A 3-day-old boy is brought to the emergency department for evaluation of vomiting and abnormal movements. The patient's arms and legs began rhythmically jerking about 20 minutes ago. The movements were symmetric and lasted for a minute. He has also had persistent vomiting today, especially after feeding, and had an episode of loose, nonbloody stool. The patient was born at term after an uncomplicated pregnancy and is exclusively breastfed. Temperature is 37.1 C (98.8 F). Examination shows a lethargic newborn with diffuse hypotonia as well as jaundice. The liver edge is palpable. Laboratory results are as follows: Which of the following is the most likely diagnosis in this patient?

Question

A 3-day-old boy is brought to the emergency department for evaluation of vomiting and abnormal movements.  The patient's arms and legs began rhythmically jerking about 20 minutes ago.  The movements were symmetric and lasted for a minute.  He has also had persistent vomiting today, especially after feeding, and had an episode of loose, nonbloody stool.  The patient was born at term after an uncomplicated pregnancy and is exclusively breastfed.  Temperature is 37.1 C (98.8 F).  Examination shows a lethargic newborn with diffuse hypotonia as well as jaundice.  The liver edge is palpable.  Laboratory results are as follows:  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

11ec25c8_d6ec_c1ff_bc81_f9e0bd74c6cf_MD0003_00 Galactosemia is a metabolic disorder most commonly caused by galactose-1-phosphate uridylyltransferase (GALT) deficiency. In affected newborns, galactose (found in breast milk and standard cow's milk-based formula) cannot be reduced to glucose. This dysfunction leads to elevated serum galactose-1-phosphate, galactose accumulation in tissues (eg, liver, kidneys), and hypoglycemia. reduced Therefore, galactosemia typically presents in the first few days of life after the ingestion of galactose or its precursor lactose. Affected newborns develop jaundice and conjugated hyperbilirubinemia due to liver disease; some also have unconjugated hyperbilirubinemia due to hemolysis. Seizure caused by severe hypoglycemia may be the presenting symptom, as in this patient. Vomiting and failure to gain weight are also common, and examination often reveals hepatomegaly (due to galactose accumulation), lethargy, and hypotonia. Galactosemia can be identified on routine newborn screening; however, these results are usually not available in the first week of life. Supportive laboratory findings on presentation include nonglucose urine reducing substances suggestive of galactosuria. Absent GALT activity in red blood cells confirms the diagnosis. Treatment is dietary elimination of galactose via the use of soy-based formula. With treatment, end-organ dysfunction typically resolves, and the prognosis is good. (Choice A) Biliary atresia, characterized by progressive fibrosis and obliteration of the extrahepatic bile ducts, typically presents at age 2-8 weeks with failure to thrive, hepatomegaly, and conjugated hyperbilirubinemia. Vomiting, hypotonia, and nonglucose urine reducing substances would not be seen. (Choice B) Breastfeeding failure jaundice, a common and generally benign condition in the first week of life, presents with weight loss and unconjugated hyperbilirubinemia. Vomiting and direct hyperbilirubinemia would not be expected. (Choice D) Glycogen storage diseases can present with hepatomegaly and signs of hypoglycemia (eg, seizures). However, hypoglycemic episodes do not typically occur until age 3-6 months because they are caused by periods of fasting, which begin when the infant sleeps longer through the night. Glycogen storage diseases (Choice E) Urea cycle defects can present with lethargy and vomiting in newborns after the introduction of protein via breast milk or formula. However, an elevated ammonia level, a finding not seen in this patient, is characteristic. Educational objective: Galactosemia is a metabolic disorder in which deficient galactose-1-phosphate uridylyltransferase prevents the reduction of galactose to glucose. The disorder typically presents with jaundice, vomiting, hepatomegaly, and possibly seizures (due to hypoglycemia) in the first few days of life. The diagnosis is supported by the presence of nonglucose reducing substances in urine, which suggests galactosuria. References: Literature review and outcome of classic galactosemia diagnosed in the neonatal period. (http://www.ncbi.nlm.nih.gov/pubmed/24273939) Hereditary galactosemia. (http://www.ncbi.nlm.nih.gov/pubmed/29409891)

A 3-Day-Old Boy Is Brought to the Emergency Department for Evaluation