n=484, 8.5%) met UO diagnostic criteria with assumed body weight (70 kg) than with known weight (n=624, 10.9%). Agreement between SCr and UO criteria was fair (=0.28; 95% confidence interval 0.25–0.31). UO diagnostic criteria were specific (0.95; 0.94–0.95) but insensitive (0.36; 0.33–0.39) compared with SCr. Intravenous diuretics were associated with higher probability of falling below the UO diagnostic threshold compared with SCr, higher 30-day mortality (relative risk, 2.27; 1.08–4.76), and the need for renal support (4.35; 1.82–10.4) compared with no diuretics.

Conclusions

Common surrogates for baseline estimated GFR and body weight were associated with misclassification of AKIN stage. UO criteria were insensitive compared with SCr. Intravenous diuretic use further reduced agreement and confounded association between AKIN stage and 30-day mortality or need for renal support.

Adding Specialized Clinics for Remote-Dwellers with Chronic Kidney Disease: A Cost-Utility Analysis

2012-01-01

Background and objectives

This study aimed to determine whether opening a new clinic in a remote region would be a cost-effective means of improving care for remote-dwellers with CKD.

Design, setting, participants, & measurements

This study is a cost-utility analysis from a public payer’s perspective over a lifetime horizon, using administrative data from a large cohort of adults with stage 3b-4 CKD in Alberta, Canada. The association between the distance from each simulated patient’s residence and the practice location of the closest nephrologist and clinical outcomes (quality of care, hospitalization, dialysis, and death) were examined. A Markov 6-month cycle economic decision model was analyzed; estimates of the effect of a new clinic were based on the association between residence location, resource use, and outcomes. Costs are reported in 2009 Canadian dollars.

Results

The costs for equipping and operating a clinic for 321 remote-dwelling patients were estimated at $25,000 and $250,000/yr, respectively. The incremental cost-utility ratios (ICURs) ranged from $4000 to $8000/quality-adjusted life-year under most scenarios. However, if reducing distance to nephrologist care does not alter mortality or hospitalization among remote-dwellers, the cost-effectiveness becomes less attractive. All other one-way sensitivity analyses had negligible effects on the ICUR.

Conclusions

Given the low costs of equipping and operating new clinics, and the very attractive ICUR relative to other currently funded interventions, establishing new clinics for remote-dwellers could play an important role in efficiently improving outcomes for patients with CKD. High-quality controlled studies are required to confirm this hypothesis.

Timing and Determinants of Erythropoietin Deficiency in Chronic Kidney Disease

2012-01-01

Background and objectives

Anemia in patients with CKD is highly related to impaired erythropoietin (EPO) response, the timing and determinants of which remain unknown.

Design, setting, participants, & measurements

This study measured EPO levels and studied their relation to GFR measured by 51Cr-EDTA renal clearance (mGFR) in 336 all-stage CKD patients not receiving any erythropoiesis-stimulating agent.

Results

In patients with anemia defined by World Health Organization criteria (hemoglobin [Hb] <13 g/dl in men and 12 g/dl in women), EPO response to Hb level varied by mGFR level. EPO and Hb levels were negatively correlated (r=–0.22, P=0.04) when mGFR was >30 ml/min per 1.73 m2, whereas they were not correlated when mGFR was <30 (r=0.09, P=0.3; P for interaction=0.01). In patients with anemia, the ratio of observed EPO to the level predicted by the equation for their Hb level decreased from 0.72 (interquartile range, 0.57–0.95) for mGFR ≥60 ml/min per 1.73 m2 to 0.36 (interquartile range, 0.16–0.69) for mGFR <15. Obesity, diabetes with nephropathy other than diabetic glomerulopathy, absolute iron deficiency, and high C-reactive protein concentrations were associated with increased EPO levels, independent of Hb and mGFR.

Conclusions

Anemia in CKD is marked by an early relative EPO deficiency, but several factors besides Hb may persistently stimulate EPO synthesis. Although EPO deficiency is likely the main determinant of anemia in patients with advanced CKD, the presence of anemia in those with mGFR >30 ml/min per 1.73 m2 calls for other explanatory factors.

Venous Thromboembolism in Patients with Membranous Nephropathy

2012-01-01

Background and objectives

The aims of this study were to determine the frequency of venous thromboembolic events in a large cohort of patients with idiopathic membranous nephropathy and to identify predisposing risk factors.

