Osteomalacia: Bone Softening Causes, Symptoms & Treatment

Osteomalacia: Adult Bone Softening Disorder

Osteomalacia (ending in "-malacia" meaning softening) is the medical term for defective bone mineralization in adults, resulting in soft, weak bones. In children, the equivalent is rickets.

Primary Causes

• Vitamin D deficiency (most common)—insufficient sunlight, dietary intake, or malabsorption
• Calcium deficiency
• Phosphate deficiency
• Genetic disorders (e.g., hypophosphatasia, vitamin D-resistant rickets)
• Kidney disease—impaired vitamin D activation, phosphate wasting
• Medications: Anticonvulsants, bisphosphonates (rare), aluminum-containing antacids

Symptoms

• Bone pain (dull, aching—often lower back, pelvis, legs)
• Muscle weakness (proximal myopathy)
• Difficulty walking, waddling gait
• Bone tenderness
• Pathologic fractures (minimal trauma)
• Pseudofractures (Looser zones) on imaging

Diagnosis

• Low serum 25-hydroxyvitamin D, calcium, phosphate
• Elevated alkaline phosphatase, PTH
• Bone biopsy (rarely needed): unmineralized osteoid

Treatment

• Vitamin D supplementation (ergocalciferol or cholecalciferol)
• Calcium and phosphate replacement as needed
• Treat underlying cause (kidney disease, malabsorption, medication adjustment)
• Monitor labs and clinical response

Early diagnosis and treatment prevent irreversible deformities and fractures.