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Difficulty: EasyPediatric Genetic and Metabolic Disorders

A 12-day-old male infant is brought to the emergency department by his parents due to excessive vomiting, poor feeding, and lethargy over the past two days. He was born at term without complications and has been exclusively breastfed since birth. Physical examination reveals scleral icterus, diffuse jaundice, and a palpable liver edge 3 cm below the right costal margin. Ophthalmologic examination is notable for bilateral cataracts. Laboratory testing demonstrates hypoglycemia and elevated liver transaminases. Which of the following is the most appropriate next step in the management of this patient's condition?

  1. Switch feeds to a soy-based infant formulaAnswer
  2. B
    Transition to a phenylalanine-restricted diet
  3. C
    Eliminate fruit juices and purees from the diet
  4. D
    Initiate frequent feedings with uncooked cornstarch
  5. E
    Admit for intensive phototherapy and continue breastfeeding

Answer

Switch feeds to a soy-based infant formula
This infant's presentation of jaundice, hepatomegaly, bilateral cataracts, and hypoglycemia following the ingestion of breast milk is highly characteristic of classic galactosemia. This autosomal recessive disorder is caused by a deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT). Breast milk and standard infant formulas contain lactose, a disaccharide that is broken down into glucose and galactose. The inability to further metabolize galactose leads to an accumulation of galactose-1-phosphate, which is toxic to the liver (causing jaundice, transaminitis, and hepatomegaly) and kidneys. Additionally, excess galactose is converted by aldose reductase into galactitol, which accumulates in the lenses of the eyes and causes cataracts. The most appropriate initial management is to immediately discontinue all lactose-containing feeds (including breast milk) and switch to a soy-based formula, which is lactose-free. Prompt dietary modification is crucial to prevent life-threatening complications, including Escherichia coli sepsis.

Step-by-Step Solution

1
Analyze the clinical presentation and feeding history.
The patient is a neonate with jaundice, hepatomegaly, bilateral cataracts, and hypoglycemia who is exclusively breastfed.
Identifying the onset of symptoms associated with breast milk consumption (which contains high amounts of lactose) points toward a specific metabolic block.
2
Identify the underlying metabolic disorder.
The triad of infantile cataracts, liver dysfunction (hepatomegaly, jaundice, elevated transaminases), and feeding intolerance on a lactose-containing diet is the classic presentation of galactosemia.
Classic galactosemia is caused by a severe deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT).
3
Determine the appropriate management.
The correct management is the immediate dietary restriction of all lactose and galactose.
Soy-based infant formulas contain sucrose or corn syrup instead of lactose, making them safe and therapeutic for infants with galactosemia.

Key Concept

Diagnosis and management of classic galactosemia
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Topics

Pediatric Genetic and Metabolic Disorders

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