Effect of Sodium Bicarbonate on Indicators of Volume Retention in Metabolic Acidosis After Kidney Transplantation: A Post-Hoc Analysis

Rationale & Objective: Metabolic acidosis is a frequent complication after kidney transplantation, commonly treated with sodium bicarbonate. However, concomitant sodium loading raises concerns about potential volume retention. This study aims to assess its impact on clinical and biochemical markers of volume retention, as its effects post-transplant remain insufficiently studied. Study Design: Post-hoc analysis of a randomized, single-blinded, placebo-controlled multicenter trial (Preserve-Transplant Study). Setting & Participants: Total of 240 kidney transplant recipients with metabolic acidosis were randomized 1:1 across 3 University hospitals in Switzerland. Intervention: 1.5-4.5 g/day sodium bicarbonate or placebo for 24 months. Outcomes: Primary outcomes included body weight, N-terminal prohormone of brain natriuretic peptide, plasma renin, plasma aldosterone, aldosterone-to-renin ratio (the latter 4 log-transformed), nocturnal systolic blood pressure dipping, and antihypertensive agent use. Secondary outcomes included the occurrence of hypertension, hospitalization due to uncontrolled hypertension or volume overload, and sodium and potassium balance over time. Analytical Approach: Descriptive statistics and mixed-effects regression models. Results: ≤ 0.001) in the sodium bicarbonate group were identified. There was no or weak evidence for treatment effects on other secondary outcomes. Subgroup analyses showed no major differential effects. Limitations: Post-hoc analysis, mainly Caucasian study population. Conclusions: Our findings did not provide clear evidence for unfavorable effects of sodium bicarbonate on volume retention. Further research is required to clarify risks. Trial Registration: ClinicalTrials.gov (ID: NCT03102996).