Galactosemia

Background

• Galactosemia is an autosomal recessive disorder of galactose metabolism, most commonly caused by deficiency of galactose-1-phosphate uridylyltransferase (GALT), resulting in toxic accumulation of galactose-1-phosphate and galactitol in the liver, brain, kidneys, and lens. Classic galactosemia is a neonatal emergency — affected infants become critically ill within the first week of life after ingesting breast milk or lactose-containing formula, presenting with liver failure, E. coli sepsis, coagulopathy, and cataracts. The disease is rapidly reversible with lactose elimination from the diet but fatal if unrecognized.
• The emergency physician must consider galactosemia in any neonate with E. coli sepsis, any infant with liver failure and feeding difficulties, and any infant with cataracts.
• Autosomal recessive; incidence approximately 1 in 16,000-60,000 live births depending on population
• Three enzyme deficiencies cause galactosemia; GALT deficiency (classic galactosemia) is the most severe and EM-relevant:

Type	Enzyme deficiency	Key features
Classic galactosemia	GALT (galactose-1-phosphate uridylyltransferase)	Life-threatening; liver failure, E. coli sepsis, cataracts, brain damage; this page's focus
Galactokinase (GALK) deficiency	GALK	Cataracts only; no liver or brain disease; much milder
Epimerase (GALE) deficiency	GALE	Usually benign (RBC-confined); rare generalized form resembles classic galactosemia

Mechanism

• Lactose (in breast milk and cow's milk formula) is digested to glucose + galactose in the intestine
• Galactose is normally metabolized by the Leloir pathway: galactose → (GALK) → galactose-1-phosphate → (GALT) → UDP-galactose → UDP-glucose
• In GALT deficiency: galactose-1-phosphate (Gal-1-P) accumulates → direct toxicity to hepatocytes, renal tubular cells, and neurons
• Galactose is shunted to alternative pathways → galactitol (a sugar alcohol) accumulates in the lens → osmotic swelling of lens fibers → cataracts
• ATP depletion occurs in hepatocytes from phosphate trapping (analogous to Hereditary fructose intolerance)
• Impaired neutrophil function from galactose metabolite accumulation → predisposition to gram-negative sepsis, especially E. coli

The E. coli sepsis connection

• Approximately 10% of neonates with classic galactosemia develop E. coli sepsis; E. coli accounts for ~76% of sepsis episodes in galactosemia
• The sepsis may precede or occur simultaneously with the diagnosis of galactosemia
• Any term neonate with E. coli sepsis should be evaluated for galactosemia — this is one of the most important EM teaching points

Clinical features

Classic presentation (first week of life)

• Previously well newborn begins breast milk or cow's milk formula feedings
• Symptoms appear within days of starting milk feedings
• Feeding difficulties: poor sucking, vomiting, diarrhea
• Lethargy, hypotonia, irritability
• Jaundice (may be conjugated or unconjugated; often both)
• Hepatomegaly (may progress rapidly)
• Coagulopathy (elevated PT/INR — hepatic synthetic failure; excessive bleeding from venipuncture sites is a characteristic early sign)
• Ascites (may appear within first few days of life)
• Hypoglycemia
• Cataracts (bilateral "oil drop" cataracts; may not be visible to the naked eye — slit-lamp examination required; may develop as early as 1-2 weeks of age)
• Renal tubular dysfunction (Fanconi syndrome: glycosuria, aminoaciduria, phosphaturia)
• Sepsis — especially E. coli; may be the presenting feature before liver failure is apparent
• Seizures, cerebral edema (in severe/untreated cases)
• Death — if unrecognized; typically from sepsis, liver failure, or bleeding

Diagnostic clues

• Symptoms temporally related to milk feedings (breast milk or standard formula — both contain lactose)
• Contrast with Hereditary fructose intolerance: galactosemia presents in the first days of life (because all neonates receive milk); HFI presents at 4-6 months (when weaning foods introduce fructose)
• E. coli sepsis in a term neonate (term neonates with sepsis are less common than in preterms; E. coli is the most common pathogen in galactosemia-associated sepsis)
• Reducing substances positive in urine (galactose is a reducing sugar) — classic bedside clue, though nonspecific and with false negatives

Long-term complications (even with early treatment)

• Cognitive impairment, learning disabilities
• Speech and language deficits (childhood apraxia of speech)
• Extrapyramidal movement disorders (tremor, ataxia, dystonia)
• Premature ovarian insufficiency in females (occurs despite dietary treatment)
• Osteoporosis
• These complications are thought to result from endogenous galactose production and possibly prenatal toxicity — they cannot be fully prevented by postnatal dietary restriction

Differential diagnosis

Neonate with liver failure, sepsis, and jaundice

• Galactosemia (milk-related; E. coli sepsis; cataracts; reducing substances in urine)
• Hereditary fructose intolerance (fructose-related; later onset at 4-6 months; no cataracts)
• Tyrosinemia type 1 (very high AFP + coagulopathy out of proportion to transaminases; Fanconi syndrome; not food-specific)
• Neonatal HSV (disseminated; vesicular rash; markedly elevated ALT)
• Bacterial sepsis (other organisms; no cataracts; normal reducing substances)
• Neonatal hemochromatosis (GALD; iron overload; presents at birth, before feeding)
• Neonatal hepatitis (other causes)
• Biliary atresia (conjugated hyperbilirubinemia; acholic stools; no acute liver failure early)
• Hemophagocytic lymphohistiocytosis (HLH)

