Osteomalacia

Defective bone mineralisation causes "soft" bones due to insufficient vitamin D. The same process causes rickets in children. 

Vitamin D is created from cholesterol by the skin (UV light dependant). Diet has some vit D but not enough. 

Risks for low vitamin D

• Malabsorption disorders - IBS 
• Chronic kidney disease - kidneys add the second hydroxy group

Serum 25-hydroxyvitamin D:

• Less than 25 nmol/L – vitamin D deficiency
• 25 to 50 nmol/L – vitamin D insufficiency

Treatment

Symptomatic patients:

• 50,000 IU once weekly for 6 weeks
• 4000 IU daily for 10 weeks

Maintenance dose of 800-2000 IU per day in continued 

Check serum calcium within a month of loading regime. It may be: 

1. Low in calcium deficiency =
2. High in primary hyperparathyroidism previously masked by the vitamin D deficiency
3. High in other conditions that cause hypercalcaemia, cancer, sarcoidosis, or TB