Predictive Value of Age and Serum Parathormone and Vitamin D3 Levels for Postoperative Hypocalcemia After Total Thyroidectomy for Nontoxic Multinodular Goiter

Hypothesis: Age, postoperative serum parathormone (PTH) level, and preoperative serum 25-hydroxyvitamin D(3) (25-OHD) level predict postoperative hypocalcemia after total thyroidectomy.

Design: Prospective clinical trial.

Setting: Tertiary referral center.

Patients: One hundred thirty patients with nontoxic multinodular goiter. Patients were divided into 2 groups according to the postoperative serum calcium level. Group 1 (n = 32) consisted of patients with a postoperative serum calcium level of 8 mg/dL or less, and group 2 (n = 98) consisted of patients with a postoperative serum calcium level higher than 8 mg/dL.

Interventions: The preoperative serum 25-OHD level and preoperative and postoperative serum calcium and PTH levels were determined.

Main Outcome Measures: The number of patients developing hypocalcemia and prediction of postoperative hypocalcemia by the serum 25-OHD and PTH levels.

Results: Hypocalcemia developed in 32 patients (24.6%) (group 1). The preoperative serum 25-OHD level and postoperative serum calcium and PTH levels in group 1 were significantly lower than in group 2 (P = .001). With logistic regression analysis, factors that were predictive of postoperative hypocalcemia included a preoperative serum 25-OHD level less than 15 ng/mL (P < .001; odds ratio, 558.5), a postoperative serum PTH level less than 10 pg/mL (P = .01; odds ratio, 16.4), and being older than 50 years (P = .01; odds ratio, 4.6).

Conclusions: Age, a low preoperative serum 25-OHD level, and a low postoperative serum PTH level are significantly associated with postoperative hypocalcemia. The low preoperative serum 25-OHD level was more significant than the low postoperative serum PTH level in the prediction of postoperative hypocalcemia.