A 10-day-old neonate presents with prolonged jaundice, poor feeding, constipation, macroglossia, an umbilical hernia, and a large anterior fontanelle. Serum TSH is 85 mIU/L (normal <10) and free T4 is 0.4 ng/dL (low). What is the MOST URGENT treatment?
- A Iodine supplementation
- B Hydrocortisone to rule out concurrent adrenal insufficiency before starting thyroid hormone
- C Levothyroxine (L-T4) 10–15 mcg/kg/day orally as soon as possible ✓
- D Thyroid scan before initiating treatment
Correct answer: C. Levothyroxine (L-T4) 10–15 mcg/kg/day orally as soon as possible
Explanation
Congenital hypothyroidism is a preventable cause of intellectual disability that requires immediate treatment with levothyroxine (L-T4) 10–15 mcg/kg/day. Treatment must not be delayed for further investigations such as thyroid scan, as early initiation (ideally within 2 weeks of birth) is critical for normal neurodevelopmental outcomes. Thyroid scan and ultrasound can be performed after treatment has been started without compromising the investigation.
Reference: Ghai Essential Pediatrics, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.