Clinical scenario: Persistent jaundice | slow baby
A 4-week-old term male infant is referred because of persistent jaundice. He has been exclusively breastfed since birth. His parents report that he feeds slowly, sleeps for prolonged periods, and has bowel movements only every 4–5 days. He was treated with phototherapy during the first week of life, but the jaundice has persisted. There is no history of fever, vomiting, or pale stools.
On examination, the infant appears sleepy but arousable. His heart rate is 88 beats/min, temperature is 35.9°C, and weight gain has been suboptimal. There is mild generalized hypotonia. No hepatosplenomegaly is detected.
Investigations reveal:
- Total bilirubin: 14.2 mg/dL (243 μmol/L)
- Direct bilirubin: 0.5 mg/dL (9 μmol/L)
- Hemoglobin: Normal
- Reticulocyte count: Normal
- Direct Coombs test: Negative
- Liver transaminases: Normal
Which of the following is the most likely diagnosis?
A. Breast milk jaundice
B. Congenital hypothyroidism
C. Crigler–Najjar syndrome type II
D. Gilbert syndrome
E. Glucose-6-phosphate dehydrogenase deficiency
Correct answer & Explanation:
Correct Answer
B. Congenital hypothyroidism
Explanation: Congenital hypothyriodism
This infant has persistent unconjugated hyperbilirubinemia with systemic features suggestive of hypothyroidism, although the classic signs are intentionally absent.
Important clues include:
- Persistent jaundice beyond 3 weeks
- Poor feeding
- Excessive sleepiness
- Constipation
- Bradycardia
- Hypothermia
- Poor weight gain
- Mild hypotonia
- No evidence of hemolysis
- Normal liver function tests
Congenital hypothyroidism reduces hepatic bilirubin conjugation and intestinal motility, resulting in persistent unconjugated hyperbilirubinemia. Confirmation requires elevated TSH with low free T4, and levothyroxine should be started promptly once the diagnosis is confirmed.
Why the other options are incorrect
A. Breast milk jaundice
- Usually affects a healthy, thriving infant.
- Does not cause bradycardia, hypothermia, constipation, hypotonia, or poor weight gain.
C. Crigler–Najjar syndrome type II
- Produces isolated unconjugated hyperbilirubinemia.
- The infant is otherwise clinically well and lacks features of systemic illness.
D. Gilbert syndrome
- Typically presents in older children or adolescents with mild intermittent unconjugated hyperbilirubinemia.
E. Glucose-6-phosphate dehydrogenase deficiency
- Causes hemolytic jaundice with reticulocytosis and other evidence of hemolysis, which are absent here.
Clinical Pearl
In a thriving infant, persistent unconjugated jaundice usually suggests breast milk jaundice. However, persistent jaundice accompanied by bradycardia, hypothermia, constipation, lethargy, or poor weight gain should prompt immediate evaluation for congenital hypothyroidism, even when the classic physical features (macroglossia, umbilical hernia, large fontanelle) are absent.
