Calcium homeostasis

Vitamin D-Dependent Rickets: Actions of Parathyroid Hormone and 25-Hydroxycholecalciferol

“…The metabolically active form of vitamin D is a requirement for effective PTH action on bone to mobilize calcium [37,40]. Trummel and co-workers [45] have presented evidence that 25-HCC, once formed biologically from vitamin D in the liver, is the active metabolite effecting calcium mobilization from bone.…”

Evidence for a Direct Action of Cholecalciferol and 25-Hydroxycholecalciferol on the Renal Transport of Phosphate, Sodium, and Calcium

“…While not entirely ignored, the possibility of an additional effect of the vitamin on the transport of electrolytes by the kidney has been considered at the very least substantially unproven, and at best, controversial (1)(2)(3)(4)(5)(6). This relative dearth of experimental inquiry as regards vitamin D and the kidney is all the more remarkable in view of the numerous suggestions from the clinical literature that, in fact, the vitamin might possess a renal action (7)(8)(9)(10)(11).…”

“…The possibility has been entertained on numerous occasions that there might be important differences between the effects of physiologic as compared to pharmacologic doses of vitamin D (1,5). The discovery, isolation, and recent availability of synthetic 25HCC (23,24), an important biologically active metabolite of the parent compound, with demonstrated effectiveness on bone and gut (25,26) has allowed us -to substantially reduce the amount of material employed in studying the relationship of vitamin D to renal electrolyte transport.…”

Further studies on the interrelationship between parathyroid hormone and vitamin D.

“…Calcium homeostasis is achieved by the interplay of a number of humoral agents (1). Of central importance are the activities of parathyroid hormone (PTH) and of vitamin D. This was fully appreciated 35 years ago (2), but in spite of considerable effort, the nature of the relationship remains controversial.…”