Kidney Week

Abstract: SA-PO955

Contribution of Proximal Tubular Solute Clearance in Residual Kidney Function

Session Information

• Peritoneal Dialysis: Inflammation, Peritoneal Transport
  November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

• 703 Dialysis: Peritoneal Dialysis

Authors

• Wang, Ke, University of Washington, Seattle, Washington, United States

Ke Wang,

• Nguyen, Michelle Huyen, Kidney Research Institute, Seattle, Washington, United States

Michelle Huyen Nguyen,

• Kundzins, John R., University of Washington, Seattle, Washington, United States

John R. Kundzins,

• Goodling, Anne, Kidney Research Institute, Seattle, Washington, United States

Anne Goodling,

• Chen, Yan, University of Washington, Seattle, Washington, United States

Yan Chen,

• Zelnick, Leila R., Kidney Research Institute, Seattle, Washington, United States

Leila R. Zelnick,

• Hoofnagle, Andrew N., University of Washington, Seattle, Washington, United States

Andrew N. Hoofnagle,

• Kestenbaum, Bryan R., University of Washington, Seattle, Washington, United States

Bryan R. Kestenbaum,

Background

Residual kidney function (RKF) is associated with better health outcomes in end-stage kidney disease (ESKD). Current assessment of RKF relies on creatinine and urea clearance to estimate the glomerular filtration rate. Proximal tubular secretion is an essential intrinsic kidney function that is rarely measured in ESKD. We measured the kidney and peritoneal clearances of tubular secretory solutes in a primary cohort of incident peritoneal dialysis (PD) patients and determined association with uremic symptoms.

Methods

We enrolled 29 incident PD patients with RKF. We used liquid chromatography-mass spectrometry to quantify plasma, 24-hour urine, and dialysate concentrations of ten tubular secretory solutes. We calculated the kidney and peritoneal dialysis clearances of secretory solutes, creatinine, and urea standardized to 1.73m². We created a composite secretory clearance score as the average of each solute clearance. We assessed symptom severity using the Dialysis Symptom Index.

Results

The mean age of our cohort was 55 years, mean dialysis duration was 4 months, and mean GFR_urea+Cr was 7.8 mL/min/1.73m². The kidney clearances of secretory solutes ranged from 1.3 ml/min/1.73m² for p-cresol sulfate to 94.6 ml/min/1.73m² for hippurate (Table). The residual kidney clearance of each secretory solute was substantially higher than peritoneal dialysis clearance. Worse dialysis symptom severity was correlated with a lower composite secretory clearance score (r= -0.46; p=0.01) and, to a lesser extent, lower GFR_urea+Cr (r= -0.35; p=0.06).

Conclusion

Among incident PD patients, tubular secretory solutes are more avidly cleared by residual kidney function than peritoneal clearance. Secretory solute clearance correlates more strongly with the severity of uremic symptoms compared with GFR_urea+Cr.

Funding

• NIDDK Support