VITAMIN D

VITAMIN D
Vitamin D is a fat-soluble vitamin whose synthesis begins in the skin.
In vitamin D deficiency, calcium and phosphorus metabolism is deranged, and patients develop osteomalacia and muscle weakness
The main causes for acquired vitamin D deficiency include inadequate diet, malabsorption, and decreased exposure to solar ultraviolet B (UVB) radiation.
Elderly and debilitated patients are particularly predisposed
Although rigorous use of sunscreens can lead to vitamin D deficiency,
The symptoms of vitamin D deficiency also may develop due to inborn errors of metabolism.
In vitamin D–dependent rickets type I, renal vitamin D-1a -hydroxylase is decreased.
In vitamin D–dependent rickets type II, mutations in the nuclear vitamin D receptor cause resistance to physiologic levels of 1,25-dihydroxyvitamin D.
This causes not only musculoskeletal and endocrinologic disturbances but also loss of hair.
Massive doses of vitamin D and calcium treat all the findings except the hair loss