Subclinical hypothyroidism following hemithyroidectomy: a simple risk-scoring system using age and preoperative thyrotropin level.

Hypothyroidism can be a complication after a hemithyroidectomy. The aim of this study was to determine the incidence and risk factors of hypothyroidism after a hemithyroidectomy. We also recommend a risk-scoring system that can predict post-hemithyroidectomy hypothyroidism before surgery. Among 260 patients who underwent hemithyroidectomy from January to June 2005, a total of 233 were euthryoid preoperatively and were followed for more than 3 years. Biochemical subclinical hypothyroidism developed in 57 patients (24.4%). Patients who developed postoperative hypothyroidism showed higher preoperative thyroid stimulation hormone (TSH) levels and older age. A risk-scoring system was calculated by summing the score of these 2 factors (preoperative TSH level and age). The incidences of hypothyroidism were 3, 20, 39, and 70% according to the risk scores of 0, 1, 2 and 3, respectively. Potential risk of postoperative hypothyroidism should be discussed with patients before surgery.