Mass screening of newborns for congenital hypothyroidism of central origin by free thyroxine measurement of blood samples on filter paper

Abstract

Objective: To evaluate the effectiveness of mass screening of newborns for congenital hypothyroidism of central origin (CH-C) by measurement of free thyroxine (FT 4 ) and thyroid-stimulating hormone (TSH). Design: Questionnaire-based survey of CH-C patients born between 1999 and 2008 in Kanagawa prefecture, Japan. Methods: TSH and FT 4 levels in dried blood spots on filter paper were measured using ELISA kits, and CH-C was diagnosed at FT 4 levels below a cutoff of 0.7 ng/dl (9.0 pmol/l). Survey results were collated with the database created by the screening organizer.

Overall usefulness of newborn screening for congenital hypothyroidism by using free thyroxine measurement

“…Screening for CH-C was formerly criticized as inefficient because of the rarity of CH-C, but it is now recognized that CH-C is more prevalent than previously thought [6,21,22]. Following the inclusion of transient CH-C and CH-T with delayed TSH elevation as the target entities for screening with FT4 measurement, this system may be considered to be more efficient than currently thought.…”

“…As we previously reported [6], 24 CH-C patients who had been born in Kanagawa Prefecture between 1999 and 2008 were identified, among whom 13 patients had a positive screening result for FT4 level (<0.7 ng/dL) ( Table 1). Of these 13 patients, 12 were identified solely through newborn screening, whereas the other patient with hypopituitarism was diagnosed after presenting with a shock state along with the measurement of a positive FT4 level result (0.58 ng/dL) during screening.…”

“…The details of our screening methods were described in a previous report [6]. In brief, the screening procedure is based on the determination of TSH and FT4 levels in dried blood spots obtained 4-7 days (median, 5 days) after birth.…”

“…The first step in the data collection was conducting a survey regarding CH-C, as has been described previously [6]. In brief, through 2008 and 2009, a questionnaire was sent to all 139 hospitals with a pediatric section in Kanagawa Prefecture requesting them to report the number of and clinical data regarding the CH-C cases born between 1999 and 2008.…”

“…Screening of FT4 levels has enabled the detection of a significant number of cases of CH of central origin (CH-C), the incidence of which has been estimated to be 1 in 30,833 live births in our previous study [6].…”