Prevalence and risk factors of renal tubular acidosis after kidney transplantation

Objective: To asses the prevalence of post-transplant renal tubular acidosis (RTA) and its associatedrisk factors.Methods: A cross-sectional study was conducted on 100 live related renal transplant recipients, with a transplant duration of more than one year and an estimated GFR 40 ml/min/1.73m². Patients with acute graft rejection within last 6 months, unstable graft function, acute urinary tract infection and diarrhoea were excluded. Renal Tubular Acidosis (RTA) was diagnosed on the basis of plasma bicarbonate, venous pH, urine and serum anion gap measurements.Results: Out of 100 patients (74 male, 26 female) RTA was observed in 40 (29 male, 11 female). Patients with RTA had a lower GFR (65.87±12.35 versus 74.23±14.8 ml/min/1.73m², P= 0.004) and higher number of previous acute rejections. Lower bicarbonate was associated with higher serum chloride (108.2±3.19 versus 105.72±3.9 mEq/L, P= 0.001) and higher potassium concentration (3.95±0.53 vs 3.61±0.46 mg/dl, P= 0.001). Higher phosphorous level (3.46±0.71 in RTA vs 3.19±0.59 mg/dl in non-RTA, P= 0.045) but lower total serum calcium concentrations were found in patients with RTA. Intake of angiotensin converting enzyme inhibitors (ACE I) was associated with the development of RTA. Calcineurin inhibitor (CNI) therapy was not associated with an increased likelihood of RTA. While no difference was noted in sex, age, pre-transplant dialysis duration, post transplant period, body mass index and serum albumin levels.Conclusion: There is a high prevalence of RTA in renal transplant recipients. In most of the patients, this is subclinical and does not require treatment.