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Congenital hyperthyroidism
H Krude1, H Biebermann, H P Krohn
1Department of Pediatrics, Virchow-Klinikum, Humboldt University, Berlin, Germany.
Insights
Congenital hyperthyroidism is a rare but serious condition impacting fetal and infant development. Molecular diagnostics now differentiate between autoimmune and non-immune causes for tailored treatment.
Area of Science:
- Endocrinology
- Pediatrics
- Genetics
Background:
- Congenital hyperthyroidism, though rare, poses significant risks to fetal and postnatal development.
- Untreated or severe cases can lead to critical outcomes including cardiac failure and high mortality rates.
Observation:
- Fetal manifestations include tachycardia, arrhythmia, growth retardation, and prematurity.
- Postnatal signs encompass irritability, hypertension, poor weight gain, and thyroid enlargement.
- Craniosynostosis and severe developmental delay are key complications of persistent neonatal hyperthyroidism.
Findings:
- Autoimmune congenital hyperthyroidism results from transplacental passage of maternal thyroid-stimulating antibodies.
- Non-immune congenital hyperthyroidism is linked to activating mutations in the thyroid-stimulating hormone receptor.
- Molecular diagnostics enable differentiation between these two etiological groups.
Implications:
- Accurate diagnosis of congenital hyperthyroidism is crucial for preventing severe developmental consequences.
- Distinguishing between autoimmune and non-immune forms allows for optimized, individualized treatment strategies.
- Advances in molecular diagnostics offer improved management and outcomes for affected infants.
Abstract:
Congenital hyperthyroidism is a very rare disease. But, for each affected child it has to be considered as a serious condition because of the negative impact of hyperthyroidism on fetal and postnatal development. If the manifestation occurs during fetal life tachycardia, cardiac arrhythmia, growth retardation and, most significant, prematurity are the consequences. Postnatal signs of hyperthyroidism are irritability, tachycardia, hypertension, poor weight gain and thyroid enlargement. Even cardiac failure may occur if hyperthyroidism is severe and treatment not adequate which explains the high early mortality rate of 16%. The main complication of persistent hyperthyroidism in the neonatal period and during infancy is craniosynostosis. Severe developmental delay or even mental retardation can be the consequence of inadequate high T4-levels during fetal and neonatal life. Congenital hyperthyroidism was first recognized in infants born to mothers with Graves' disease. The description of transplacental passage of the maternal thyroid stimulating antibodies elucidated the molecular mechanism in this major group of patients with "autoimmune congenital hyperthyroidism". In contrast to this transient, self-limited character of "autoimmune congenital hyperthyroidism", due to the clearance of maternal antibodies from the infant's circulation, some cases of persistent congenital hyperthyroidism without signs of thyroid autoimmunity have been recognized. Activating mutations in the thyroid-stimulating hormone receptor were described recently as the underlying molecular pathogenesis in this group of "non-immune congenital hyperthyroidism". Therefore the possibility of a molecular differential diagnosis of both groups of congenital hyperthyroidism now exists and opens the opportunity of optimal treatment for each patient.