Osteomalacia
Osteomalacia is softening of adult bone because newly formed bone matrix is not mineralised adequately.
Key points
- Diffuse bone pain, muscle weakness and fragility fractures can occur, unlike osteoporosis, which has normally mineralised but reduced bone mass.
- Vitamin D deficiency is common, but malabsorption, kidney or liver disease, phosphate wasting and medicines can also cause it.
- Replacing vitamin D without identifying low phosphate or impaired activation may fail to correct the disorder.
The listings below do not establish the deficiency mechanism; calcium, phosphate, vitamin D and organ function should guide replacement.
Confirming defective mineralisation
Tests commonly include calcium, phosphate, alkaline phosphatase, parathyroid hormone and 25-hydroxyvitamin D. Kidney and liver function, coeliac disease and urine phosphate are assessed when results suggest a less common cause. Imaging may show insufficiency fractures.
Correcting the cause
Nutritional deficiency uses vitamin D with adequate calcium, while malabsorption may need higher or alternative formulations. Kidney-related impaired activation can require active vitamin D under specialist monitoring. Phosphate-wasting disorders need specific phosphate and hormone-directed treatment.
When to seek urgent care
Seek urgent care for inability to bear weight after minor injury, severe new hip or thigh pain, muscle spasms, seizure, confusion or an abnormal heart rhythm.