SP726RELATIONSHIP OF SERUM BICARBONATE LEVELS WITH 1-YEAR GRAFT FUNCTION IN KIDNEY TRANSPLANT RECIPIENTS

Abstract

INTRODUCTIONANDAIMS: Metabolic acidosis (MA) is a typical complication of CKD(chronic kidney disease) and an independent risk factor for kidney disease progression. Interestingly,MAis also highly prevalent in kidney transplant recipients (KTRs) ranging from12% to 58%. Recently, a study fromKorea has shown thatMAafter kidney transplantation was also associated with increased risk of graft loss and death.However, this was the first study that has been published suggesting an impact ofMAon graft function. Thus, we wanted to test if there is a relationship between serumbicarbonate levels and graft function in the first year after kidney transplantation in KTRs. METHODS: We performed a post‐hoc analysis of a single‐center open‐label randomized study testing denosumab for its effects on bone mineral density in 90 KTRs. MA was defined as serum bicarbonate <22 mmol/l. Graft function was determined by eGFR according to CKD‐EPI equation. Values were set to missing if patients were treated with alkali therapy 1 month before measurement. RESULTS: MA was highly prevalent at baseline (63%) and decreased to 39% after 3 months and to 28% after 1 year. Accordingly bicarbonate levels and in parallel eGFR values increased during the first year. Mean bicarbonate level at baseline was 20.6±3.0 mmol/l, 22.062.8 mmol/l after 3 months and 22.762.7 mmol/l after 1 year. Mean eGFR at baseline was 53.3±15.8 ml/min/1.73m2, 55.1±15.8 ml/min/1.73m2 after 3 months and 56.9±18.5 ml/min/1.73m2 after 1 year. Mean changes of eGFR after 1 year in KTRs with and without MA are shown in table 1. Increasing values for serum bicarbonate resulted in significantly (p=0.018) higher eGFR using a linear mixed model with random intercept, where the previous randomization showed no significant effect. CONCLUSIONS: Prevalence of metabolic acidosis was highest at baseline and decreased within the first year after transplantation. In parallel, eGFR values increased from baseline to 1 year. Bicarbonate levels were positively correlated with eGFR during the first year after kidney transplantation. Interestingly, mean increase in eGFR after the first year was higher in KTR without MA compared to recipients with MA suggesting a potential role of MA on kidney graft function. Our data confirm previously published data indicating metabolic acidosis as an independent risk factor for graft outcome after kidney transplantation (Table presented).