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Am Fam Physician. 2007;75(6):910-912

Background: Up to one third of patients develop hypocalcemia following thyroidectomy. Although 97 percent of cases are self-limiting, hypocalcemia causes significant and distressing symptoms and increases in medical costs. Monitoring declines in serum calcium or intact parathyroid hormone (iPTH) levels has been suggested to predict which patients are at risk of hypocalcemia, but this may not be feasible if the patient is discharged too early. Roh and Park studied the effect of providing routine oral calcium and vitamin D supplements to patients following thyroidectomy.

The Study: The study enrolled 90 patients who were scheduled for total thyroidectomy. Participants had normal renal function and no prior neck surgery. In all patients, the parathyroid glands were carefully preserved. After surgery, patients were randomly assigned to receive or not receive calcium (3 g per day) plus vitamin D (1 g per day) for 14 days. Serum ionized and total calcium and iPTH levels were monitored before surgery, one hour after surgery, and after 24 hours. Calcium levels were monitored daily, and iPTH was measured one and three days after surgery. Patients were monitored for symptoms daily for at least three days after surgery. All patients were reassessed after one week and at one, three, and six months. Calcium and iPTH levels were measured at each follow-up visit.

Results: The 90 patients were predominantly women (73 of 90) and had an average age of 47 years. The supplement and nonsupplement groups were almost identical in all important respects, including the number of malignant cases (38 and 37, respectively) and types of procedures performed. Overall, 14 patients (16 percent) developed symptomatic hypocalcemia after surgery. The rates were 7 percent in those receiving supplements and 24 percent in the control group. The difference between the groups was statistically significant. The three symptomatic patients in the supplement group had mild symptoms. Conversely, severe symptoms occurred in the control group, including carpopedal spasms in three patients. Five patients in the control group received intravenous calcium, but no patients in the supplement group required this therapy. Based on laboratory values, hypocalcemia developed in 36 percent of control participants and 13 percent of patients receiving supplements. This difference was statistically significant. The two groups did not differ in preoperative or postoperative iPTH levels. No adverse effects or hypercalcemia developed in patients receiving supplements.

Conclusion: The authors conclude that routine supplementation with calcium plus vitamin D effectively reduces hypocalcemic complications following thyroid surgery. They estimate that use of this simple and inexpensive measure could significantly reduce costs and decrease duration of hospitalization.

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