Adefovir dipivoxil is commonly used for treatment of chronic hepatitis B. The renal toxicity of adefovir dipivoxil is dose- and time-related, occurring often in patients with a daily dose over 30 mg and those with impaired renal function. We report a case of chronic hepatitis B with a history of taking adefovir dipivoxil at 10 mg/day for 4 years. The patient complained of lumbosacral and joint pain and had the diagnosis of ankylosing spondylitis (AS) or spondyloarthropathy in several hospitals before admission in our hospital. A diagnosis of acquired Fanconi syndrome and hypophosphatemia osteomalacia associated with progressive muscular weakness was made eventually. We reviewed the literature and found reports of only fewer than 10 similar cases. Clinical attention should be given to kidney damage induced by adefovir dipivoxil.
Adenine ; adverse effects ; analogs & derivatives ; therapeutic use ; Antiviral Agents ; adverse effects ; therapeutic use ; Bone Diseases, Metabolic ; chemically induced ; complications ; congenital ; Fanconi Syndrome ; chemically induced ; complications ; Hepatitis B, Chronic ; drug therapy ; Humans ; Hypophosphatemia ; chemically induced ; complications ; Male ; Muscle Weakness ; chemically induced ; complications ; Organophosphonates ; adverse effects ; therapeutic use ; Osteomalacia ; chemically induced ; complications ; Young Adult

Adefovir dipivoxil, an acyclic nucleoside analogue, has been approved for the treatment of patients with chronic hepatitis B. This agent is efficacious particularly in those who have developed lamivudine resistance. The report according to hypophosphatemia induced by low dose adefovir therapy is very rare. We report one case in which osteomalacia with hypophosphatemia developed in a patient with chronic hepatitis B on adefovir dipivoxil at a low dose, 10 mg daily. A 66-year-old man, who had been taking adefovir for more than 4 years due to lamivudine resistance, presented with muscle weakness and bone pain in both thighs. After 3 years of adefovir therapy, hypophosphatemia and elevated serum alkaline phosphatase levels had been noted. A bone scan showed multiple hot uptakes. All the image findings and clinical symptoms, such as bone pain and muscle weakness were improved after correcting the hypophosphatemia with oral phosphorous supplementation.
Adenine/adverse effects/*analogs & derivatives/therapeutic use ; Aged ; Alkaline Phosphatase/blood ; Antiviral Agents/*adverse effects/therapeutic use ; DNA, Viral/blood ; Dietary Supplements ; Hepatitis B, Chronic/*drug therapy ; Humans ; Hypophosphatemia/*chemically induced/complications ; Liver Cirrhosis/diagnosis ; Male ; Osteomalacia/*diagnosis/etiology ; Phosphates/blood ; Phosphonic Acids/*adverse effects/therapeutic use ; Whole Body Imaging

Adefovir dipivoxyl (ADV) effectively suppresses hepatitis B virus (HBV) replication but exhibits nephrotoxicity with severe hypophosphatemia when administered at a high dosage. This is the first report of severe hypophosphatemic osteomalacia induced by ADV at 10 mg/day. A 42-year-old man with HBV-related chronic liver disease presented with generalized bone pain, especially in the left ankle. He had been taking ADV for more than 1.5 years following a clinical breakthrough due to lamivudine-resistant HBV. Aggravating severe hypophosphatemia and elevated serum alkaline phosphatase levels with high bone fraction had been noted after 6 months of ADV therapy. Bone densitometry, simple bone X-rays, and a whole-body bone scan demonstrated osteoporosis and multiple areas with hot uptake, especially in the left ankle. All the image findings and symptoms improved after correcting the hypophosphatemia.
Absorptiometry, Photon ; Adenine/administration & dosage/adverse effects/*analogs & derivatives ; Adult ; Antiviral Agents/administration & dosage/*adverse effects ; Bone Density ; DNA, Viral/analysis ; Drug Resistance, Viral ; Hepatitis B virus/drug effects ; Hepatitis B, Chronic/complications/*drug therapy/virology ; Humans ; Hypophosphatemia/*chemically induced ; Lamivudine/therapeutic use ; Liver Cirrhosis/*virology ; Male ; Phosphonic Acids/administration & dosage/*adverse effects ; Tomography, X-Ray Computed