Factors Associated with Hypothyroidism following Hemithyroidectomy: A Prospective Study

Abstract

Objectives:

Analyze factors associated with hypothyroidism following hemithyroidectomy.

Methods:

Prospective study at Chiang Mai University Hospital, Thailand. Patients who were scheduled for a hemithyroidectomy between September 2010 and April 2012 were recruited for the study. Demographic data, pre- and post-operative thyroid function tests, resected side, weight and pathological diagnosis of resected thyroids between the euthyroid and hypothyroid groups were analyzed.

Results:

Of 50 cases, 11 cases with documented malignancy, or who required a total thyroidectomy, or who were lost to follow up were excluded. Thirty-nine cases included seven males and 32 females, age ranged from 19 to 71 years (46.9±13.8 years). The resected thyroids were from the left (25) and the right (14). The pathology reports were as follows: adenomatous goiter (67%), follicular adenoma (20%), colloid cyst (5%), chronic lymphocytic thyroiditis (3%), and others (5%). Eight cases (20.5%) had hypothyroidism postoperatively at eight to ten weeks. The pre-operative thyroid-stimulating hormone (TSH) level of the hypothyroid group was normal but significantly less than in the euthyroid group (P = 0.009). Age, gender, pre-operative free T4 and free T3, weight and resected side showed no difference between the two groups.

Conclusions:

One-fifth of the hemithyroidectomy patients developed hypothyroidism within eight to ten weeks post-operatively. Clinicians should be aware of post-operative hypothyroidism and provide prompt treatment, particularly in patients with a pre-operative high normal TSH level.