ESPE Abstracts

Introduction: Although newborn screening (NBS) for congenital hypothyroidism (CH) in Japan started more than 40 years ago, the prevalence of CH remains unclear. Prevalence estimations among the NBS-positive CH individuals include those with transient hypothyroidism and transient hyperthyrotropinemia, and re-evaluation with increasing age is necessary to clarify the actual incidence. Thus, we re-evaluated the incidence of permanent CH.

Subjects and Methods: Of the 106,114 patients who underwent NBS in the Niigata Prefecture, Japan, between April 2002 and March 2006, 116 were examined further due to high thyroid-stimulating hormone levels (≥ 8 mIU/l) and were included in the study. We retrospectively evaluated their levothyroxine sodium (LT4) replacement therapy status from the first visit to 15 years of age.

Discussion and Conclusions: Although this was not a nationwide survey, this is the first study to clarify the true prevalence of permanent CH in Japan. This study was strengthened by uniform data, as a single institution managed almost all the CH screenings in the Niigata Prefecture and transient CH was excluded from long-term follow-up until the age of 15 years. In our study, approximately 60% of the LT4 replacement patients discontinued treatment by 15 years of age. From these results, the prevalence of permanent CH in the Niigata Prefecture during this period was 1 in 2,500–3,500 children.