Renal Tubular Dysfunction Associated with Tenofovir Therapy

Objective: To describe the i ncidence a nd cha racteristics of Tenofovir (TDF) induced nephrotoxicity among people living with HIV AIDS (PLHA) receiving TDF based anti-retroviral therapy (ART) at Christian Medical College, Vellore.

Method: Medical record review of all the PLHA who is being enrolled and followed up at the ART clinic at CMC, Vellore.

Results: From 2006-11, a total of 274 PLHA have been initiated on TDF based ART. 10 (3.6%) patients developed TDF induced renal dysfunction after a mean duration of 42.6 (SD 19.5) months. 5 patients were female. At the time of initiation of TDF, the mean age was 41.2 (SD 6.1) years and CD4 T-cell count was 281.2 (SD 241.3) cells/μL. 9 patients were started on an NNRTI-based regimen, while only 1 was on a Pl/r-based regimen. 5 patients were asymptomatic. Out of the 5 symptomatic patients, 3 patients complained of anorexia and tiredness only; 1 patient had bone pains and proximal pelvic girdle muscle weakness only while 1 patient had both anorexia and proximal pelvic girdle muscle weakness. Urine examination of 8 patients (all symptomatic and 4 asymptomatic patients) revealed proteinuria on urine dip stick assay (1+ to 3+) without active sediments. 9 patients had decline in the estimated creatinine clearance from mean of 84.1 (SD 21.0) to 62.1 (SD 26.3) mL/min/1.73 m2. The mean plasma phosphate level was 2.08 (SD 0.45) mg/ dL. The mean alkaline phosphatase level increased from 130.7 to 290.8 U/L. Seven patients had features of Fanconi syndrome. All symptomatic patients showed clinical improvement within 2-7 months of discontinuation ofTDF and supplementation of phosphate and calcium.

Conclusion: TDF-associated renal dysfunction has a long incubation period during which the patients are largely asymptomatic and reversible. Hence laboratory confirmation is essential with creatinine clearance, urine examination, and phosphate levels. Prompt change of TDF leads to almost complete resolution of the tubular dysfunction.