Design, setting, participants, & measurements

We studied patients with biopsy-proven membranous nephropathy from the Glomerular Disease Collaborative Network (n=412) and the Toronto Glomerulonephritis Registry (n=486) inception cohorts. The cohorts were pooled after establishing similar baseline characteristics (total n=898). Clinically apparent and radiologically confirmed venous thromboembolic events were identified. Potential risk factors were evaluated using multivariable logistic regression models.

Results

Sixty-five (7.2%) subjects had at least one venous thromboembolic event, and this rate did not differ significantly between registries. Most venous thromboembolic events occurred within 2 years of first clinical assessment (median time to VTE = 3.8 months). After adjusting for age, sex, proteinuria, and immunosuppressive therapy, hypoalbuminemia at diagnosis was the only independent predictor of a venous thromboembolic event. Each 1.0 g/dl reduction in serum albumin was associated with a 2.13-fold increased risk of VTE. An albumin level <2.8 g/dl was the threshold below which risk for a venous thromboembolic event was greatest.

Conclusions

We conclude that clinically apparent venous thromboembolic events occur in about 7% of patients with membranous nephropathy. Hypoalbuminemia, particularly <2.8 g/dl, is the most significant independent predictor of venous thrombotic risk.

The Effect of High-Flux Hemodialysis on Hemoglobin Concentrations in Patients with CKD: Results of the MINOXIS Study

2012-01-01

Background and objectives

Hemodialysis treatment induces markers of inflammation and oxidative stress, which could affect hemoglobin levels and the response to erythropoietin use. This study sought to determine whether high-flux dialysis would help improve markers of renal anemia, inflammation, and oxidative stress compared with low-flux dialysis.

Design, settings, participants, & measurements

In a prospective, controlled study, 221 patients undergoing maintenance hemodialysis and receiving darbepoetin-alfa treatment (mean age, 66 years; 55% male) from 19 centers were screened in a 20-week run-in period of low-flux hemodialysis with a synthetic dialysis membrane. Thereafter, 166 patients were enrolled and randomly assigned to receive a synthetic high-flux membrane or to continue on low-flux dialysis for 52 weeks. Data on myeloperoxidase, oxidized LDL, high-sensitivity C-reactive protein, and the Malnutrition Inflammation Score were collected at baseline and after 52 weeks; routine laboratory data, such as hemoglobin, ferritin, and albumin, and the use of darbepoetin-alfa, were also measured in the run-in period.

Results

After 52 weeks, the low-flux and the high-flux groups did not differ with respect to hemoglobin (mean ± SD, 11.7±0.9 g/dl versus 11.7±1.1 g/dl; P=0.62) or use of darbepoetin-alfa (mean dosage ± SD, 29.8±24.8 μg/wk versus 26.0±31.1 μg/wk; P=0.85). Markers of inflammation, oxidative stress, or nutritional status also did not differ between groups.

Conclusion

Over 1 year, high-flux dialysis had no superior effects on hemoglobin levels or markers of inflammation, oxidative stress, and nutritional status. These data do not support the hypothesis that enhanced convective toxin removal would improve patient outcome.

The Effectiveness of Long-Term Agalsidase Alfa Therapy in the Treatment of Fabry Nephropathy

2012-01-01

Background and objectives

Fabry disease is a rare X-linked disease with multisystemic manifestations. This study investigated the effectiveness of long-term enzyme replacement therapy with agalsidase alfa in Fabry nephropathy treatment.

Design, setting, participants, & measurements

In this observational study, data on patients receiving agalsidase alfa (0.2 mg/kg every other week) were extracted from the Fabry Outcome Survey, an international registry of patients with Fabry disease. Serum creatinine and estimated GFR (eGFR) at baseline and after ≥5 years of treatment were assessed; 24-hour urinary protein excretion and BP measurements were also reviewed. The eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration formula. Patients with an eGFR <30 ml/min per 1.73 m2 were excluded.

