Differential Diagnosis for a 4-Month-Old Boy with Pallor and Lethargy
- Single Most Likely Diagnosis
- Hemoglobinopathy (e.g., Hemoglobin S or C disease, or other abnormal hemoglobins): The presence of an extra band representing gamma tetramers on hemoglobin electrophoresis in the newborn screen suggests an underlying hemoglobinopathy. The patient's symptoms of pallor, lethargy, and mild scleral icterus are consistent with anemia, which can be a complication of hemoglobinopathies.
- Other Likely Diagnoses
- Iron deficiency anemia: Although the patient is exclusively breastfed, iron deficiency anemia can still occur, especially if the mother's diet is low in iron. The patient's symptoms of pallor and lethargy are consistent with anemia.
- Breast milk jaundice or other causes of neonatal jaundice: The patient's mild scleral icterus could be related to breast milk jaundice or other causes of neonatal jaundice, although the patient's age and lack of other symptoms make this less likely.
- Do Not Miss Diagnoses
- Sepsis or infection: Although the patient has good urine output and normal vital signs, sepsis or infection can present with non-specific symptoms such as lethargy and pallor. It is essential to consider this diagnosis to avoid missing a potentially life-threatening condition.
- Congenital adrenal hyperplasia: This condition can cause anemia, lethargy, and other symptoms, especially in males. Although the patient's newborn screen did not indicate this condition, it is essential to consider it due to the potential for severe consequences if missed.
- Rare Diagnoses
- Congenital dyserythropoietic anemia: This is a rare group of disorders characterized by anemia and abnormal erythropoiesis. The patient's symptoms and hemoglobin electrophoresis results could be consistent with this diagnosis, although it is less likely.
- Other rare hemoglobinopathies or red blood cell disorders: There are many rare hemoglobinopathies and red blood cell disorders that could cause the patient's symptoms. Although these are unlikely, they should be considered if other diagnoses are ruled out.