CALCIUM ACETATE VERSUS CALCIUM-CARBONATE AS ORAL PHOSPHATE BINDER IN PEDIATRIC AND ADOLESCENT HEMODIALYSIS-PATIENTS

Calcium carbonate is widely used as an oral phosphorus binder to contr ol hyperphosphatemia in children on maintenance hemodialysis. Intestin al calcium absorption may induce hypercalcemia, particularly if calcit riol is given simultaneously. In adults, calcium acetate binds phospho rus more effectively than calcium carbonate, while reducing the freque ncy of hypercalcemic events. We therefore compared calcium acetate wit h calcium carbonate in nine pediatric patients on long-term maintenanc e hemodialysis. Following a 1-week withdrawal of phosphorus binders, c alcium carbonate was administered for 7 weeks; after a second withdraw al, calcium acetate was given for another 7 weeks. All patients receiv ed calcitriol regularly. Both agents lowered the serum phosphorus conc entration significantly (calcium carbonate 5.7 +/- 1.4 vs. 7.7 +/- 2.1 mg/dl, P<0.005; calcium acetate 5.8 +/- 1.4 vs. 7.8 +/- 2.0 mg/dl, P< 0.005). Significantly less elementary calcium was ingested with calciu m acetate than with calcium carbonate: 750 (375-1,500) vs. 1,200 (0-3, 000) mg calcium/day, P<0.0001. With calcium carbonate serum calcium in creased significantly. The number of episodes of hyperphosphatemia or hypercalcemia did not differ between treatments. Intact plasma parathy roid hormone (PTH) decreased significantly with both phosphate binders , and serum 25-hydroxyvitamin D-3 increased. There was a close relatio nship between serum phosphorus and PTH in prepubertal but not in puber tal patients. We conclude that hyperphosphatemia can be controlled eff ectively by both calcium acetate and calcium carbonate in pediatric he modialysis patients. The oral load of elementary calcium is reduced si gnificantly by binding phosphorus with calcium acetate instead of calc ium carbonate; nevertheless, hypercalcemic episodes remain equally fre quent with both phosphate binders.