Vitamin D - Week 13 PBL Flashcards
1
Q
What are types of sources for Vitamin D?
A
Sunlight
Diet
Supplements
2
Q
What is the pathway to form active Vitamin D?
A
Diet: cholecalciferol —> 25-hydroxy-D3 in liver —> 1,25-dihydroxy-D3 in kidney = active metabolite
UV: 7dehydrocholesterol —> pro-D3 —> cholecalciferol
3
Q
What other Vit D metabolite does the kidney form?
A
24,25(OH)2D3 if Vit D supply is adequate
4
Q
What is the role of 1,25 dydroxyvitamin D?
A
Stimulates instestinal Ca and Phosphate absorption
Stimulates bone resorption
Needed for proper bone mineralisation
5
Q
How is 1,25 dihydroxy Vit D regulated?
A
By parathyroid hormone
By phosphate
And neg feedback loop of 1,25 Vit D
6
Q
How does low Vit D lead to weaker bones?
A
Low Vit D = low Ca = bone resorption to maintain serum. Ca = less bone building = weaker bones
