A 3-month-old infant presents with round face, large protruding tongue, dry skin, umbilical hernia, and constipation. The most likely diagnosis is?

• A. Hyperparathyroidism
• B. Nephrotic syndrome
• C. Phenylketonuria
• D. Hypothyroidism

Answer: (D)

Infant hypothyroidism present in early life typically shows a hypo-metabolic, edematous state with distinctive facial and systemic features. The round face and large protruding tongue reflect tissue enlargement from mucopolysaccharide deposition and generalized myxedema due to thyroid hormone deficiency. Dry skin and constipation stem from reduced skin turnover and slowed gut motility, while an umbilical hernia arises from weakened abdominal wall support and edema common in untreated thyroid hormone deficiency. Together, these signs—macroglossia, puffy face, dry skin, umbilical hernia, and constipation—are classic for congenital hypothyroidism in an infant. If not treated promptly, that hormone shortfall can lead to growth delay and intellectual impairment, which is why screening and early therapy are so crucial.