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Abstract: FR-PO204

Association of Serum Bicarbonate Levels with Kidney Function Decline in Patients with Polycystic Kidney Disease

Session Information

Category: CKD (Non-Dialysis)

  • 1901 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

  • Yapa, Roshini, University of Colorado, Denver, Colorado, United States
  • You, Zhiying, UC Denver, Aurora, Colorado, United States
  • Gitomer, Berenice Y., Div. Renal Diseases and Hypertension,, Aurora, Colorado, United States
  • Chonchol, Michel, University of Colorado, Denver, Colorado, United States
  • Kendrick, Jessica B., University of Colorado School of Medicine, Aurora, Colorado, United States
Background

Lower serum bicarbonate levels are associated with kidney disease progression in patients with chronic kidney disease. Whether serum bicarbonate levels are associated with kidney disease progression in patients with polycystic kidney disease (PKD) is unknown. We tested the hypothesis that lower bicarbonate levels are associated with kidney function decline in patients with PKD.

Methods

We included 774 patients from the HALT-PKD Study A (N=395) and B (N=379) with baseline serum bicarbonate levels and at least three measurements of estimated glomerular filtration rate (eGFR). Bicarbonate was examined as a continuous variable and in categories (≤ 24, 25-28 and >28 mEq/L, with 25-28 mEq/L as the reference group). The outcome was yearly change in slope of eGFR. Linear regression models were used to examine the association between serum bicarbonate and change in eGFR.

Results

The mean (SD) age was 43 ± 10 years. The mean (SD) serum bicarbonate and eGFR at baseline was 26.7 ± 2.4 mEq/L and 70 ± 26 ml/min/1.73m2, respectively. Participants with serum bicarbonate ≤ 24 mEq/L had lower eGFR, higher body mass index (BMI) and systolic blood pressure (SBP) than those with bicarbonate levels >24 mEq/L. In the fully adjusted model, each 1 mEq/L increase in serum bicarbonate level was associated with a 0.1 ml/min/1.73m2 increase in annual slope of eGFR (β 0.1 ml/min/1.73m2, 95% CI 0.002 to 0.15, p=0.04). A serum bicarbonate level ≤ 24 mEq/L was associated with a yearly decline in eGFR slope in unadjusted analysis and in partially adjusted analysis, but only trended towards significance in the fully adjusted model (p=0.09).

Conclusion

Lower serum bicarbonate levels are associated with an increased risk of decline in eGFR in patients with PKD.

β Estimate (95% CI)
Serum Bicarbonate mEq/LUnadjustedModel 1Model 2
Per 1 mEq/L increase0.1 (0.05 to 0.2)0.1 (0.02 to 0.18)0.1 (0.002 to 0.15)
≦ 24
25-28
> 28
-0.7 (-1.22 to -0.16)
REF
0.3 (-0.15 to 0.78)
-0.5 (-1.06 to -0.04)
REF
0.2 (-0.20 to 0.69)
-0.4 (-0.93 to 0.07)
REF
0.2 (-0.26 to 0.64)

Model 1: adjusted for age, gender, race, treatment randomization Model 2: adjusted for model 1 plus smoking, cardiac history, BMI, SBP, baseline eGFR and urine albumin to creatinine ratio

Funding

  • Other NIH Support