Hypothyroidism following hemithyroidectomy for benign nontoxic thyroid disease

Abstract

Hypothyroidism following hemithyroidectomy for benign nontoxic thyroid disease is an underappreciated phenomenon. Up until recently, it was common practice for physicians to place post-hemithyroidectomy patients on thyroid suppression therapy during the immediate postoperative period. That practice began to fall out of favor as a result of two developments: (1) the publication of data that put into question the efficacy of levothyroxine therapy for preventing recurrent disease or thyroid growth and (2) a heightened awareness of the morbidity associated with levothyroxine. We conducted a retrospective chart-review study of 58 patients with benign nontoxic thyroid disease who had undergone hemithyroidectomy from 1994 through 2003 at one institution. Of these 58 patients, 14 (24.1%) had become hypothyroid after surgery, including 7 who had been so diagnosed 1 month postoperatively and 6 at 2 months. The remaining 44 patients were euthyroid. The mean preoperative serum thyroid-stimulating hormone (TSH) levels in the hypothyroid and the euthyroid groups were 2.39 and 1.07 μIU/ml, respectively - a statistically significant difference (p < 0.0001). A tissue diagnosis consistent with chronic inflammation (lymphocytic thyroiditis or Hashimoto's thyroiditis) was found in 50.0% of the hypothyroid patients, compared with only 6.8% of the euthyroid patients - again, a significant difference (p < 0.001). No significant difference was seen between the two groups with respect to age, sex, or the weight of the resected gland. We conclude that hypothyroidism after hemithyroidectomy is not an uncommon occurrence. Apparent risk factors include a high mean preoperative serum TSH level and tissue pathology consistent with chronic inflammation. It may be wise to follow patients with these identifiable risk factors more closely during the postoperative period; monitoring should include scheduled serial serum TSH draws.