Central Congenital Hypothyroidism Detected by Neonatal Screening in Sapporo, Japan (2000–2004): It’s Prevalence and Clinical Characteristics

In Sapporo, Japan, a neonatal screening program for congenital hypothyroidism(CH) has employed measurement of free thyroxine (T4) and TSH in the same filter-paperblood spot. This system has enabled us to identify primary CH and central CH during theneonatal period. The aim of this study was to clarify the prevalence and clinicalcharacteristics of central CH. For this purpose, the screening program requested serumfrom infants with free T4 concentrations below the cut off value regardless of the TSHlevels. Between January 2000 and December 2004, 83,232 newborns were screened and sixcentral CH patients were detected as a result of follow-up of low free T4 and non-elevatedTSH screening (1:13,872). This frequency is higher than in other studies. Four patientsshowed multiple pituitary hormone deficiency with pituitary malformations on magneticresonance imaging. One patient was diagnosed as having Prader-Willie syndrome. Theremaining patient was considered to have isolated central CH. Our study demonstrated thatthe frequency of central CH is 1:13,872. Free T4 measurement would also be advantageous inearly recognition of multiple pituitary hormone deficiency.