Many clinicians and laboratories check TSH alone as the initial test for thyroid problems and then only add a Free T4 measurement if the TSH is abnormal, referred to as “reflex” testing. The goal of this study was to evaluate different TSH cutoffs leading to reflex Free T4 testing, with the purpose to determine whether a widened normal range could decrease the need for additional Free T4 testing and not lead to missing cases of thyroid problems.