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Thyroid hormone resistance detected by routine neonatal screening.
Léa Maria Zanini Maciel1, Patrícia Künzle Ribeiro Magalhães
1Division of Endocrinology, Department of Clinical Medicine, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, SP, Brazil. lmzmacie@fmrp.usp.br
Arquivos Brasileiros De Endocrinologia E Metabologia
|February 23, 2011
Summary
Neonatal screening identified resistance to thyroid hormone syndrome (RTH) in a Brazilian infant. Molecular analysis confirmed a specific gene mutation, highlighting the importance of careful interpretation of thyroid hormone levels.
Area of Science:
- Endocrinology
- Genetics
- Neonatal Medicine
Background:
- Resistance to thyroid hormone syndrome (RTH) is a rare genetic disorder affecting thyroid hormone metabolism.
- Early diagnosis is crucial for managing potential health complications.
Observation:
- A Brazilian infant detected via neonatal screening presented with elevated TSH levels.
- Subsequent laboratory tests revealed normal TSH but elevated total T4 with normal free T4 and T3 levels.
- A familial study identified RTH in the infant's father, sister, and paternal grandfather, with goiter present in all affected relatives.
Findings:
- Direct sequencing of the beta thyroid hormone receptor gene identified the c.1357C>A (P453T) mutation, confirming RTH.
- The father had a prior misdiagnosis of hyperthyroidism, underscoring diagnostic challenges.
- The study highlights the utility of clinical evaluation and precise interpretation of thyroid hormone concentrations in diagnosing RTH.
Implications:
- This case emphasizes the effectiveness of neonatal screening in identifying RTH.
- Accurate interpretation of thyroid function tests, particularly total T4 and free T4, is vital for diagnosing RTH in newborns.
- Understanding the genetic basis and clinical presentation of RTH aids in family screening and management.
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