Results

Renal function was assessed in 208 patients (mean enzyme replacement therapy, 7.4 years; range, 5.0–11.2 years). Mean yearly change in eGFR was –2.2 ml/min per 1.73 m2 in men and –0.7 ml/min per 1.73 m2 in women (95% confidence limits, –2.8; –1.7 and –1.4; 0.0, respectively). Patients with 24-hour protein excretion >1 g/24 h had poorer renal function at baseline and follow-up compared with patients with protein excretion of 500–1000 mg/24 h or with proteinuria <500 mg/24 h. Renal function was worse in patients with baseline arterial hypertension, and there was a more rapid yearly decline compared with normotensive patients.

Conclusions

This study suggests that long-term agalsidase alfa therapy is able to stabilize the rate of Fabry nephropathy progression in women and is associated with a mild to moderate decline of renal function in men.

Vascular Access Sites for Acute Renal Replacement in Intensive Care Units

2012-01-01

Background and objectives

Several temporary venous catheterizations are sometimes required for acute renal replacement therapy (RRT) in the intensive care unit (ICU). This study compares first and second catheterizations in the femoral and jugular veins in terms of patient safety.

Design, setting, participants, & measurements

A crossover study from the catheter-dialysis randomized study (Cathedia), which was conducted among 736 critically ill adults requiring RRT, was performed. Catheter insertion complications, catheter-tip colonization, catheter dysfunction and urea reduction ratio (URR) were analyzed considering the crossover and longitudinal designs.

Results

This study analyzed 134 patients who underwent two different sites of catheterization, 57 and 77 of whom were initially randomized in the femoral and jugular site, respectively. Using anatomic landmarks, time to insert a femoral catheter was shorter (P=0.01) and more successful (P=0.003) compared with catheterization in the jugular site. Time to catheter-tip colonization at removal was not significantly different between the two sites of insertion (median, 14 days in both groups; hazard ratio, 0.99; 95% confidence interval, 0.61–1.59; P=0.96), as well as time to dysfunction. URRs were analyzed from 395 dialysis sessions (n=48 patients). No significant difference (P=0.49) in mean URR was detected between sessions performed through femoral (n=213; 50.9%) and jugular (n=182; 49.5%) dialysis catheters.

Conclusions

These results validate prior results of this study group and extend external validity to the second catheter used for RRT in the ICU. Femoral and internal jugular acute vascular access sites are both acceptable for RRT therapy in the ICU.

Early Renal Function Decline in Type 2 Diabetes

2012-01-01

Background and objectives

Early decline in GFR may reflect progressive kidney disease in type 1 diabetes, but its predictive value in type 2 diabetes is uncertain.

Design, setting, participants, & measurements

In this longitudinal study, GFR was measured serially over approximately 4.0 years in 195 Pima Indians with type 2 diabetes. Renal function decline (RFD) was defined during this initial period by an average GFR loss ≥3.3%/yr, as defined previously in type 1 diabetes. Subsequently, participants were followed for up to 17.8 years to ESRD onset, death, or December 31, 2010, whichever came first.

Results

RFD prevalence during the initial period was 32% in 68 participants with normal baseline albuminuria (albumin/creatinine ratio [ACR] < 30 mg/g), 42% in 88 with microalbuminuria (ACR 30 to <300 mg/g), and 74% in 39 with macroalbuminuria (ACR ≥300 mg/g; P<0.001). The cumulative incidence of ESRD 10 years after the initial period was 41% in those with RFD and 15% in those without (P<0.001); 41 of the 49 ESRD cases (83.7%) occurred in participants who had or developed macroalbuminuria during the initial period. When adjusted for age, sex, diabetes duration, and hemoglobin A1c, the ESRD hazard rate was 4.78 times (95% confidence interval, 2.39–9.58) as high in those with RFD as in those without; further adjustment for albuminuria attenuated this association (hazard ratio, 1.79; 95% confidence interval, 0.82–3.91).

Conclusions

In type 2 diabetes, loss of GFR often occurs before the onset of macroalbuminuria, but a decline predictive of ESRD is strongly dependent on progression to macroalbuminuria.

Serum Fibroblast Growth Factor-23 and Risk of Incident Chronic Kidney Disease in Older Community-Dwelling Women

2012-01-01

Background and objectives

Elevated circulating fibroblast growth factor 23 (FGF23) predicts progression of CKD, but it is unknown whether circulating FGF23 independently predicts incident CKD. This study aimed to determine whether circulating FGF23 predicts incident CKD in community-dwelling women.

