Congenital hypothyroidism (CH) is a condition that can present with a variety of signs and symptoms and requires specific investigations for diagnosis.
Signs and symptoms
- Common symptoms: In neonates, symptoms may include a large posterior fontanelle, large tongue, umbilical hernia, prolonged jaundice, constipation, lethargy, and/or hypothermia
- Associated anomalies: There is an increased prevalence of congenital renal and urologic anomalies in children with CH, suggesting the need for evaluation for these anomalies
Investigations
- Initial evaluation: A complete history, including prenatal maternal thyroid status, maternal medications, and family history, should be elicited. A complete physical examination is also recommended
- Confirmation of diagnosis: Confirmatory testing with serum free thyroxine (fT4) and thyroid-stimulating hormone (TSH) should be obtained as soon as possible after an abnormal neonatal screening result
- Evaluation for central hypothyroidism: If serum TSH is normal or low and serum fT4 is low on the confirmatory serum sample, further testing for possible central hypothyroidism is recommended . Central CH should be suspected if serum fT4 is low and TSH is low, normal, or slightly elevated
- Thyroid imaging: Thyroid imaging with either radioisotope scintigraphy (with or without perchlorate discharge test) or ultrasound, or both, is recommended . Thyroid ultrasound or scintigraphy can be considered to establish the etiology of CH
- Genetic testing: Genetic testing is recommended in patients with central CH . It is also recommended to consult with a geneticist in cases of central CH or CH associated with clinical features of a recognizable syndrome or an underlying genetic condition
- Evaluation for malformations: A careful examination for dysmorphic features suggestive of syndromic CH and for congenital malformations (particularly cardiac) is recommended in all infants with high TSH levels
In conclusion, CH presents with a variety of signs and symptoms and requires a comprehensive approach to diagnosis, including history taking, physical examination, confirmatory testing, and imaging studies. Genetic testing and evaluation for associated anomalies are also important components of the diagnostic process.