Background: Metabolic acidosis (MA) lead to several complications in more advanced stages of chronic kidney diseases (CKD) and promotes CKD progression. Acidosis is a common complication in kidney transplantation. Nevertheless few data of MA prevalence, its potential causal factors and its clinical impact on graft outcome are available. The aims of our study were to determine the prevalence of renal tubular acidosis (RTA) in our kidney recipients' population; to identify the main determinants of MA and to evaluate the impact of MA on graft outcome.

Methods: This was a monocentric retrospective study. All kidney recipients between 1996 and 2010 with a measured glomerular filtration rate (99mTc-DTPA-GFR). ) above 30 ml/min/1,73m[sup2] at one year post-transplantation were included. MA was defined as a bicarbonate level below 22 mmol/l. In order to classify the different types of RTA we used serum and urinary anion gap, urinary pH and blood potassium level. To identify the determinants of MA, we used a multivariate logistic model. To evaluate graft outcome, we used a composite criteria includinga doubling of the base-line serum creatinine concentration or graft loss. We constructed multivariate Cox models in order to assess the impact of MA on graft outcome. We split each group of MA status (bicarbonate level below or above 22 mmol/L) into two groups: GFR <60 ml/min/1,73m[sup2] and GFR between 30 and 59.9 ml/min/1,73m[sup2].

Results: 438 patients were included. 41,78 % had a MA. Among them, 57.38 % had a complete type 1 RTA, 31.15 % had an incomplete type 1 RTA, 3.28 % had a type 2 RTA and 1.09 % had a type 4 RTA. Independent risk factors for MA were recipient's age, GFR between 45-59.9 and 30-44.9 ml/min/1,73m[sup2] vs GFR above 60 ml/min/1,73m[sup2] (reference group) and maintenance immunosuppression with tacrolimus and/or mTOR inhibitor. Patients with MA and a stage 3 CKD presented an independent risk factor for worst graft outcome compared to patients without MA and stage 4 CKD (reference group) (HR: 1.89 – CI95% [1.03 – 3.46],p = 0.04). On the other hand, stage 3 CKD patients without MA did not present a risk factor for poor renal outcome compared to the reference group (HR: 1.26– CI95% [1.67 – 2.36],p = 0.48).

Conclusion: In our cohort, there was a high prevalence of MA which was mainly secondary to type 1 RTA. MA was associated with a worst graft outcome in stage 3 CKD.

CITATION INFORMATION: Garo F., Szwarc I., Mourad G., Le Quintrec M., Serre J-.E. Metabolic Acidosis after Kidney Transplantation: Prevalence, Risk Factors and Graft Outcome in a French Cohort Am J Transplant. 2017;17 (suppl 3).

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