Congenital Hypothyroidism: Clinical Case and Viva Q&A

Clinical Case of Congenital Hypothyroidism

Clinical Case: Congenital Hypothyroidism

A 3-week-old female infant is brought to the pediatric clinic by her parents for a routine check-up. The parents report the following observations:

• Prolonged jaundice since birth
• Difficulty feeding and poor weight gain
• Excessive sleepiness and reduced activity
• Constipation
• Hoarse cry

On physical examination, the pediatrician notes:

• Weight: 3.1 kg (below 3rd percentile)
• Length: 49 cm (10th percentile)
• Head circumference: 35 cm (25th percentile)
• Pale, dry skin with mottling
• Large fontanelles
• Macroglossia
• Umbilical hernia
• Hypotonia
• Delayed relaxation of deep tendon reflexes

The pediatrician orders thyroid function tests, which reveal:

• TSH: 150 mIU/L (normal range: 0.5-5 mIU/L)
• Free T4: 5 pmol/L (normal range: 10-25 pmol/L)

Based on these findings, a diagnosis of congenital hypothyroidism is made. The infant is immediately started on levothyroxine replacement therapy, and follow-up appointments are scheduled to monitor growth, development, and thyroid function.

Clinical Presentations of Congenital Hypothyroidism

Clinical Presentations of Congenital Hypothyroidism

1. Classic Presentation

   • Prolonged jaundice
   • Feeding difficulties
   • Constipation
   • Lethargy and somnolence
   • Large anterior and posterior fontanelles
   • Macroglossia
   • Umbilical hernia
   • Hypotonia
   • Cool, dry skin
   • Delayed reflexes

2. Mild or Subclinical Presentation

   • Subtle or absent clinical signs
   • Normal growth and development initially
   • Mild elevation of TSH with normal or slightly low T4
   • May be detected only through newborn screening

3. Severe Presentation (Untreated)

   • Profound intellectual disability
   • Severe growth retardation
   • Coarse facial features
   • Myxedematous skin changes
   • Persistent jaundice
   • Severe constipation
   • Hypothermia
   • Bradycardia

4. Transient Congenital Hypothyroidism

   • Temporary thyroid dysfunction
   • May present with mild symptoms
   • Often due to maternal factors (e.g., iodine deficiency or excess, anti-thyroid medications)
   • Thyroid function normalizes within weeks to months

5. Syndromic Presentation

   • Congenital hypothyroidism associated with other congenital anomalies
   • Examples: Pendred syndrome (hearing impairment), Bamforth-Lazarus syndrome (cleft palate)
   • May present with additional features specific to the syndrome

6. Late-Onset Presentation

   • Subtle signs appearing in infancy or early childhood
   • Mild developmental delay
   • Growth deceleration
   • Acquired goiter

7. Central Congenital Hypothyroidism

   • Due to pituitary or hypothalamic dysfunction
   • May present with additional pituitary hormone deficiencies
   • Normal or low TSH with low free T4
   • Often part of multiple pituitary hormone deficiency syndromes

Knowledge Check: Question and Answers for Medical Students & Professionals

This interactive quiz component covers essential viva questions and answers. It includes 30 high-yield viva questions with detailed answers.

Question 1 of 30

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