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Hypothyroidism common after hemithyroidectomy
Hypothyroidism occurs in more patients after hemithyroidectomy than previously believed; however, thyroid hormone replacement is required in only a small portion of the cases, study findings show.
“The higher incidence [of hypothyroidism] noted in the present study may be due to the prospective detection of biochemical hypothyroidism by using the standardized follow-up protocol after surgery, which included the regular measurement of thyroid function even in patients without any signs/symptoms of hypothyroidism,” the researchers wrote.
Dongbin Ahn, MD, a surgeon in the department of otolaryngology-head and neck surgery at Kyungpook National University in Korea, and colleagues evaluated 405 adults (mean age, 47.4 years) who underwent hemithyroidectomy between August 2004 and February 2011 at Kyungpook National University to determine the clinical characteristics of hypothyroidism after the surgery along with incidence and risk factors. Follow-up was conducted for a mean of 56.4 months.
More than half of all participants (55.8%) developed hypothyroidism after surgery. Of these, 84.5% were diagnosed within 3 months after surgery and 91.2% within 9 months; 8.8% had hypothyroidism more than 9 months after surgery.
Independent risk factors for the development of hypothyroidism included having a thyroid-stimulating hormone level of at least 2 mIU/L (P < .001) and coexisting Hashimoto’s thyroiditis (P = .022).
Spontaneous recovery of subclinical hypothyroidism occurred in 67.1% of 222 participants with subclinical hypothyroidism. Independent risk factors for unrecovered subclinical hypothyroidism after hemithyroidectomy included age 45 years or older (P = .007) and a preoperative TSH level of 2.6 mIU/L or more (P = .004).
Only 14% of all participants required levothyroxine replacement after hemithyroidectomy.
“To ensure that at least 90% of cases of postoperative hypothyroidism are detected, we recommend that regular thyroid function measurements should be performed for a minimum of 9 months after surgery in patients undergoing hemithyroidectomy,” the researchers wrote. “In addition, further follow-up of thyroid function is required in selective patients, particularly those with preoperative TSH 2 mIU/L and coexistence of Hashimoto’s thyroiditis.” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.