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Updated: Jun 22, 2026
08:33
An Ex vivo Culture System to Study Thyroid Development
Published on: June 6, 2014
Elevated free thyroxine levels detected by a neonatal screening system.
Toshihiro Tajima1, Wakako Jo, Kaori Fujikura
1Department of Pediatrics, Hokkaido University School of Medicine, Sapporo, Hokkaido 060-8635, Japan. tajeari@med.hokudai.ac.jp
Pediatric Research
|June 23, 2009
Summary
Neonatal screening in Sapporo identified hyperthyroxinemia, including rare conditions like resistance of thyroid hormone (RTH) and familial dysalbuminemic hyperthyroxinemia (FDH). The system aids early detection of these thyroid disorders in newborns.
Area of Science:
- Endocrinology
- Neonatal Medicine
- Genetics
Background:
- Neonatal screening for congenital hypothyroidism in Sapporo utilizes filter-paper blood spot measurements of free thyroxine (T4) and thyroid-stimulating hormone (TSH).
- This established screening protocol has also proven effective in identifying hyperthyroxinemic diseases in newborns.
Purpose of the Study:
- To evaluate the effectiveness of the existing neonatal screening program in identifying various causes of hyperthyroxinemia.
- To assess the diagnostic yield of screening for elevated free thyroxine (T4) in detecting specific thyroid-related conditions in neonates.
Main Methods:
- Screening of 83,232 newborns between January 2000 and December 2006 using filter-paper blood spots.
- Analysis of free thyroxine (T4) levels, with neonates showing elevated free T4 (>4.0 ng/dL) undergoing further study.
- Diagnostic confirmation through clinical evaluation, thyroid function tests, and genetic analysis (thyroid hormone receptor beta gene) for specific conditions.
Main Results:
- Eleven infants exhibited persistent hyperthyroxinemia.
- Diagnoses included one case of familial dysalbuminemic hyperthyroxinemia (FDH), two cases of resistance of thyroid hormone (RTH) confirmed by genetic analysis, and eight cases of neonatal Graves' disease (NGD).
- The screening identified one unrecognized case of NGD in a pregnancy where the mother was not treated with antithyroid drugs.
Conclusions:
- The neonatal screening system effectively enables early awareness and diagnosis of rare conditions such as RTH and FDH.
- While beneficial for detecting RTH and FDH, the screening's added value for Graves' disease is limited due to routine management of pregnant mothers with this condition.
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