Differential Diagnosis for the 1-month-old Boy
The patient's presentation of scleral icterus, jaundice, large protruding tongue, hoarse cry, and laboratory results indicating elevated TSH and low T4 levels suggest a diagnosis of congenital hypothyroidism. Here is the differential diagnosis organized into categories:
- Single most likely diagnosis
- D. Thyroid dysgenesis: This is the most common cause of congenital hypothyroidism, accounting for approximately 80% of cases. The patient's symptoms and laboratory results are consistent with this diagnosis.
- Other Likely diagnoses
- A. Defective thyroid peroxidase activity: This is a possible cause of congenital hypothyroidism, although less common than thyroid dysgenesis. It is an autosomal recessive disorder that affects the production of thyroid hormones.
- E. Transplacental TSH receptor–stimulating antibody: This is a rare cause of congenital hypothyroidism, but it can occur in infants born to mothers with Graves' disease.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- C. Panhypopituitarism: Although less likely, panhypopituitarism can present with similar symptoms, including hypothyroidism, and is a life-threatening condition if left untreated.
- Rare diagnoses
- B. Iodine deficiency (endemic goiter): This is unlikely in this case, as the mother consumed a well-balanced diet and took prenatal vitamins throughout the pregnancy, suggesting adequate iodine intake. However, it is still a possible cause of congenital hypothyroidism in areas with endemic iodine deficiency.