Incidence of and risk factors for tenofovir-induced nephrotoxicity: a retrospective cohort study


Tony Antoniou, PharmD, 410 Sherbourne Street, 4th Floor, Toronto, Ontario, Canada M4X 1K2. Tel: 416 867 7460, ext. 8344; fax: 416 867 3726; e-mail:



Despite the recent publication of case reports describing various manifestations of tenofovir-related nephrotoxicity, data regarding the incidence of and risk factors for this adverse effect are currently lacking.


A retrospective cohort study of patients from four centres in Toronto, Canada, enrolled in the tenofovir expanded access programme with a minimum of 3 months follow up, was carried out.


A total of 172 patients receiving tenofovir disoproxil fumarate (TDF) for a median of 16 months (range 3–25 months) were included in the study. Seven (4%) patients developed grade 1 (>44 μmol/L from baseline) increases in serum creatinine (SCr) during follow up; no patient developed grade 2 or higher nephrotoxicity. Fifteen (8.7%) patients had an increase in SCr of greater than 1.5 times baseline values during follow up. Four (2.3%) patients discontinued TDF because of an increase in SCr and/or abnormal urinalysis. Of 62 patients with a urinalysis, grade 1 or higher proteinuria (< 3 g/L) was observed in 27 (43%) patients. Only baseline SCr [odds ratio (OR)=0.51 per 10 μmol/L increase; P=0.0005] and baseline creatinine clearance (1.26 per 10 mL/min increase; P=0.01) were significantly associated with ever having a 1.5-fold increase in serum creatinine. Twenty-eight (16%) and 11 (6%) patients developed grade 1 (serum phosphorus≤0.71 mmol/L) and grade 2 (serum phosphorus≤0.61 mmol/L) hypophosphataemia during follow-up, respectively.


Although slight increases in SCr did occur after starting TDF, clinically significant nephrotoxicity was rare. The clinical significance of TDF-related hypophosphataemia and proteinuria requires further study.