Which of the following statements regarding calcium and phosphate metabolism are true?
A.	Parathyroid hormone excess produces a net increase in daily urinary calcium excretion
B.	Calcitonin is essential for the normal control of calcium metabolism in adult humans
C.	Parathyroid hormone is the single most important regulator of calcium and phosphate metabolism in humans
D.	1,25 dihydroxyvitamin D3 (calcitriol) is the active form of vitamin D in humans
Answer:A
Which of the following statements regarding calcium and phosphate metabolism are true?
A.	Parathyroid hormone excess produces a net increase in daily urinary calcium excretion B.	Calcitonin is essential for the normal control of calcium metabolism in adult humans C.	Parathyroid hormone is the single most important regulator of calcium and phosphate metabolism in humans D.	1,25 dihydroxyvitamin D3 (calcitriol) is the active form of vitamin D in humans