2018 Volume 111 Issue 1 Pages 61-65
Objective: Hypothyroidism is a noteworthy complication after hemithyroidectomy, and its reported frequency varies widely in the range of 22%–56%. If we can predict thyroid function after hemithyroidectomy, it would help us to explain the risk of post-operative hypothyroidism to the patient.
Method: We reviewed the data of 93 patients who underwent hemithyroidectomy between January 2013 and December 2015. Patients with pre-operative hypothyroidism or receiving TSH suppression therapy postoperatively were excluded. We investigated the prevalence of post-operative hypothyroidism, the interval between surgery and the development of hypothyroidism, the risk factors for hypothyroidism, and the need for thyroid hormone replacement therapy in the study subjects.
Results: Post-operative hypothyroidism developed in 36 patients (39%). It was detected after an interval of less than one month in 23 patients, less than 6 months in 4 patients, less than 12 months in 5 patients, and more than 12 months in 4 patients. Among the 35 patients with subclinical hypothyroidism, 21 exhibited permanent hypothyroidism, and in most, the interval between surgery and the development of hypothyroidism was short. Eighteen patients required thyroid hormone replacement therapy. Only pre-operative serum TSH was identified as being significantly associated with the development of hypothyroidism (p<0.01). On the other hand, the age, sex, histology (benign/malignant), operation side, and presence/absence of anti-Tg antibody and anti TPO antibody were not found to be significant. Pre-operative TSH>1.95 was the effective cut-off value for determining the need for thyroid hormone replacement therapy.
Conclusion: Post-operative hypothyroidism developed in about 40% of the patients, with 20% requiring thyroid hormone replacement therapy. Patients who developed hypothyroidism within a short interval after the hemithyroidectomy were more likely to need hormone replacement therapy. Pre-operative serum TSH level was a good predictor of the risk of post-operative hypothyroidism and of the need for hormone replacement therapy. These results lend support to the recommendation for close thyroid function follow-up after surgery in patients with relatively high pre-operative serum TSH levels within the normal range.
