Orris

Hypothyroidism in newborns according to age criteria

  1. Definition and timing
    • Congenital hypothyroidism present at birth
    • Transient hypothyroidism in the neonatal period
    • Hypothyroidism acquired later in infancy
  2. Age-specific thyroid physiology and laboratory interpretation
    • Normal neonatal TSH surge in the first 24 to 48 hours
    • Appropriate timing of newborn screening
    • Age-adjusted reference ranges for TSH and free T4
  3. Clinical features by age
    • First days of life: often few or no clear signs
    • First weeks: prolonged jaundice, poor feeding, lethargy, constipation, hypotonia
    • Later infancy: poor growth and neurodevelopmental delay if untreated
  4. Screening and diagnostic age criteria
    • When to collect newborn screening samples
    • When to repeat testing in preterm, low-birth-weight, or sick newborns
    • How delayed TSH elevation is identified
  5. Management by age at diagnosis
    • Urgent treatment in confirmed congenital hypothyroidism
    • Follow-up testing and distinguishing permanent from transient disease
High-level overview:
Hypothyroidism in a newborn is usually discussed as congenital hypothyroidism, detected through newborn screening. Interpretation must be age-specific because TSH rises physiologically soon after delivery and then falls over the next few days. Therefore, a sample taken too early can be misleading.
Most affected newborns appear normal initially because maternal thyroid hormone crosses the placenta. Symptoms usually become more noticeable over the following weeks. The main clinical priority is early detection and prompt levothyroxine treatment, because untreated deficiency can impair brain development.
Which would you like next: (1) age-wise TSH/free T4 values, (2) clinical signs by age, (3) newborn-screening timing and repeat testing, or (4) treatment and follow-up?
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