Predictors of Hypocalcemia after Thyroidectomy: Results from the Nationwide Inpatient Sample

Hypocalcemia is a common complication following thyroidectomy. However, the incidence of postoperative hypocalcemia varies widely in the literature, and factors associated with hypocalcemia after thyroid surgery are not well established. We aimed to identify incidence trends and independent risk factors of postoperative hypocalcemia using the nationwide inpatient sample (NIS) database from 1998 to 2008. Overall, 6,605 (5.5%) of 119,567 patients who underwent thyroidectomy developed hypocalcemia. Total thyroidectomy resulted in a significantly higher increased incidence (9.0%) of hypocalcemia when compared with unilateral thyroid lobectomy (1.9%; P < .001). Thyroidectomy with bilateral neck dissection, the strongest independent risk factor of postoperative hypocalcemia (odds ratio, 9.42; P < .001), resulted in an incidence of 23.4%. Patients aged 45 years to 84 years were less likely to have postoperative hypocalcemia compared with their younger and older counterparts (P < .001). Hispanic (P = .003) and Asian (P = .027) patients were more likely, and black patients were less likely (P = .003) than white patients to develop hypocalcemia. Additional factors independently associated with postoperative hypocalcemia included female gender, nonteaching hospitals, and malignant neoplasms of thyroid gland. Hypocalcemia following thyroidectomy resulted in 1.47 days of extended hospital stay (3.33 versus 1.85 days P < .001).