Tenofovir disoproxil fumarate (TDF) is one of the first-line treatment options in
chronic hepatitis B (CHB). Despite its efficacy in suppressing viral load and a high resistance barrier, long life maintenance
therapy is required. Registration studies demonstrated TDF to be a safe
drug. However, post-marketing experience reported cases of serious nephrotoxicity associated with
hypophosphatemia,
osteomalacia and, even more recently,
Fanconi syndrome associated with TDF
therapy in CHB monoinfected patients.Here the authors report a case of a 40 year-old male, with a CHB monoinfection, that, three years after TDF
therapy, developed a progressive
chronic kidney disease with a serious
hypophosphatemia and a secondary
osteomalacia that was manifested by bone
pain and multiple
bone fractures. Further investigational analyses unveiled a
proximal renal tubular dysfunction, which fulfilled most of the diagnostic criteria for a
Fanconi syndrome. After TDF withdrawal and oral supplementation with
phosphate and
calcitriol, his renal function stabilized (despite not returning to normal),
proximal renal tubular dysfunction abnormalities resolved as well as
osteomalacia. In conclusion, physicians should be aware that, in CHB monoinfected patients under TDF
therapy, serious renal damage is possible and preventable by timely monitoring serum
creatinine and
phosphate.