Metabolic acidosis in pediatric kidney transplant recipients

Background: Metabolic acidosis is a risk factor for faster kidney function decline in chronic kidney disease (CKD) and in adult kidney transplant recipients (KTRs). We hypothesized that metabolic acidosis would be highly prevalent and associated with worse allograft function in pediatric KTRs. Methods: Pediatric KTRs at Montefiore Medical Center from 2010 to 2018 were included. Metabolic acidosis was defined as serum bicarbonate < 22 mEq/L or receiving alkali therapy. Regression models were adjusted for demographic factors and donor/recipient characteristics. Results: Sixty-three patients were identified with a median age at transplant of 10.5 (interquartile range (IQR) 4.4–15.2) years and post-transplant follow-up of 3 (IQR 1–5) years. Baseline serum bicarbonate was 21.7 ± 2.4 mEq/L, serum bicarbonate < 22 mEq/L was present in 28 (44%), and 44% of all patients were receiving alkali therapy. The prevalence of acidosis ranged from 58 to 70% during the first year of follow-up. At baseline, each 1-year higher age at transplant and every 10 ml/min/1.73 m² higher eGFR were associated with 0.16 mEq/L (95% CI: 0.03–0.3) and 0.24 mEq/L (95% CI: 0.01–0.5) higher serum bicarbonate, respectively. Older age at transplant was associated with lower odds of acidosis (OR: 0.84; 95% CI: 0.72–0.97). During follow-up, metabolic acidosis was independently associated with 8.2 ml/min/1.73 m² (95% CI 4.4–12) lower eGFR compared to not having acidosis; furthermore, eGFR was significantly lower among KTRs with unresolved acidosis compared with resolved acidosis. Conclusions: Among pediatric KTRs, metabolic acidosis was highly prevalent in the first year post-transplantation and was associated with lower eGFR during follow-up. Graphical abstract: A higher resolution version of the Graphical abstract is available as Supplementary information[Figure not available: see fulltext.].