Hepatitis B Hypophosphatemic Osteomalacia after Low-Dose Adefovir Dipivoxil Therapy for

40-yr-old male presented with a 5-month history ofbonepaininvolvingbothknees,ankles,andseveralribs with no antecedent trauma. He had an antalgic gait,tenderness involving the bony margins of both knees,but no synovitis. He had a history of chronic hepatitisB infection, receiving lamivudine at a daily dose of 100mgfor43monthsandadefovirdipivoxil(adefovir)atadailydoseof10mgforthepast29months.Hehadbeenreceiving tramadol hydrochloride intermittently forpain relief.Investigations revealed a reduced serum phosphatelevel of 2.0 mg/dl (0.64 mmol/liter), normal serum cor-rected calcium of 8.8 mg/dl (2.20 mmol/liter), PTH of39 pg/ml (4.1 pmol/liter), 25-hydroxyvitamin D