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Kidney Week

Abstract: PO2437

Safety and Effect of Alkali Therapy on Vascular Function in Kidney Transplant Recipients: A Pilot Study

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical

Authors

  • Bohling, Rachel R., University of Colorado Denver School of Medicine, Aurora, Colorado, United States
  • Grafals, Monica, University of Colorado Denver School of Medicine, Aurora, Colorado, United States
  • You, Zhiying, University of Colorado Denver School of Medicine, Aurora, Colorado, United States
  • Kendrick, Jessica B., University of Colorado Denver School of Medicine, Aurora, Colorado, United States
Background

Acid retention is a common feature of kidney transplant recipients (KTR). Studies have found that lower bicarbonate levels in KTRs are associated with an increased risk of mortality and cardiovascular disease. We tested the hypothesis that alkali therapy was safe and feasible in KTRs and would improve vascular function.

Methods

We performed an 18-week, randomized, double-blind, placebo-controlled crossover safety and feasibility pilot study of the use of sodium bicarbonate therapy in 16 KTRs. We recruited KTRs at least one year from transplant with an eGFR ≥ 45 ml/min per 1.73m2 and a serum bicarbonate level of 16-24 mEq/L. Patients received study drug therapy (sodium bicarbonate and placebo) at 0.5 mEq/kg/lean body weight for the entire 8-week treatment period. Each treatment period was 8 weeks in duration with a 2-week washout period between treatments. All patients had to be on stable immunosuppression and antihypertensive regimen for at least one month prior to randomization. Each patient served as his or her own control. During each treatment period, patients were assessed at 4 and 8 weeks for adverse events, weight, blood pressure, gastrointestinal symptoms and pill compliance. Brachial artery flow-mediated dilation (FMD) was obtained at beginning and end of each treatment period.

Results

The mean (SD) age, eGFR, and serum bicarbonate levels were 52 (19) years, 71 (21) ml/min/1.73 m2, and 23 (2) mEq/L, respectively. Serum bicarbonate levels increased by 0.4 mEq/L during treatment. Sodium bicarbonate therapy was not associated with worsening blood pressure, weight gain, or hypokalemia. 46% of patients experienced nausea and/or bloating on sodium bicarbonate therapy compared to 40% while on placebo. The study was not powered to detect differences in FMD, but there was a trend towards improved FMD in the sodium bicarbonate group compared to the control (mean difference 1.6%; 95% confidence interval, -0.39 to 3.6; p=0.1). Additionally, a trend towards decreased 24-hour urine net acid excretion (mean (SD) change -9.0 (17.1) mEq/d, p=0.07) and ammonium excretion (mean (SD) change -6.0 (12.1) mEq/d, p=0.08) was observed.

Conclusion

Sodium bicarbonate therapy is safe and feasible in KTRs. There was a trend towards improvement in FMD, strengthening the need for a larger randomized controlled trial.