Preventing postoperative hypocalcemia in patients with Graves disease: a prospective study.

Background: Hypocalcemia occurs after total thyroidectomy (TT) for Graves disease via parathyroid injury and/or from increased bone turnover. Current management is to supplement calcium after surgery. This study evaluates the impact of preoperative calcium supplementation on hypocalcemia after Graves TT.

Methods: A prospective study of patients with Graves disease undergoing TT was performed. Patients with Graves disease managed over a 9-month period took 1 g of calcium carbonate (CC) three times a day for 2 weeks before TT. Those managed the previous year without supplementation served as historic controls. Age-, gender-, and thyroid weight-matched, non-Graves TT patients were procedure controls. Patient demographics, postoperative laboratory values, complaints, and medications were reviewed. Parathyroid hormone (PTH)-based postoperative protocols dictated postoperative CC and calcitriol use.

Results: Forty-five patients with Graves disease were treated with CC before TT, and 38 patients with Graves disease were not. Forty control subjects without Graves disease were identified. Age, gender, and thyroid weight were comparable. Preoperative calcium and PTH levels were equivalent. PTH values immediately after surgery, at postoperative day 1, and at 2-week follow-up were equivalent. Postoperative use of scheduled CC (p = 0.10) and calcitriol (p = 0.60) was similar. Postoperatively, patients with untreated Graves disease had lower serum calcium levels than pretreated patients with Graves disease or control subjects without Graves disease (8.3 mg/dL vs. 8.6 vs. 8.6, p = 0.05). Complaints of numbness and tingling were more common in nontreated Graves disease (26%) than in pretreated Graves disease (9%) or in control subjects without Graves disease (10%, p < 0.05).

Conclusions: Calcium supplementation before TT for Graves disease significantly reduced biochemical and symptomatic postoperative hypocalcemia. Preoperative calcium supplementation is a simple treatment that can reduce symptoms of hypocalcemia after Graves TT.