Predictable criteria for selective, rather than routine, calcium supplementation following thyroidectomy

Objectives: To identify patients at risk for symptomatic hypocalcemia and to make recommendations for safe, selective calcium supplementation. Design: Retrospective review of consecutive patients undergoing thyroidectomy. Patients were divided into 2 groups. Group 1 (the "high-risk/calcium-yes" group) included patients who were found to have (1) postoperative symptoms of hypocalcemia (ie, tingling and numbness), (2) any postoperative serum calcium level of less than 7 mg/dL, or (3) a parathyroid hormone level of less than 3 pg/mL on postoperative day 1. Group 2 (the "lowrisk/calcium-no" group) included all other patients. Demographic, operative, biochemical, and pathologic data, as well as postoperative calcium supplementation data, were recorded. Trends in serum calcium level and parathyroid hormone level were analyzed during the immediate postoperative period to identify specific factors unique to group 1. Patients: A total of 156 patients who underwent a thyroidectomy. Setting: Tertiary care center. Results: Of the 156 patients reviewed, 78% were female, 70% had a malignant disease, and the median age at operation was 50 years. Thirty-four patients (22%) were in group 1, and 122 patients (78%) were in group 2. Twenty-nine (19%) patients had a parathyroid hormone level of less than 3 pg/mL within 24 hours after a thyroidectomy. Patients who underwent a central neck dissection (P=.001), had malignant disease (P=.01), or had a documented removal of the parathyroid gland (with or without autotransplantation) at operation (P=.013) were most likely to be classified into group 1. Forty-two percent of patients in group 2 had either a parathyroid hormone level of less than 6 pg/mL or a serum calcium level of less than 8 mg/dL on postoperative day 1, but all patients in group 1 who were symptomatic met these parameters. Conclusion: Limiting supplementation to patients with a parathyroid hormone level of less than 6 pg/mL or a serum calcium level of less than 8 mg/dL on postoperative day 1 may eliminate unnecessary calcium/vitamin D intake, phlebotomy, and follow-up assessments in up to 58% of patients undergoing thyroidectomy. Validation is required in a prospective setting.