Should female patients undergoing parathyroid-sparing total thyroidectomy receive routine prophylaxis for transient hypocalcemia?

Hypocalcemia following parathyroid-sparing total thyroidectomy is frequent and can prolong hospital stay. We undertook this study to identify preoperative predictors of postoperative hypocalcemia useful in the postoperative management of these patients. We examined patients undergoing total thyroidectomy for benign disease with preservation of at least three parathyroids from January 2000 to January 2001. Low serum calcium was considered below 8.0 mg/dL. Age, gender, preoperative serum calcium, thyroid stimulating hormone (TSH), T3, T4, albumin, cholesterol, and tryglicerides were compared in patients with normal and low serum calcium level on the second postoperative day and on discharge day by using X2 test and a model of logistic regression. Data were reported using their frequency distribution among the two groups of patients. Eighty patients, 60 females (F) and 20 males (M), underwent parathyroid-sparing total thyroidectomy. On second postoperative day, hypocalcemia occurred in 42 patients, and 56 per cent were symptomatic. Only female gender (88% F vs 12% M) (P < 0.05) and TSH <0.27 mUl/mL (38% vs 18%) (P < 0.05) predicted hypocalcemia. Similarly, female gender predicted hypocalcemia in a logistic regression analysis (P < 0.05). On the day of discharge, 22 patients had low serum calcium levels, and 50 per cent were symptomatic. At this time, only TSH value < 0.27 mlU/mL significantly predicted hypocalcemia (48% vs 17%) (P < 0.05). This was confirmed in a logistic regression analysis (P < 0.05). All but one patient (98%) eventually returned to normal serum calium levels. Despite preservation of parathyroids, transient symptomatic hypocalcemia is common after total thyroidectomy. Female gender and low TSH serum level predicted hypocalcemia. Therefore, female patients undergoing total thyroidectomy with preoperative low TSH levels should receive calcium prophylaxis to decrease morbidity, shorten hospital stay, and decrease costs.