Hypothyroidism After Hemithyroidectomy: Incidence, Risk Factors, Natural History and Management

Thyroid lobectomy or hemithyroidectomy is considered an adequate treatment for several thyroid diseases such as large benign nodules, follicular neoplasm, and some suspected malignancies. Thyroid lobectomy theoretically preserves sufficient functioning native thyroid tissue for patients to keep euthyroid status postoperatively without the need for thyroid hormone replacement. Still, it is known that some patients who have undergone hemithyroidectomy will require thyroid hormone replacement because they have developed hypothyroidism, which is commonly diagnosed as a result of elevated levels of thyroidstimulating hormone (TSH). Currently, the incidence and risk of hypothyroidism in patients undergoing partial thyroidectomy remains unclear. Several studies about thyroid function after hemithyroidectomy for benign thyroid disease have been published. The reported incidence of hypothyroidism ranges from 5% to 49%, with most between 15-30%. The incidence rates vary widely depending on the follow-up period and on how hypothyroidism is defined by authors. These variations have led to our interest in defining uniform criteria for diagnosis and treatment of postoperative hypothyroidism, thereby identifying patients at the greatest risk of requiring long-term thyroid hormone replacement.