Tenofovir-induced renal tubular dysfunction presenting with hypocalcaemia

Abstract

The use of tenofovir in HIV patients has been associated with several cases of nephrotoxicity including acute tubular necrosis, Fanconi’s syndrome and nephrogenic diabetes insipidus. We present a case of tenofovir induced Fanconi syndrome presenting with symptomatic hypocalcaemia. A 50-year-old man presented with several weeks of malaise, nausea abdominal pain and muscular cramps. He had been taking didanosine, tenofovir and abacavir for the past 6 months, and had started tenofovir (along with zidovudine and didansoine) 11 months earlier as his fourth line of therapy, having started anti-retroviral therapy shortly after being diagnosed HIV-positive around 2 years earlier. He had had a similar illness 6 months earlier, thought to have been due to zidovudine toxicity, which seemed to resolve after a drug holiday and withdrawal of zidovudine. Routine biochemical screening showed a normal amylase, lactate, bicarbonate, electrolytes, glucose and renal function, however, a corrected calcium of 1.84 mmol/l and phosphate of 0.4 mmol/l, with a slightly elevated alkaline phosphatase (160 U/l). A urine dipstick was strongly positive for glucose, with traces of blood and protein. Further investigations revealed normal