Vitamin D

Question 1

Which organs are key for formation of active vitamin D? (hormone form)

Answer 1

Liver= hydroxylates VitD3 to form 25(OH)D3 
Kidney= site of conversion from 25(OH)D3 to 1,25(OH)2D3 i.e. calcitriol 
Parathyroid= PTH stimulates 1-alpha hydroxylase production in kidney to enable converting process in kidney

Question 2

What are the 3 main functions of vitamin D?

Answer 2

Increased intestinal absorption of Ca2+
Decreased renal phosphate and calcium absorption
Bone resorption

Question 3

What are the different causes of vitamin D deficiency?

Answer 3

Decreased synthesis

Decreased absorption in small bowel

Impaired liver hydroxylation= CLD

Impaired renal hydroxylation= CKD

End organ insensitivity

Question 4

How does vitamin D deficiency present in children?

Answer 4

Rickets

• delayed closing of fontanelles
• frontal bossing
• genu valgrum or varum

Question 5

How does vitamin D deficiency present in adults?

Answer 5

Osteomalacia

• asymptomatic
• generalised muscle and bone pain