Effects of 1,25-dihydroxyvitamin-D3 treatment on mineral balance in children with end stage renal disease undergoing chronic hemofiltration

Ten children with end stage renal disease on chronic hemofiltration (HF) were studied for a 1-yr period to evaluate the efficacy of l,25-dihydroxyvitamin-D3 (1,25(OH)2D3) therapy on biohumoral parameters of renal osteodystrophy and bone mineral content. In six of these children an acute study was done of the direct effect of the HF procedure on calcium and phosphate balance during 12 HF sessions. During the first 6 months of the study all children were treated with 1,25(OH)2D3 (0.25-0.50 µg/day) to maintain plasma calcium at 9.5-11.0 mg/dl. There was a significant increase in plasma calcium (p<0.05) and a significant decrease in plasma phosphate (p<0.01) and alkaline phosphatase concentrations (p<0.05). The circulating levels of NH2 immunoreactive parathyroid hormone did not change, remaining at the upper limits of reference values. Immunoreactive parathyroid hormone- COOH terminal fragment levels decreased significantly (p<0.05). Bone mineral content rose significantly (p<0.01). During the last 6 months of the study, to evaluate the possibility that HF alone might control secondary hyperparathyroidism, 1,25(OH)2D3 treatment was discontinued in five children; plasma calcium and phosphate were well controlled whereas hyperparathyroidism worsened in all five, and one also developed intense pruritus and hypertension. The other five children remained on 1,25(OH)2D3 treatment; two of these were transplanted, and the other three continued to show an improvement of mineral balance. The results of the acute study showed that calcium balance was positive with a mean Ca++ gain of 140 mg/HF session. The mean total phosphate removed per HF run was 574 mg. We conclude that even though a calcium gain and a high phosphate removal was obtained with our HF prescription, secondary hyperparathyroidism in children on chronic HF may be maintainued under control if 1,25(OH)2D3 supplementation is provided.