Insufficiency fractures related to low-dose adefovir dipivoxil treatment for chronic hepatitis B

Area of Science:

• Nephrology and Endocrinology
• Hepatology
• Orthopedic Surgery

Background:

• Adefovir dipivoxil (ADV) is an antiviral medication used for chronic hepatitis B.
• Renal proximal tubular dysfunction is a known side effect of ADV.
• Osteomalacia is a condition characterized by softening of the bones.

Purpose of the Study:

• To report a case of multifocal insufficiency fractures secondary to adefovir dipivoxil-induced osteomalacia.
• To emphasize the association between ADV therapy, renal dysfunction, and bone fragility.
• To raise awareness among clinicians regarding this potential adverse effect.

Main Methods:

• Case presentation of a 53-year-old woman with chronic hepatitis B treated with ADV.
• Clinical evaluation including imaging (radiographs, bone scan) to identify fractures.
• Laboratory tests to assess for metabolic bone disease, including serum phosphate levels.

Main Results:

• The patient presented with recurring metatarsal insufficiency fractures and a subtrochanteric femoral fracture.
• Imaging confirmed multifocal insufficiency fractures.
• Hypophosphatemia indicated hypophosphatemic osteomalacia, attributed to ADV-induced renal proximal tubular dysfunction.

Conclusions:

• Adefovir dipivoxil can induce hypophosphatemic osteomalacia, increasing the risk of insufficiency fractures.
• Patients on long-term ADV therapy are susceptible to bone fragility, including high-risk femoral fractures.
• Early recognition and awareness are crucial to prevent delayed diagnosis and manage fractures in these patients.