The aim of this study was to evaluate the influence of LCD on bone metabolism, and assess the indication of LCD. Fourteen patients on CAPD (m = 8, f = 6) were converted to LCD following over 1 year on standard calcium dialysate (1.75 mmol/l; SCD) treatment, and followed for 1 year. The biochemical measurements included plasma levels of Ca, P, ALP, and i-PTH. The bone mineral density (BMD) was evaluated using dual energy x-ray absorptiometry. Ca-carbonate and calcitriol were administered to maintain plasma Ca levels within the normal range. The patients were divided into three groups on the basis of the i-PTH levels just before the conversion to LCD. Group 1; n = 5, i-PTH < 65. Group 2; n = 5, 65 < or = i-PTH < 200. Group 3; n = 4, 200 < or = i-PTH (pg/ml). Mean BMD Z scores decreased significantly in group 3. Mean serum i-PTH significantly increased in all groups. These results suggest that LCD is effective for treating adynamic bone disease, which is seen in high frequency in patients undergoing peritoneal dialysis. However, these results also pointed to the disadvantage of worsening the secondary hyperparathyroidism. In conclusion, LCD should be used carefully in patients whose i-PTH levels are high, because of the possibility of bone mineral loss.