Children and young adults treated with amiodarone have a significant likelihood for development of thyroid dysfunction soon after treatment initiation, according to study results published in The Journal of Clinical Endocrinology & Metabolism.
The results suggest that patients treated with amiodarone should have thyroid function tested early and regularly.
Amiodarone-induced thyroid disease is not well classified in the pediatric population, and there are no evidence-based guidelines for thyroid function screening in pediatric patients who begin amiodarone therapy. The current retrospective study included chart data from children and young adults treated with amiodarone between 2007 and 2018 at the Children’s Hospital of Philadelphia (n=484). The researchers collected all available thyroid function test results (thyroid-stimulating hormone [TSH], thyroxine [T4], free T4, triiodothyronine [T3], and reverse T3).
Primary hypothyroidism was defined as TSH level >10 mIU/L, subclinical hypothyroidism as TSH level >5 and <10 mIU/L, and hyperthyroidism as TSH level <.1 mIU/L associated with an elevated free T4, T4, or T3 level.
Of all patients, 190 underwent thyroid function testing and were not receiving levothyroxine. Of these, 17.3% (n=33) had subclinical hypothyroidism and 13.7% (n=26) had hypothyroidism.
Of the patients with subclinical hypothyroidism, 63% (n=21) returned to normal thyroid function without thyroid hormone replacement. However, in those with hypothyroidism, only 26.9% (n=7) had spontaneous normalization of thyroid function. Most of the remaining patients were started on levothyroxine replacement therapy.
Hyperthyroidism was observed in 2.1% (n=4) of patients, and there were no patients with subclinical hyperthyroidism. Of those with hyperthyroidism, only 1 had spontaneous return to normal thyroid function. The other patients received methimazole.
Mortality rate was high among the study population, with 14 of 63 patients who had abnormal thyroid function dying of primary cardiac disease or related complications.
“Given the high incidence of thyroid dysfunction and its early onset in pediatric patients, we recommend that a complete thyroid function panel be measured at baseline and then at weekly intervals for the first five weeks after initiation of amiodarone,” wrote the researchers.
“Future prospective studies systematically monitoring thyroid function in pediatric patients treated with amiodarone are needed to more accurately define the monitoring and treatment recommendation in this patient population,” they concluded.
Barrett B, Hawkes CP, Isaza A, Bauer AJ. The effects of amiodarone on thyroid function in pediatric and young adult patients [published online July 30, 2019]. J Clin Endocrinol Metab. doi:10.1210/jc.2019-00990