| Popis: |
The existence of a low-bone turnover, non-aluminium related, has been more prevalent in recent years. Factors involved include the increasing number of older and diabetic patients initiating dialysis. Also higher intake of calcium salts and the widespread use of vitamin D derivates may play a role. Demonstration of low PTH secretion allows the recognition of the group of patients with special risk of adynamic bone disease. Little can be done to improve bone remodelling apart from correct management of risk factors previously mentioned. A decrease in dialysate calcium concentration can act in this way, but the long term effect of this procedure on bone mineral density has scarcely been established. The aim of this study was to evaluate the long term effect of lowering the dialysate calcium concentration from 3.5 to 3 mEq/L on bone mass and PTH activity in patients with hypoparathyroidism. We studied 19 patients with PTH120 pg/ml and calcemia between 8.5 and 10.5 mg/dl, without aluminium intoxication. Blood levels of Ca, P, alkaline phosphatase, aluminium, iPTH and dialysis doses were measured every 4 months during the two years of follow-up. Phosphate binders were closely monitored. Also calcium dietary feeding was measured by a 5-day dietetic registry at the beginning and 6 and 12 months later. Bone mineral density was assessed by quantitative computed tomography of the distal radius initially and after 18 months. PTH values had significantly increased from the first measurement (from 46 +/- 33 to 97 +/- 68 four months later). At the end of follow up, 8 patients (42%) had reached the objective of maintaining a PTHi above 120 pg/ml, while 11 had not reached it (3 were previously parathyroidectomized and two were diabetic). Only one patient has developed an exaggerated PTH response that has been controlled with oral vitamin D. No bone mineral loss was observed during the follow up. In conclusion, the use of a 3 mEq/l dialysate calcium may improve hypoparathyroidism in a substantial number of patients, avoiding the untoward effect that lower calcium concentration has on bone mineralization. |