Design, setting, participants, & measurements

This study examined the relationship of intact serum FGF23, 1,25-dihydroxyvitamin D3 (1,25[OH]2D), 25-hydroxyvitamin D (25[OH]D), parathyroid hormone, calcium, and phosphate with prevalent and incident CKD in 701 disabled women, ≥65 years of age, from the Women’s Health and Aging Study I in Baltimore, Maryland, from 1993 to 1997. Incident CKD was defined as a low estimated GFR (eGFR) <60 ml/min per 1.73 m2 only, low eGFR <60 ml/min per 1.73 m2 and a ≥25% decline in eGFR from baseline, and an increase in serum creatinine (≥0.4 mg/dl) at follow-up.

Results

At baseline, 381 women (54.3%) had stage 3 CKD. Of 307 women without CKD at baseline, 63 (20.5%) developed stage 3 CKD over 24 months of follow-up. After excluding prevalent cases of CKD, FGF23 (per 1 SD increase) was associated with incident stage 3 CKD (hazard ratio [HR], 1.51; 95% confidence interval [95% CI], 1.06, 2.16; P=0.02), low and declining eGFR (HR, 3.69; 95% CI, 1.68, 8.11; P=0.001), and increase in serum creatinine (HR, 5.35; 95% CI, 1.27, 22.54; P=0.02) in respective multivariable Cox proportional hazards models adjusting for baseline eGFR, age, race, phosphate, 1,25-dihydroxyvitamin D3, parathyroid hormone, and other potential confounders.

Conclusions

Elevated FGF23 is an independent risk factor for incident CKD in older, disabled, community-dwelling women.

Dialysate Sodium Concentration and the Association with Interdialytic Weight Gain, Hospitalization, and Mortality

2012-01-01

Background and objectives

Recommendations to decrease the dialysate sodium (DNa) prescription demand analyses of patient outcomes. We analyzed morbidity and mortality at various levels of DNa, simultaneously accounting for interdialytic weight gain (IDWG) and for the mortality risk associated with lower predialysis serum sodium (SNa) levels.

Design, setting, participants, & measurements

We used multiply-adjusted linear mixed models to evaluate the magnitude of IDWG and Cox proportional hazards models to assess hospitalizations and deaths in 29,593 patients from the Dialysis Outcomes and Practice Patterns Study with baseline DNa and SNa as predictors, categorized according to lowest to highest levels.

Results

IDWG increased with higher DNa across all SNa categories, by 0.17% of body weight per 2 mEq/L higher DNa; however, higher DNa was not associated with higher mortality in a fully adjusted model (also adjusted for SNa; hazard ratio [HR]=0.98 per 2 mEq/L higher DNa, 95% confidence interval [CI] 0.95–1.02). Instead, higher DNa was associated with lower hospitalization risk (HR=0.97 per 2 mEq/L higher DNa, 95% CI 0.95–1.00, P=0.04). Additional adjustments for IDWG did not change these results. In sensitivity analyses restricted to study facilities, in which 90%–100% of patients have the same DNa (56%), the adjusted HR for mortality was 0.88 per 2 mEq/L higher DNa (95% CI 0.83–0.94). These analyses represented a pseudo-randomized experiment in which the association between DNa and mortality is unlikely to have been confounded by indication.

Conclusions

In the absence of randomized prospective studies, the benefit of reducing IDWG by decreasing DNa prescriptions should be carefully weighed against an increased risk for adverse outcomes.

Racial Differences in the Incidence of Chronic Kidney Disease

2012-01-01

Background and objectives

The incidence of ESRD is higher in African Americans than in whites, despite reports of a similar or lower prevalence of CKD.

Design, setting, participants, & measurements

This study compared the incidence of CKD among young African-American and white adults over 20 years of follow-up in the community-based Coronary Artery Risk Development in Young Adults study. Participants included 4119 adults, 18–30 years of age, with an estimated GFR (eGFR) ≥60 ml/min per 1.73 m2 at baseline. Incident CKD was defined as an eGFR <60 ml/min per 1.73 m2 and a ≥25% decline in eGFR at study visits conducted 10, 15, and 20 years after baseline.

