Differential Diagnosis for a 3-day-old Boy with Vomiting and Abnormal Movements
- Single Most Likely Diagnosis
- Galactosemia: This condition is suggested by the presence of reducing substances in the urine (indicative of galactose), persistent vomiting after feeding (especially with lactose-containing breast milk or formula), lethargy, diffuse hypotonia, and jaundice. The liver edge being palpable also supports this diagnosis, as galactosemia can lead to hepatomegaly.
- Other Likely Diagnoses
- Hereditary Fructose Intolerance: Although less likely given the early presentation and the fact that fructose is not typically introduced this early, it could be considered if the infant had been exposed to fructose. Symptoms can include vomiting, lethargy, and hypoglycemia after ingestion of fructose.
- Congenital Infections (e.g., Sepsis): The presence of vomiting, lethargy, and jaundice could also suggest a congenital infection. However, the absence of fever and specific laboratory findings (like elevated white blood cell count) makes this less likely.
- Do Not Miss Diagnoses
- Hypoxic-Ischemic Encephalopathy: Although the history does not specifically suggest a hypoxic-ischemic event, the presence of seizures (rhythmic jerking) and lethargy necessitates considering this diagnosis due to its potential for severe neurological consequences.
- Inborn Errors of Metabolism (e.g., Maple Syrup Urine Disease, Organic Acidemias): These conditions can present with nonspecific symptoms such as vomiting, lethargy, and hypotonia. The slightly elevated ammonia level, although within normal limits, should prompt consideration of these diagnoses due to their potential severity.
- Congenital Adrenal Hyperplasia: This condition can lead to hypoglycemia, vomiting, and lethargy, especially in salt-wasting forms. It's crucial to consider due to the potential for adrenal crisis.
- Rare Diagnoses
- Pyridoxine-Dependent Epilepsy: This rare condition presents with seizures that are resistant to conventional antiepileptic drugs but respond to pyridoxine (vitamin B6). The rhythmic jerking movements could be seizures, making this a consideration, albeit rare.
- Glycogen Storage Diseases: These diseases can lead to hypoglycemia and hepatomegaly but are less likely given the early presentation and specific pattern of symptoms.
- Methylmalonic Acidemia: An inborn error of metabolism that can present with vomiting, lethargy, and hypotonia due to metabolic acidosis and hyperammonemia. It's a rare condition but should be considered in the differential due to its severity.