Thyroidectomy, Hypothyroidism, Risk Factors, Relative Risk

The issue of hypothyroidism following thyroidectomy is still under debate. Currently all patients receive thyroid hormones while most of them really do not require such treatment. This study looks at the incidence of hypothyroidism among patients who underwent thyroidectomy in a major referral hospital and examines possible risk factors.

102 patients who underwent thyroidectomy in Shariati Hospital were investigated for their thyroid function profile on five occasions: just before surgery and after surgery and then three times, on a 3-monthly interval, for one year. All patients whose tests indicated hypothyroidism, were given hormone replacement therapy. The treatment continued for 3 months after normalization of the tests.

Thirty men and 72 women were included in this study. Mean age of participants was 39±13.6 years (males: 40.5±14.2 and females: 38.4±5.1 years). Thirty-six patients developed hypothyroidism (35.2%) occurring on an average 5±3.2 months after surgery. Increased weight, operation type, histopathologic type (Grave's disease and adenomatous goiter), underlying diseases (Grave's disease and toxic multinodular goiter) and their duration, lymphocytic infiltration and use of levothyroxine before surgery were found to be associated with the incidence of hypothyroidism. On the contrary, no association between the occurrence of hypothyroidism and gender, grade of thyromegaly, post-surgical complications or immediate pre-surgical TSH level was seen.

The investigation can serve as a pilot study for more extensive studies examing the issue in the future. Indicators such as Grave's disease and lymphocytic infiltration in pathologic specimens may be used to predict the occurrence of hypothyroidism in patients undergoing thyroidectomy and limit the unnecessary usage of thyroid hormones.