Hypothyroidism, congenital

E03.1

DESCRIPTION

Congenital deficiency of thyroid hormone due to:

  • aplasia/hypoplasia or ectopia of the thyroid gland,
  • defects in thyroid hormone biosynthesis, or
  • intrauterine exposure to antithyroid medicines.

Congenital hypothyroidism is one of the common treatable causes of preventable mental retardation in children. Congenital hypothyroidism must be treated as early as possible to avoid intellectual impairment.

Symptoms and signs in neonates are unreliable, thus screening is essential for ensuring early intervention.

DIAGNOSTIC CRITERIA

Clinical

  • Prolonged unconjugated hyperbilirubinaemia.
  • Oedema of the extremities and genitals.
  • Feeding difficulties.
  • Bradycardia.
  • Lethargy.
  • Anaemia.
  • Somnolence.
  • Apnoeic episodes.
  • Abdominal distension.
  • Coarse cry.
  • Umbilical hernia.
  • Constipation.
  • Subnormal temperature.
  • Wide open fontanelles.
  • Periorbital oedema.
  • Enlarged tongue.
  • Delayed dentition.
  • Short and thick neck.
  • Broad hands.
  • Dry skin.
  • Coarse, scanty hair.
  • Hypotonia.
  • Hoarse voice and goitre.
  • Delayed physical and mental development.

Investigations

  • When suspected, perform TSH test.
    • If elevated perform a free T₄.

Delay in diagnosis and treatment is associated with irreversible neurodevelopmental damage.

GENERAL AND SUPPORTIVE MEASURES

  • Routine screening of all newborns for congenital hypothyroidism.
  • Growth and neurodevelopmental assessment.
  • Regular follow up.

MEDICINE TREATMENT

For neonates, started as soon as possible, ideally within the first three weeks after birth:

  • Levothyroxine, oral, 10–15 mcg/kg as a single daily dose on an empty stomach.
    • Adjust dosage to blood levels of T₄ (in the upper half of the reference range) and normalise the TSH (between 0.5–2 mU/L), especially in the first 3 years of life. Check TSH only 6 weeks after adjusting the thyroxine dose.
    • Continue treatment indefinitely.

REFERRAL

  • All patients for confirmation of diagnosis but initiation of therapy should not be delayed.