Antihypertensive effect of low calcium dialysis

Background: During maintenance hemodialysis acute elevation in serum calcium is common. Low calcium dialysis is advocated as a therapy for prevention of dialysis-induced hypercalcemia. Approximately 16% of our chronic hemodialysis patients experience elevated arterial blood pressure during the hemodialysis session, becoming hypertensive by the end of the treatment. All these patients exhibited post-dialysis hypercalcemia. Objectives: To investigate the effect of low calcium dialysis on post-dialysis hypertension in view of an evident link between serum calcium and blood pressure in both normal renal function and chronic renal failure patients. Methods: We evaluated 19 chronic hemodialysis patients in whom both post-dialysis hypertension and PDHCa were observed. We investigated changes in serum total calcium, ionized calcium, intact parathormone levels and arterial blood pressure in response to 4 weeks low calcium dialysis as a treatment for PDHCa. Results: When PDHT patients were treated with low calcium dialysis, post-dialysis blood pressure was significantly decreased compared to pre-dialysis values (155.3 ± 9.7/82.2 ± 7.9 mmHg pre-dialysis vs. 134.1 ± 20.8/80 ± 8.6 mmHg post-dialysis, P = 0.001). Additionally, post-dialysis blood pressure was significantly lower than post-dialysis blood pressure prior to the low calcium dialysis treatment (176.1 ± 15/86 ± 10.8 mmHg post-standard dialysis, 134.1 ± 20,8/80 ± 8.6 mmHg after low calcium dialysis, P = 0.001). A decline in post-dialysis serum calcium (2.34 ± 0.2 vs. 2.86 ± 0.12 mmol/L, P = 0.04) and ionized calcium (1.17 ± 0.12 vs. 1.3 ± 0.06 mmol/L, P = 0.03) compared to pre-dialysis levels was also achieved by this treatment, with no significant changes in iPTH levels. Conclusions: These data suggest a role for low calcium dialysis in treating acute serum calcium elevation and post-dialysis hypertension in patients receiving maintenance hemodialysis.