Thyroid Function Screening in Children With Alopecia Areata

To the Editor In their recent article in JAMA Dermatology, Patel et al describe the prevalence of thyroid disorders among subgroups of children with alopecia areata (eg, those with Down syndrome), and interpret the findings as justification for screening such children. Unfortunately, the authors did not attempt to exclude children presenting with symptoms of thyroid dysfunction (eg, heat or cold intolerance, fatigue, growth abnormalities). Indeed, a category of thyroid dysfunction among the 59 patients with abnormal results was "subclinical thyroid dysfunction," implying that the other patients may have had clinical signs or symptoms of thyroid disease. Since screening, by definition, is conducted among asymptomatic individuals, the results reported by Patel et al cannot be interpreted to support or refute screening guidelines. Children with symptoms of thyroid dysfunction are more likely to receive thyroid function tests and are also more likely to have thyroid dysfunction; therefore, the true prevalence of thyroid disorders among asymptomatic children with alopecia areata who receive thyroid screening is expected to be lower than the estimates in this study. Whether the true prevalence is high enough in certain subgroups to justify screening cannot be determined from the data presented.