The effects of calcium and phosphorus in hemodialysis.

Combined use of Ca supplements (orally or by dialysis) to circumvent decreased intestinal Ca absorption and aluminum compounds to reduce plasma [Pi] has been demonstrated to decrease plasma [iPTH], to normal or near normal in many patients, and to decrease the percentage of bone surface involved in bone resorption. A highly significant positive relationship between change in plasma [iPTH] and bone resorbing surface has been reported. It seems evident, therefore, that PTH must be a major factor in the bone resorption of chronic renal failure, despite the relative skeletal resistance to PTH. As a result, correction of factors that increase PTH secretion should be considered a prime goal of therapy in these patients. The osteomalacic element of renal osteodystrophy, on the other hand, is only partially controlled by these maneuvers and probably requires the additional use of vitamin D or one of its active metabolites for full correction.