The aim of the study was an assessment of the disorders in calcium and phosphorus balance in children participating in the program of repeated haemodialyses (HD) as well as a continuous ambulatory peritoneal dialysis (CAPD). 29 patients - aged 3 to 20 (mean age 11) - were included in the study; 18 of them received HD and 11 were treated with CAPD. All patients were given alphacalcidol at the dose of 0.005 to 0.023 µg/kg/24 hours and CaCO3 at the dose of 50-200 mg/kg/24 hours. The patients from both groups (HD and CAPD) did not differ from each other with respect to their age, the time of dialysis and the dose of CaCO3. The dose of alphacalcidol was significantly higher in the group treated with CAPD. Every 4 months, patientsÕ serum was examined to determine the concentration of the following: Ca, P, parathormone (PTH int), alkaline phosphatase (AP), osteocalcin (OC) and procollagen IC (PICP). In the group of peritoneally dialysed children we found lower concentrations of phosphorus and PTH int, and higher AP activity. Low concentrations of PTH were found in 60% of patients from both groups, which in 54% of cases were accompanied by low bone metabolism markers. The number of hypercalcaemia episodes equalled 17% in HD patients and 15% in the group with CAPD. The concentrations P>3.5 mEq/l were found in 40% of tests in HD group and in 17.7% of tests in CAPD patients. Hypercalcaemia episodes did not last long and they did not cause clinical problems. Increased P concentrations resulted either from inappropriate diet or not taking CaCO3 at the time of meals. The application of alphacalcidol and CaCO3 effectively prevents the development of hyperparathyroidism in the course of chronic renal failure, although the simultaneous use of high calcium concentration may result in the development of osteopathy with decreased bone turnover. A systematic determination of the concentration of Ca, P, PTH int and a selected bone metabolism marker is necessary for the evaluation of bone metabolism in children undergoing dialysis.

Keywords: renal osteodystrophy, Calcium Carbonate, alphacalcidol, bone metabolism markers