Results

At baseline, the mean age of African Americans and whites was 24 and 26 years, respectively (P<0.001), and 56% and 53% of participants, respectively, were women (P=0.06). There were 43 incident cases of CKD during follow-up, 29 (1.4%) among African Americans and 14 (0.7%) among whites (P=0.02). The age- and sex-adjusted hazard ratio (HR) for incident CKD comparing African Americans to whites was 2.56 (95% confidence interval [95% CI], 1.35–5.05). After further adjustment for body mass index, systolic BP, fasting plasma glucose, and HDL cholesterol, the HR was 2.51 (95% CI, 1.25–5.05). After multivariable adjustment including albuminuria at year 10, the HR for CKD at year 15 or 20 was 1.12 (95% CI, 0.52–2.41).

Conclusions

In this study, the 20-year CKD incidence was higher among African Americans than whites, a difference that is explained in part by albuminuria.

Seasonal Variations in Mortality, Clinical, and Laboratory Parameters in Hemodialysis Patients: A 5-Year Cohort Study

2012-01-01

Background and objectives

Mortality varies seasonally in the general population, but it is unknown whether this phenomenon is also present in hemodialysis patients with known higher background mortality and emphasis on cardiovascular causes of death. This study aimed to assess seasonal variations in mortality, in relation to clinical and laboratory variables in a large cohort of chronic hemodialysis patients over a 5-year period.

Design, setting, participants, & measurements

This study included 15,056 patients of 51 Renal Research Institute clinics from six states of varying climates in the United States. Seasonal differences were assessed by chi-squared tests and univariate and multivariate cosinor analyses.

Results

Mortality, both all-cause and cardiovascular, was significantly higher during winter compared with other seasons (14.2 deaths per 100 patient-years in winter, 13.1 in spring, 12.3 in autumn, and 11.9 in summer). The increase in mortality in winter was more pronounced in younger patients, as well as in whites and in men. Seasonal variations were similar across climatologically different regions. Seasonal variations were also observed in neutrophil/lymphocyte ratio and serum calcium, potassium, and platelet values. Differences in mortality disappeared when adjusted for seasonally variable clinical parameters.

Conclusions

In a large cohort of dialysis patients, significant seasonal variations in overall and cardiovascular mortality were observed, which were consistent over different climatic regions. Other physiologic and laboratory parameters were also seasonally different. Results showed that mortality differences were related to seasonality of physiologic and laboratory parameters. Seasonal variations should be taken into account when designing and interpreting longitudinal studies in dialysis patients.

Improving Ascertainment of Sudden Cardiac Death in Patients with End Stage Renal Disease

2012-01-01

Background and objectives

Data collected by the US Renal Data System (USRDS) identify sudden cardiac death (SCD) as the leading cause of death among hemodialysis patients. However, evidence suggests that clinical events captured on the USRDS death notification form may be inaccurate. A new method for classifying SCD was recently developed to enhance the accuracy of SCD classification. This study examined the performance characteristics of this refined definition using a cohort of hemodialysis patients who experienced a witnessed SCD as the reference standard.

Design, setting, participants, & measurements

This is a retrospective cohort study of 363 patients who experienced a witnessed SCD in US Gambro (DaVita) outpatient dialysis clinics. Sensitivity of SCD defined by death notification forms and SCD defined using additional administrative sources was compared. Clinical data recorded near time of death were also examined.

Results

Existing USRDS death notification forms reported 70.8% of witnessed SCD as "cardiac arrest/cause unknown" or "arrhythmia." The refined definition significantly improved identification to 83.8% of witnessed SCD events (P<0.001). Verified SCD cases that were not identified by either definition were more likely to be reported on the death notification form as death due to myocardial infarction, hyperkalemia, sepsis, malignancy, or unknown cause.

Conclusions

Compared with the death notification form alone, the refined SCD definition significantly improves the sensitivity of reporting of witnessed SCD occurring within outpatient hemodialysis clinics. More accurate reporting of cardiac events by clinicians and refinements to existing death notification forms may further improve recognition and understanding of SCD.

Predictors of Sudden Cardiac Death: A Competing Risk Approach in the Hemodialysis Study

2012-01-01

Background and objectives

There are few data on risk factors for sudden cardiac death (SCD) in patients undergoing hemodialysis (HD). The study objective was to identify predictors associated with various causes of death in the Hemodialysis (HEMO) Study and to develop a prediction model for SCD using a competing risk approach.

