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Removing the whole thyroid lessens the chance of hyperthyroidism recurrence in Graves' disease compared with partial thyroidectomy, but it also leads to increased temporary hypoparathyroidism, researchers found.

In a meta-analysis, total thyroidectomy was associated with a significant reduction in recurrent hyperthyroidism compared with bilateral subtotal thyroidectomy (P<0.01), reported Zhenjie Liu, MD, of Zhejiang Cancer Hospital in Hangzhou, China, and colleagues online in Clinical Endocrinology.

It was, however, found to increase the risk of temporary hypoparathyroidism (P<0.01), they added. But other outcomes, including recurrent laryngeal nerve palsy and bleeding, were similar between operations.

Liu and colleagues wrote that the findings suggest total thyroidectomy "should be proposed for the treatment of Graves' disease."

Thyroidectomy is an option for treating Graves' disease if anti-thyroid drugs fail to induce remission. It's generally preferred by physicians in Europe and Asia, while endocrinologists in the U.S. favor radioactive iodine therapy.

But studies have shown that hyperthyroidism relapse rates are lowest for surgical patients, and surgery is an ideal course of therapy for some forms of the condition, including Graves' eye disease, the researchers said.

Still, there's controversy over whether to perform total thyroidectomy or subtotal thyroidectomy in these patients. Subtotal thyroidectomy was the standard until about a decade ago, when more surgeons started to prefer total thyroidectomy, despite the concern that a more radical operation could increase complication rates.

To compare the therapies, Liu and colleagues conducted a meta-analysis of randomized controlled trials looking at both types of surgery.

They focused on two primary outcomes -- recurrent hyperthyroidism and ophthalmopathy progression -- as well as several secondary endpoints, including temporary and permanent hypoparathyroidism, temporary and permanent recurrent laryngeal nerve palsy, and postoperative bleeding.

Overall, they evaluated four trials totaling 674 patients with Graves' disease -- 342 of whom had total thyroidectomy, 332 who'd had subtotal thyroidectomy.

They found that total thyroidectomy was associated with a significant reduction in recurrent hyperthyroidism compared with the subtotal procedure (relative risk 0.14, 95% CI 0.05 to 0.41).

"It seems that leaving any tissue could be a risk of recurrence, just as some endocrine surgeons believe," the researchers wrote.

However, overall rates of ophthalmopathy progression were similar between the two groups.

In terms of secondary outcomes, Liu and colleagues found a significantly increased risk of temporary hypoparathyroidism with total thyroidectomy (RR 2.66, 95% CI 1.89 to 3.73,), but there was no significant difference between procedures in terms of permanent hypoparathyroidism (RR 2.30, 95% CI 0.78 to 6.76, P=0.013).

Nor was there any differences between groups in terms of temporary or permanent recurrent laryngeal nerve palsy (RR 1.08, 95% CI 0.47 to 2.48, P=0.085)), or postoperative bleeding (RR 0.32, 95% CI 0.05 to 1.96, P=0.022), they reported.

The study was limited because it was based on a small number of trials with high heterogeneity.

Liu and colleagues concluded that because total thyroidectomy reduces the risk of recurrent hyperthyroidism, it should be the proposed treatment for Graves' disease.

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