Tenofovir-induced Osteomalacia

We present an HIV-infected woman in whom antiretroviral treatment with tenofovir disoproxil fumarate (TDF) induced severe skeletal pain, synovial effusions and multiple fractures secondary to a Fanconi syndrome with hypophosphatemia and osteomalacia. TDF interferes with the replication of mitochondrial DNA in the proximal tubules of the kidney, which can explain the delayed onset of this form of renal phosphate loss. Nephrotoxicity had been precipitated by cotreatment with lopinavir/r, an HIV protease inhibitor which increases tenofovir serum levels and inhibits the tubular multidrug resistance protein 4, which is responsible for the efflux of tenofovir from tubular cells.Awareness is needed to link the typically prolonged onset of clinical symptoms with TDF exposure and then establish the correct diagnosis.