Design, setting, participants, & measurements

In this analysis of 1745 HEMO participants, all-cause mortality was classified as SCD, non-SCD, and noncardiac death. Predictors for each cause of death were evaluated using cause-specific Cox proportional hazards models, and a competing risk approach was used to calculate absolute risk predictions for SCD.

Results

During a median follow-up of 2.5 years, 808 patients died. Rates of SCD, non-SCD, and noncardiac death were 22%, 17%, and 61%, respectively. Predictors of various causes of death differ somewhat in HD patients. Age, diabetes, peripheral vascular disease, ischemic heart disease, serum creatinine, and alkaline phosphatase were independent predictors of SCD. The 3-year C-statistic for SCD was 0.75 (95% confidence interval, 0.70–0.79), and calibration was good (2=1.1; P=0.89). At years 3 and 5 of follow-up, the standard Cox model overestimated the risk for SCD as compared with the competing risk approach on the relative scale by 25% and 46%, respectively, and on the absolute scale by 2% and 6%, respectively.

Conclusions

Predictors of various causes of death differ in HD patients. The proposed prediction model for SCD accounts for competing causes of death. External validation of this model is required.

Baseline Levels and Trimestral Variation of Triiodothyronine and Thyroxine and Their Association with Mortality in Maintenance Hemodialysis Patients

2012-01-01

Background and objectives

Conflicting evidence exists with regard to the association of thyroid hormones and mortality in dialysis patients. This study assesses the association between basal and trimestral variation of thyroid stimulating hormone, triiodothyronine, and thyroxine and mortality.

Design, setting, participants, & measurements

In 210 prevalent hemodialysis patients, serum triiodothyronine, thyroxine, thyroid stimulating hormone, and interleukin-6 were measured 3 months apart. Cardiovascular and non-cardiovascular deaths were registered during follow-up. Based on fluctuations along tertiles of distribution, four trimestral patterns were defined for each thyroid hormone: persistently low, decrease, increase, and persistently high. The association of baseline levels and trimestral variation with mortality was investigated with Kaplan–Meier curves and Cox proportional hazard models.

Results

During follow-up, 103 deaths occurred. Thyroid stimulating hormone levels did not associate with mortality. Patients with relatively low basal triiodothyronine concentrations had higher hazards of dying than patients with high levels. Longitudinally, patients with persistently low levels of triiodothyronine during the 3-month period had higher mortality hazards than those having persistently high levels. These associations were mainly attributable to cardiovascular-related mortality. The association between thyroxine and mortality was not altered after adjustment for triiodothyronine.

Conclusions

Hemodialysis patients with reduced triiodothyronine or thyroxine levels bear an increased mortality risk, especially due to cardiovascular causes. This was true when considering both baseline measurements and trimestral variation patterns. Our longitudinal design adds observational evidence supporting the hypothesis that the link may underlie a causal effect.

(1-34) Parathyroid Hormone Infusion Acutely Lowers Fibroblast Growth Factor 23 Concentrations in Adult Volunteers

2012-01-01

Background and objectives

Fibroblast growth factor 23 (FGF23) regulates phosphorus and vitamin D metabolism. Parathyroid hormone (PTH) infusion for 24 hours stimulated FGF23 secretion in healthy volunteers. The extent to which this was due to a direct stimulatory effect of PTH versus an indirect effect of increasing 1,25-dihydroxyvitamin D [1,25(OH)2D] levels was unclear.

Design, setting, participants, & measurements

Changes in FGF23 in 26 adults undergoing 6-hour (1-34) PTH infusion were examined, focusing particularly on the effects of PTH on FGF23 in the early period of infusion before sustained increases in 1,25(OH)2D.

Results

FGF23 levels declined in parallel with serum phosphate during infusion (P<0.05 for both), with both analytes decreasing within the first hour and reaching their respective nadirs at 6 hours. These changes were observed despite no change in 1,25(OH)2D levels during the first hour and a significant increase in 1,25(OH)2D from baseline after 6 hours (P<0.001). There were no differences in these responses by race. However, modest racial differences in the phosphaturic response to (1-34) PTH were observed (P=0.04 for interaction), with a higher rate of increase in fractional phosphate excretion in blacks than in whites.

