Endocrine Abstracts

Introduction: Secondary hyperparathyroidism (SHPT) is a major risk factor for the development of postoperative hypocalcaemia. Patients undergoing parathyroidectomy for SHPT receive alfacalcidol 4 mg once daily for three preoperative days as prophylaxis against postoperative hypocalcaemia.

Objectives: The aims of the study were to establish whether the current protocol for prophylaxis of hypocalcaemia was effective and secondly to assess whether the introduction of the drug cinacalcet had made any difference to the rates of postoperative hypocalcaemia in patients with SHPT.

Methods: This was a retrospective cohort study of all patients who had parathyroidectomy for SHPT from January 2003 to September 2006. The two cohorts were patients operated on before cinacalcet was licensed (pre license, 2003 and 2004) and those operated on when the drug was available (post license, 2005 and 2006).The end point was hypocalcaemia (corrected calcium <2.20 mmol/L) within 48 hours of surgery. Drug records were reviewed to ensure that patients had received prophylaxis and whether they were taking cinacalcet.

Results: 53 patients had parathyroidectomy for SHPT. 26 patients were operated on pre license, of which 10 became hypocalcaemic. Of the 27 patients operated on post license, 17 became hypocalcaemic and of these 8 were on cinacalcet. A total of 9 patients were on cinacalcet and of these 8 became hypocalcaemic within 48 hours, the remaining patient eventually became hypocalcaemic on the 5th post op day. The proportion of patients becoming hypocalcaemic since the introduction of cinacalcet increased from 38% to 63% (P=0.007).

Conclusions: Alfacalcidol 4 mg once daily for three preoperative days is an ineffective prophylactic against postoperative hypocalcaemia following parathyroidectomy for SHPT. Patients taking cinacalcet for SHPT are almost certain to become hypocalcaemic post parathyroidectomy. Since the introduction of cinacalcet the proportion of patients developing postoperative hypocalcaemia has increased significantly.