Osteomalacia

Question 1

What is Osteomalacia?

Answer 1

Refers to bone softening due to defective bone mineralisation.

Rickets is the form in children before closure of growth plates.

Question 2

How is Vitamin D synthesized?

Answer 2

Vitamin D is synthesized in the skin from cholesterol with the help of UV radiation.

Question 3

What conditions may cause Vitamin D deficiency?

Answer 3

Malabsorption diseases such as:
* IBD
* CKD whereby the kidneys fail to activate Vitamin D to absorb Ca2+ and PO43-.

Question 4

What is the function of Vitamin D with respect to bone?

Answer 4

Vitamin D helps absorb Calcium and Phosphate from intestines and kidneys into blood, to facilitate bone mineralisation.

Question 5

What effect does low Ca2+ have on parathyroid?

Answer 5

Hypocalcemia will cause Type 2 hyperparathyroidism, stimulating osteoclast activity to increase serum calcium levels.

Question 6

What are the reference ranges for Vitamin D?

Answer 6

Below 25 = Vitamin D deficiency,
25-50 = Vitamin D insufficiency,
above 75 = Optimal.

Question 7

What other investigations might you order for Osteomalacia, and what may be seen?

Answer 7

Investigations may show:
* Ca2+ (low)
* PO43- (low)
* PTH (high)
* ALP (high)
* XR (osteopenia)
* DEXA (low BMD).

Question 8

How do you manage Osteomalacia?

Answer 8

Vitamin D supplementation.