Causes of Osteomalacia

The causes of osteomalacia may be grouped into vitamin disorders, calcium deficiency, phosphate deficiency, disorders of bone matrix and inhibitors of mineralization.

Vitamin disorders

1. Decreasd availability of vitamin D

• Insufficient sunlight exposure
• Nutritional deficiency of vitamin D,
• Malabsorption,
• Nephrotic syndrome

2. Abnormal response to vitamin D

• Vitamin D dependent rickets type-II,
• Gastrointestinal disorders

3. Abnormal vitamin D metabolism
4. Vitamin D dependent rickets type-I
5. X-linked hypophosphatemic rickets
6. Tumoral hypophosphatemic osteomalacia
7. Liver disease
8. Chronic renal failure
9. Diphenylhydantoin or barbiturate therapy

Calcium deficiency 

Phosphate deficiency

1.    Decreased intestinal absorption

• Nutritional deficiency of phosphorus
• Malabsorption
• Phosphate-binding antacid therapy

2.    Increased renal loss

• Vitamin D resistant rickets
• Tumoral hypophosphatemic osteomalacia
• Association with other disorders, including       paraprotenemias, glycogen stroge diseases     galactosemia, tyrosinemia, cystinosis, neurofibromatosis, Wilson’s disease, Fanconi’s syndrome.

Disorders of bone matrix

1. Hypophosphatase
2. Fibrogenesis imperfecta
3. Axial osteomalacia

Inhibitors of mineralization

1. Aluminum
2. Diphosphonates