Low-calcium dialysate and dosage of calcium carbonate.

droxide by calcium carbonate. The calcium carbonate dosage ranged from 3 to 6 g/day. They found that low-calcium dialysate induces a negative calcium balance during hemodialysis (HD) with a worsening of SHPTH and concluded that a change in the current policy of the treatment of renal osteodistrophy can be necessary to prevent these alterations. For 1 yr, we studied the effect oflow-calcium dialysate on the severity of SHPTH In 26 HD patients without vitamin D therapy in the previous 2 yr. The dialysate calcium concentration was lowered from 1 .62 to 1.25 nunol/L. Gradually, we increased the dose of calcium carbonate and decreased the dose of aluminum hydroxide. One year after the dialysate calcium was lowered, the oral dose ofcalcium carbonate rose from 3.2 ± 2.6 to 9.2 ± 5.6 g/day (P < 0.001), with stable levels of serum calcium (8.8 ± 1 . 1 versus 9. 1 ± 1 .4). In 22 patients (85%). alumInum hydroxide was stopped, and in the remaining 4 patients, the dose was lowered. These vanations did not produce an increase in the incidence of hypercalcemla or hyperphosphoremla. In the total group. we did not find a significant variation in the levels of intact parathyroid hormone (IPTH) (324 ± 1 15 versus 3 1 1 ± 256 pg/mL) or alkaline phosphatase (230 ± 115 versus 224 ± 127). We analyzed the evolution ofiPTH in each case. In 15 patients (58%). the iPTH decreased; in 6 subjects (23%), it remained stable. and in only 5 (19%), it increased. However, one of these five patients had a basal iPTH that was Inappropriately low (57 pg/mL) and it Increased to an adequate level (187 pg/mI); two of the remaining four subjects did not take the recommended calcium dosage. The tolerance to low-calcium dialysate was good. There were no modifications in the predlalysis, postdlalysis, or interdialysis blood pressure. Furthermore, the prevalence of hypotensive episodes or cramps during the dialysis sessions did not change. In conclusion, the reduction of dialysate calcium concentration allowed the administration of high doses of calcium carbonate and the suppression of aluminum hydroxide in most of patients, with adequate phosphorus control. Large doses of calcium supplements are necessary and safe to control PTH secretion in HD patients with low-calcium dialysate, without the need of using vitamin D active metabolites in most cases. The administration of high doses of calcium carbonate in these patients could prevent the net calcium boss and avoid the repetitive stimulation of PTH secretion during HD. Juan F. Navarro Manuel Mac#{237}a Javier Garcia Department of Nephrology Hospital Ntra. Sra. de Candelaria S/C de Tener J’e Canary Islands, Spain REFERENCES