Conclusions

During short-term (1-34) PTH infusion, FGF23 levels decreased in parallel with serum phosphate levels and despite significant increases in 1,25(OH)2D. When coupled with the results of prior longer-term infusion studies, these findings suggest that acute increases in PTH initially act to suppress FGF23 secretion, perhaps to mitigate urinary phosphate losses, before the stimulatory effect of 1,25(OH)2D on FGF23 eventually begins to predominate.

Early Skeletal and Biochemical Alterations in Pediatric Chronic Kidney Disease

2012-01-01

Background and objectives

The relationship between parathyroid hormone, fibroblast growth factor 23 (FGF-23), and indices of bone turnover and mineralization in children with early CKD is unknown; thus, this study characterizes the features of renal osteodystrophy and their relationship to biochemical markers of mineral metabolism.

Design, setting, participants, & measurements

Fifty-two patients 2–21 years of age with predialysis CKD underwent tetracycline-labeled bone biopsy. Anthropomorphic measurements and biochemical values were obtained at the time of biopsy.

Results

Serum phosphorus levels were increased in 4% of patients with stage 3 CKD and 43% of those with stage 4/5 CKD. Parathyroid hormone concentrations were elevated in 36% of patients with stage 2, 71% with stage 3, and 93% with stage 4/5 CKD, whereas FGF-23 values were elevated in 81% of all patients, regardless of CKD stage. Bone turnover was normal in all patients with stage 2, but was increased in 13% with stage 3 and 29% with stage 4/5 CKD. Defective mineralization was present in 29% of patients with stage 2, 42% with stage 3, and 79% with stage 4/5 CKD. Defective skeletal mineralization was associated with lower serum calcium levels and increased parathyroid hormone concentrations.

Conclusions

Elevated circulating FGF-23 levels and defects in skeletal mineralization early in the course of CKD suggest that factors other than the traditional markers of mineral deficiency play a crucial role in the development of renal bone disease.

Does Allograft Failure Impact Infection Risk on Peritoneal Dialysis: A North American Pediatric Renal Trials and Collaborative Studies Study

2012-01-01

Background and objectives

Several adult studies report that patients returning to peritoneal dialysis after allograft failure have increased infection-related morbidity. The impact of allograft failure on infection risk in children is uncertain. We compared peritonitis-free survival between pediatric peritoneal dialysis patients with prior allograft failure and those who were transplant naive.

Design, setting, participants, & measurements

We studied patients, 2–21 years of age, who initiated peritoneal dialysis from January 1, 1992, to December 31, 2007, in the North American Pediatric Renal Trials and Collaborative Studies registry. Demographic characteristics were compared between transplant naive and allograft failure patients using a chi-squared statistic. Peritonitis-free survival was compared between the two groups using Kaplan–Meier estimates. A Cox regression analysis was performed to adjust for covariates, which impact risk of peritonitis.

Results

Of 2829 patients on peritoneal dialysis, 445 had a prior history of allograft failure and 2384 did not (transplant naive). Demographic characteristics including age at dialysis initiation, race, primary renal disease, and era of dialysis initiation were significantly different between the two groups. Peritonitis-free survival was poorer for the allograft failure group. After covariate adjustment, allograft failure showed borderline significance as a factor predictive of peritonitis.

Conclusions

Children initiating peritoneal dialysis after allograft failure may experience a slightly higher infection risk.

The Influence of Induction Therapy for Kidney Transplantation after a Non-Renal Transplant

2012-01-01

Background and objectives

Non-renal transplant recipients who subsequently develop ESRD and undergo kidney transplantation are medically and immunologically complex due to comorbidities, high cumulative exposure to immunosuppressants, and sensitization to alloantigen from the prior transplant. Although prior non-renal transplant recipients are one of the fastest growing segments of the kidney wait list, minimal data exist to guide the use of antibody induction therapy (IT+) at the time of kidney after lung (KALu), heart (KAH), and liver (KALi) transplant.

Design, setting, participants, & measurements

This retrospective cohort study used national registry data to examine IT use and survival after kidney transplantation. Separate multivariate Cox regression models were constructed to assess patient survival for IT+ and IT– KALu (n=232), KAH (n=588), and KALi (n=736) recipients.

