Objectives: To determine the prevalence and possible risk factors of postoperative hypothyroidism after hemithyroidectomy.
Methods: Medical records of patients who underwent hemithyroidectomy from January 2013 to December 2020 at Somdejphrajaotaksinmaharaj Hospital were retrospectively reviewed. Patients with preoperative euthyroid status were included. The postoperative thyroid function tests were obtained and prevalence of postoperative hypothyroidism was assessed afterwards. The potential risk factors associated with postoperative hypothyroidism were analyzed using Chi-square test or Fischer's exact test for categorical variables, and independent student t-test or Mann-Whitney U test for continuous variables.
Results: A total of 72 patients were included, of which 63 (87.5%) were female and 9 (12.5%) were male, with mean age of 47.69 ± 11.00 years. Postoperative hypothyroidism occurred in 22 patients (30.6%) at 6-8 weeks after surgery, including 8 (11.1%) with overt hypothyroidism and 14 (19.4%) with subclinical hypothyroidism. The mean preoperative serum thyroid stimulating hormone (TSH) level was significantly higher in the hypothyroid group than in the euthyroid group (p=0.026). Moreover, patients with preoperative serum TSH level higher than 1.5 mIU/L posed 4-fold higher risk for the development of hypothyroidism following hemithyroidectomy (OR 4.00; 95%CI=1.35-11.85, p=0.010).
Conclusions: Hypothyroidism was relatively common complication of hemithyroidectomy. The prevalence of postoperative hypothyroidism in this study was 30.4%. Also, preoperative serum TSH level that greater than 1.5 mIU/L was identified as risk factor associated with postoperative hypothyroidism after hemithyroidectomy. These finding suggests the need for proper preoperative counseling and effective postoperative follow-up protocol for the patients who are scheduled for hemithyroidectomy, particularly in whom with the risk factor of postoperative hypothyroidism.
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