Tenofovir-induced Fanconi syndrome and osteomalacia in two HIV-infected patients: role of intracellular tenofovir diphosphate levels and review of the literature.

We present 2 human immunodeficiency virus-infected patients with tenofovir disoproxil fumarate-induced Fanconi syndrome, leading to osteomalacia. Intracellular tenofovir diphosphate levels were measured in 1 patient and were found to be very high, with plasma tenofovir levels just slightly elevated. Fibroblast growth factor-23, a phosphaturic hormone, was decreased in both patients and is therefore unlikely to have a pathophysiological role in this pathology. The different potential factors contributing to the development of tenofovir-related kidney proximal tubular dysfunction are discussed and the data presented may help to further elucidate its pathogenesis.