Congenital hypothyroidism

Alternative name Primary congenital hypothyroidism
About the condition Congenital hypothyroidism is an endocrine disorder. It is a condition that is caused by under-activity of the thyroid gland, which results in low levels of thyroid hormones. These hormones play an important role in body metabolism and their deficiency can cause intellectual and physical disability.
Inheritance Most cases are sporadic. However, about 10% of cases result from inherited enzyme defects within the thyroid gland.
Year screening occurred in WA  1981
Incidence in WA 1 in 3,000 births
  • No thyroid gland (athyrosis)
  • Small maldescended gland
  • Iodination defect
Symptoms if untreated Signs of hypothyroidism often do not appear until the infant is 3–4 months of age. Affected infants are likely to have already suffered irreversible brain damage before signs of the condition begin to appear. Many times the early diagnosis relies almost solely on the results of newborn screening. Other symptoms of the condition include:
  • Prolonged neonatal jaundice
  • Feeding problems, FTT, constipation
  • Lethargy, hypotonia
  • Coarse facial features, thick tongue
  • Hoarse cry
  • Distended abdomen, umbilical hernia
  • Intellectual disability
  • Physical disability
If detected early and treated, the child will develop normally.
Metabolites on bloodspot screening Increased thyroid stimulating hormone (TSH).
Diagnostic tests
  • Plasma TSH and free T4
  • A scan of the thyroid gland is also sometimes performed
Treatment Daily treatment with thyroid hormone tablets results in normal growth and development.
Screening issues The screening results may be affected by maternal thyroid disease and medication, as well as iodine excess or deficiency.