Which of the following Slatements is not true?
(A) Parathyroid hormone-related protein is responsible for causing hypercalcemia in cancer patients (B) The unionized fraction of calcium in the plasma is an impoant determinant of PTH secretion (C) Mg2+ influences PTH secretion in the same direction as Ca2+ but is a less potent secretagogue (D) Ca2+influences PTH secretion by acting on a calcium sensor G-protein coupled receptor located in the parathyroid gland
(B) Ans. b. The unionized fraction of calcium in the plasma is an impoant determinant of PTH secretion"Circulating ionized calcium acts directly on the parathyroid glands in a negative feedback fashion to regulate the secretion of PTH."Magnesium is required to maintain normal parathyroid secretory responses. Impaired PTH release along with diminished target responses to PTH account fir the hypocalcaemia that occasionally occurs in magnesium deficiency