[Changes in calcium metabolism after kidney transplantation].

Prospective study was performed to measure the changes in calcium metabolism after kidney transplantation. 139 recipients received calcium substitution (1st group) and 81 patients were treated with alfacalcidol (2nd group). Serum Ca, P, Mg, alkaline phosphatase (AP) and intact PTH levels were determined before transplantation and at 1, 3, 6, 12 and 24 months thereafter in the two groups. Femoral and vertebral bone mineral density was measured with bone densitometer at the same period. The serum Ca level elevated and the serum P concentration decreased significantly in both group. The mean serum Mg and AP concentration changed in the normal range after the transplantation. The intact PTH level decreased significantly in both group at 2 years following transplantation. The intact PTH concentration changed from 17.1 pmol/l to 9.3 pmol/l in the 1st group, and it is decreased from 17.7 pmol/l to 7.9 pmol/l in the 2nd group. Bone densitometry showed osteoporosis in both group. At 12 months and at 24 months after kidney transplantation bone mineral density (BMD) of lumbar spine was 90.8% and 86.9% in the 1st group and 85.3% and 81% in the 2nd group. At the same time BMD of the femoral region was 84.4% and 85.5% in the 1st group and 82.0% and 81.3% in the 2nd group. The BMD did not changed significantly in the 1st compared to the 2nd group. During this period osteonecrosis was diagnosed in 6 patients in the 1st group and in 9 cases in the 2nd group. In conclusion, the serum Ca and P levels were in the normal range after kidney transplantation. The alfacalcidol treatment significantly decreased the intact PTH concentration compared to the calcium substitution. Moderate osteopenia was observed in both groups after the transplantation, despite of the administration of alfacalcidol treatment.