Early prediction of hypocalcemia after thyroidectomy by parathormone measurement in surgical site irrigation fluid.

Background: Improvements in surgical technique cannot eliminate the risk of hypocalcemia. We aimed to evaluate the accuracy of PTH levels in surgical site irrigation fluid (irPTH) in predicting patients at risk for postoperative hypocalcemia.

Methods: Prospective analysis of 160 consecutive patients undergoing thyroidectomy was performed. Patients were divided into 2 groups based on postoperative serum calcium levels. Patients with hypocalcemia were assigned to Group 1 (n=38), while those with normocalcemia were assigned to Group 2 (n=122). Preoperative and postoperative serum calcium levels and PTH level of surgical site irrigation fluid (irPTH), and the difference in serum calcium levels before and after thyroidectomy were determined.

Results: The difference in serum calcium levels and irPTH levels in Group 1 were significantly higher than those in group 2 (p=0.001). There was a negative correlation between postoperative serum calcium level and irPTH level (r=-0.641, p=0.0001). Patients who had irPTH level higher than 250 pg/mL had a 69-fold increased risk for postoperative hypocalcemia (OR=69.88; 95% CI: 15.37-309.94).

Conclusions: High irPTH level is significantly associated with postoperative hypocalcemia. The irPTH assay is sufficient to identify hypocalcemia in the majority of patients and it is a sensitive tool to identify patients at risk of developing postoperative hypocalcemia.