Predictors of hypocalcemia occurring after a total/near total thyroidectomy

The aim of this study was to identify the predictors of early postoperative hypocalcemia after a total/near total thyroidectomy in order to select patients for prompt treatment to prevent symptomatic hypocalcemia.

Patients with hypocalcemia within 24 h of surgery were identified as Group I and normocalcemic patients as Group II. The perioperative serum total calcium (tCa, ionized calcium (iCa) and intact parathormone (iPTH) were measured perioperatively. Skin closure (SC) was accepted as the reference time point. Data are expressed as the mean +/- SEM.

The study included 73 patients. Hypocalcemia (Group I) was detected in 40 patients (54%) within the first 24 h postoperatively. Symptomatic hypocalcemia was detected in 40% of the patients in Group I. Intact parathormone values at 10 min of SC were significantly lower in Group I (P = 0.001). IPTH measurement at 10 min of SC showing a >/=30% decrease had a 92.3% sensitivity and 92.6% specificity in predicting hypocalcemia after a total/near total thyroidectomy. The postoperative day 15 mean tCa, iCa, and iPTH values were similar in both groups of patients. The mean iPTH level was 16.79 +/- 2.5 pg/dl at 10 min after SC in patients who developed symptomatic hypocalcemia.

Intact parathormone measurement 10 min after SC is helpful to predict early postoperative hypocalcemia. An IPTH decrease >/=30% at this time point estimates the risk of postoperative hypocalcemia.