Post-Renal Transplant Metabolic Acidosis: A Neglected Entity

Metabolic acidosis is a prevalent yet overlooked entity among renal transplant recipients (RTRs) and incurs adverse effects on graft function. Although graft dysfunction and calcineurin inhibitor usage have been linked with renal tubular acidosis (RTA), there is no Indian data on prevalence or risk factors of post-transplant acidosis. A cross-sectional study was conducted on 106 adult RTRs, with a transplant duration of >6 months and an estimated glomerular filtration rate (GFR) >40 ml/min/1.73 m². Acidosis was diagnosed on basis of plasma bicarbonate and arterial pH. Serum and urine electrolytes with anion gap were determined to diagnose and type RTA. Acidosis was diagnosed in 44 of 106 patients (41.5%) with 23 (52.27%) having severe acidosis. Type I RTA was the most common subtype (52.5%) followed by type IV (30.9%) and type II RTA (7.5%). The correlation between estimated glomerular filtration rate and acidosis was minimally linear (r = 0.1088), with multivariate analysis revealing previous acute rejection episodes, current serum tacrolimus levels, cotrimoxazole usage and intake of animal proteins to be independent risk factors. The serum albumin levels were low in the acidosis group and showed linear correlation with bicarbonate levels (r = 0.298). There is a high prevalence of metabolic acidosis in RTRs with type I RTA being most common subtype. Screening of RTRs on a regular basis is a feasible approach for early diagnosis and intervention. However, prospective studies are needed to demonstrate the effect of acidosis on graft survival and benefit of bicarbonate therapy in RTRs.