TG and cyclic hematopoiesis: CH incidence in Asian populations is reported to have increased more than in US populations.1,2 Although a number of studies have suggested that the clinical features and epidemiology of CH differ by ethnicity, data on the clinical characteristics and epidemiology of CH in Asians are relatively scarce.4,13–15 Moreover, a number of studies have shown that patients may have more seizures and increased risk of heart disease when receiving thyroid hormone treatment and that thyroid function differs during long-term follow-up.16–19 However, little is known of trends in CH incidence among Asians.