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Kidney Week

Abstract: SA-PO436

FGF23, Blood Pressure, and Urinary Sodium Handling in Young CKD Patients

Session Information

  • Pediatric Nephrology - II
    October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

  • 1600 Pediatric Nephrology

Authors

  • Freundlich, Michael, University of Miami, Miami, Florida, United States
  • Cuervo, Carlos, university of miami/jackson memorial hospital, Miami, Florida, United States
  • Abitbol, Carolyn L., University of Miami/ Pediatric Nephrology, Miami, Florida, United States
Background


FGF23 has been associated with hypertension, partly attributed,to experimental observations describing FGF23-mediated enhanced Na reabsorption in the distal tubule, ↓natriuresis, volume expansion and hypertension. We examined whether FGF23 levels and urinary Na excretion are associated with blood pressure (BP) measurements in patients with incipient chronic kidney disease (CKD).

Methods


Systolic (S) and Diastolic (D) Blood pressure (BP) height- and age-adjusted percentiles (%ti), and C-terminal FGF23, 24-hour natriuresis (UNa), and fractional excetion of Na (FENa) were analyzed in young patients with CKD stages 1,2 and 3. Estimated GFR (eGFR) were calculated by cystatin (cys) and creatinine (cr) equations.

Results

57 patients (age± SD, 14.5 ±2.1 years; 41 males), 17 African Americans, 26 Whites and 14 of other ethnicities, were defined CKD stages 1,2 and 3 by eGFRcys (94±29; 37-188) and eGFRcr ( 97±33; 34-71) ml/min/1.73 m2 .Serum Na, P, 1,25(OH)2D and plasma renin were normal. UNa (162±73 mEq/24 hours), FENa (0.6±0.46; 0.03-1.8 %) or FGF23 levels (113±83; 13-606 RU/ml, normal< 200 RU/ml) did not correlate with SBP %ti (69±32; >95 in 30%) or DBP %ti (66±24; >95 in 10%). Although FGF23 levels were higher in CKD stages 2 and 3 vs Stage1, natriuresis and FENa values did not differ among groups (Table). Patients with FENa < 1st quartile (0.24%) had FGF23 levels (103 ± 55 RU/ml) comparable to those in higher quartiles (119±94 RU/ml), and SBP %ti were similar in both groups (57±32 vs 71±31, respectively).

Conclusion

Despite higher levels of FGF23 in CKD stages 2-3 vs.Stage 1, FENa values were comparable, and neither FGF23 nor FENa correlated with BP. These observations do not support a role of FGF23-mediated increased tubular reabsorption of Na as a mediator of elevated BP in the earlier stages of CKD.

GroupsNeGFRcys (ml/min/1.73m2)UNa (mEq/24 hours)FENa (%)FGF23 (RU/ml)
CKD Stage 133106±24155±810.56±0.3695±47
CKD Stage 2-32480±28°°172±610.58±0.50137±110°
All Patients5794±29165±730.57±0.46114±83

**P=0.0001;*P<0.05, both vs. CKD Stage 1

Funding

  • Clinical Revenue Support