Question

2. Baroncelli and coworkers (JCEM 93:1743-1750 [2008]) report that the incidence of rickets (prepubertal Vitamin D deficiency) among Egyptian children is in excess of 13%. Which of the following statements correctly describe physiologic consequences of vitamin D deficiency during childhood? (there may be more than 1 correct answer)

A. 1α-hydroxylase activity in renal tissue will be increased in children with Vitamin D deficiency.

B. Serum concentrations of calcium will be increased in children with Vitamin D deficiency.

C. Synthesis of calbindin in intestinal epithelium will be increased in children with Vitamin D deficiency.

D. Osteoblast-dependent mineralization of the collagen matrix of bone will be increased in children with Vitamin D deficiency.

E. Secretion of calcitonin from the C cells of the thyroid will be increased in children with Vitamin D deficiency.

Answer 1

The physiologic consequences of vitamin D deficiency during childhood are as follows:

E. Secretion of calcitonin from the C cells of the thyroid will be increased in children with Vitamin D deficiency.

( If there is an overshoot in serum calcium levels, the parafollicular cells of the thyroid gland that is known as C cells which secrete calcitonin to block bone calcium resorption, helping to keep serum calcium levels in the normal range, As the calcium resorption is inhibited then there will be inhibition of transfer of calcium from bone tissue to blood which will decrease the serum concentration of blood ).