<prompt> A patient is on low calcium diet for 8 weeks. Following increases to maintain serum calcium levelsPTHCalcitoninActive 24,25 dihydroxy cholecaliferolSerum phosphate level  <response>: Parathyroid hormone PTH, also called parathormone or parathyrin, is a hormone secreted by the parathyroid glands that is impoant in bone remodeling, which is an ongoing process in which bone tissue is alternately resorbed and rebuilt over time.Ref: Ganong;s review of medical physiology: 24th edition; page no: 377 