Effect of thyroid hormone replacement therapy on mortality rate in patients undergoing total or hemithyroidectomy for...

Thyroid surgery for benign non-toxic nodular goitre is a common endocrine surgical procedure. It is not known whether thyroid hormone replacement therapy following surgery for benign thyroid disease influences mortality or morbidity rates.

A retrospective observational study was conducted using national registries in Sweden. Overall mortality and morbidity rates were compared for patients with or without thyroid hormone replacement therapy in patients operated on with hemithyroidectomy or total thyroidectomy for a diagnosis of benign non-toxic nodular goitre.

Between 1 July 2006 and 31 December 2017, 5573 patients were included, 1644 (29.5%) patients were operated on with total thyroidectomy and 3929 patients with hemithyroidectomy. In the hemithyroidectomy group, 1369 (34.8%) patients were prescribed thyroid hormone replacement therapy in the follow-up. The patients who underwent hemithyroidectomy and did not use thyroid hormone replacement therapy in the follow-up had a standard mortality ratio of 1.31 (95% confidence interval, 1.09-1.54). The mortality ratio was not increased in patients who underwent total thyroidectomy or hemithyroidectomy and used thyroid hormone replacement therapy. The risk of death analysed by multivariable Cox regression for patients operated on with hemithyroidectomy without later thyroid hormone replacement therapy, adjusted for age and sex, showed an increased hazard ratio of 1.65 (1.19-2.30) compared with hemithyroidectomy with hormone replacement therapy.

Patients subjected to hemithyroidectomy without later hormone replacement therapy had a 30% higher risk of death compared with the normal Swedish population and a 65% increased risk of death compared with patients undergoing hemithyroidectomy with postoperative hormone replacement therapy.