Results

Use of IT increased during the study period. The percentage of patients considered highly sensitized (panel reactive antibody ≥20%) was not statistically significant between IT+ and IT– groups. IT+ was not associated with improvement in 1- and 10-year patient survival for KALu (P=0.20 and P=0.22, respectively) or for KAH (P=0.90 and P=0.14, respectively). However, IT+ among KALi was associated with inferior patient survival at 1 and 10 years (P=0.04 and P=0.02, respectively).

Conclusions

Use of IT for kidney transplantation among prior non-renal transplant recipients may not offer a survival advantage in KALu or KAH. However, due to limited power, these findings should be interpreted cautiously. IT+ was associated with inferior outcomes for KALi. Use of IT should be judicially reconsidered in this complex group of recipients.

Traditional Urinary Biomarkers in the Assessment of Hospital-Acquired AKI

2012-01-01

Traditional biomarkers, such as urine chemistries and urine microscopic elements, are used in the diagnosis and care of patients with AKI. Urine chemistries, such as fractional excretion of sodium and fractional excretion of urea, are useful for differentiating prerenal AKI from acute tubular necrosis only in select patients. Urine microscopy using a quantitative evaluation of the urine sediment for renal tubular epithelial cells, renal tubular epithelial cell casts, and granular casts has recently been shown to differentiate prerenal AKI from acute tubular necrosis and also provide prognostic information. Urine microscopy has also been noted to compare favorably with new urine biomarkers for diagnosis and prognosis of AKI. Thus, current information on urine diagnostics suggests that urine chemistries have a limited role in differential diagnosis of AKI, whereas urine microscopy and new urine biomarkers may be used together to differentiate prerenal AKI from acute tubular necrosis and predict such outcomes as worsened AKI, acute dialysis, and death.

AKI Associated with Macroscopic Glomerular Hematuria: Clinical and Pathophysiologic Consequences

2012-01-01

Hematuria is a common finding in various glomerular diseases. This article reviews the clinical data on glomerular hematuria and kidney injury, as well as the pathophysiology of hematuria-associated renal damage. Although glomerular hematuria has been considered a clinical manifestation of glomerular diseases without real consequences on renal function and long-term prognosis, many studies performed have shown a relationship between macroscopic glomerular hematuria and AKI and have suggested that macroscopic hematuria-associated AKI is related to adverse long-term outcomes. Thus, up to 25% of patients with macroscopic hematuria–associated AKI do not recover baseline renal function. Oral anticoagulation has been associated with glomerular macrohematuria–related kidney injury. Several pathophysiologic mechanisms may account for the tubular injury found on renal biopsy specimens. Mechanical obstruction by red blood cell casts was thought to play a role. More recent evidence points to cytotoxic effects of oxidative stress induced by hemoglobin, heme, or iron released from red blood cells. These mechanisms of injury may be shared with hemoglobinuria or myoglobinuria-induced AKI. Heme oxygenase catalyzes the conversion of heme to biliverdin and is protective in animal models of heme toxicity. CD163, the recently identified scavenger receptor for extracellular hemoglobin, promotes the activation of anti-inflammatory pathways, opening the gates for novel therapeutic approaches.

Informing Our Elders About Dialysis: Is an Age-Attuned Approach Warranted?

2012-01-01

As the fastest growing sector of the incident ESRD population, older patients constitute a group for which renal replacement therapy has special implications. Older CKD patients have unique needs by virtue of advanced age, high prevalence of comorbid conditions, slower progression of renal disease, and reduced survival. Burdens and risks attendant to dialysis may be amplified in the older patient and patients with impaired functional status or comorbid conditions, and therefore, dialysis may confer little to no survival benefit. Rates of dialysis withdrawal are highest among the oldest patients, raising the possibility that the standard content of informed consent for dialysis warrants an age-sensitive approach that is attuned to the very different balance of pros and cons of dialysis for older patients with multiple comorbidities and younger patients with limited comorbidity. Informed consent for older patients should include presentation of risks, benefits, and burdens associated with dialysis, age-specific estimates of prognosis with and without dialysis, and potential for loss of independence and decline in functional status with initiation of dialysis. In this article, medical evidence and clinical practice guidelines relevant to advance care planning for the older patient with CKD are reviewed, issues to consider in the dialogue with older patients contemplating dialysis are presented, and recommendations for an age-attuned approach to informed consent for older CKD patients are made.



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