Antihypertensive effect of low calcium dialysis

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.

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.

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.

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.

These data suggest a role for low calcium dialysis in treating acute serum calcium elevation and post-dialysis hypertension in patients receiving maintenance hemodialysis.