The galactosemia-HFI comparison (high-yield EM distinction)

Feature	Galactosemia	Hereditary fructose intolerance
Offending sugar	Galactose (from lactose in milk)	Fructose (from fruits, sucrose, sorbitol)
Typical onset	First days of life (milk feedings start at birth)	4-6 months (when weaning foods introduce fructose)
Cataracts	Yes (oil drop; slit-lamp)	No
E. coli sepsis	Yes (~10%; characteristic)	No
Reducing substances in urine	Positive (galactose)	May be positive (fructose)
Fanconi syndrome	Yes	Yes
Glucagon response	Partially effective	Not effective (dual glycogenolysis/gluconeogenesis block)
Treatment	Remove lactose (use soy formula)	Remove fructose/sucrose/sorbitol

Evaluation

ED workup

• Blood glucose: hypoglycemia (common)
• Hepatic panel: elevated AST/ALT (hepatocellular injury); elevated bilirubin (conjugated, unconjugated, or both)
• Coagulation studies: elevated PT/INR (often markedly — hepatic synthetic failure)
• CBC: evaluate for infection (leukocytosis or leukopenia with left shift in sepsis)
• Blood cultures: always obtain; high suspicion for E. coli
• Urinalysis: reducing substances — positive if galactose present; this is NOT the same as a glucose dipstick (standard urine dipsticks detect glucose only, not galactose; Clinitest tablet or similar reducing substance test is needed)
  • Caveat: reducing substances may be negative if infant has been NPO or on IV fluids (no galactose intake); a negative result does not exclude galactosemia
• BMP: metabolic acidosis, electrolyte abnormalities, renal dysfunction
• Ammonia: may be elevated in severe hepatic failure
• Lactate: elevated (hepatic failure, tissue hypoperfusion)
• Albumin: low (hepatic synthetic failure)
• Ophthalmologic examination: slit-lamp for oil drop cataracts (may not be visible without slit-lamp in the first weeks)

Newborn screening

• Galactosemia is included in newborn screening (NBS) panels in most countries
• NBS measures GALT enzyme activity and/or blood galactose levels from dried blood spots
• NBS results may not be available before the infant becomes symptomatic — classic galactosemia presents in the first week of life, and NBS results may take days to return
• Do NOT wait for NBS results if galactosemia is clinically suspected — stop lactose immediately
• False negatives on NBS: may occur if infant has not yet received milk feedings, has received blood transfusion (donor RBCs have normal GALT activity), or sample was exposed to heat/humidity

Confirmatory testing (arrange via specialist)

• Erythrocyte GALT enzyme activity: absent or markedly reduced in classic galactosemia
• Erythrocyte galactose-1-phosphate level: elevated
• GALT gene sequencing: identifies specific mutations (Q188R is the most common severe mutation in Caucasians; S135L in African-descent populations — associated with milder disease)

Management

Immediate ED management

• STOP ALL LACTOSE-CONTAINING FEEDS IMMEDIATELY — this is the single most critical intervention
  • Stop breast milk
  • Stop all cow's milk-based formulas
  • Switch to soy-based formula (lactose-free) or casein hydrolysate formula
  • Do NOT wait for confirmatory testing — if galactosemia is suspected clinically, remove lactose immediately; this action is lifesaving and harmless if the diagnosis is wrong
• Empiric broad-spectrum antibiotics — ampicillin + gentamicin (or cefotaxime) per neonatal sepsis protocol; high suspicion for E. coli
• IV dextrose (D10W): correct and prevent hypoglycemia
• Correct coagulopathy: vitamin K (1 mg IM); FFP if active bleeding or severely prolonged INR
• IV fluids: dextrose-containing crystalloid; avoid lactated Ringer's (contains lactate, not lactose — technically safe, but dextrose-containing NS is preferred for clarity)
• Supportive care for liver failure: manage per Acute liver failure protocols
• Monitor: blood glucose frequently, coagulation studies, bilirubin, hepatic panel, renal function

Medication safety

• Check all oral medications for lactose and galactose as excipients — many tablets use lactose as a filler
• Use IV formulations when possible during the acute phase
• Consult pharmacy to verify medication safety

Long-term management (arrange via metabolic specialist)

• Lifelong strict lactose-restricted diet — eliminates all dairy products, casein, and whey-containing foods
• Soy-based formula in infancy; careful dietary education throughout life
• Calcium and vitamin D supplementation (osteoporosis prevention — dairy restriction limits calcium intake)
• Regular monitoring of: erythrocyte Gal-1-P levels, cataracts, speech and development, ovarian function (in females), bone mineral density
• Life expectancy is normal with early diagnosis and dietary compliance; liver transplantation is NOT required (unlike tyrosinemia type 1)

Disposition

• All infants with suspected or confirmed galactosemia: admit
  • NICU if septic, liver failure, or coagulopathy
  • Stop all lactose-containing feeds
  • Empiric antibiotics pending cultures
  • Metabolic/genetics consultation
• Discharge criteria:
  • Feeding well on lactose-free formula
  • Blood glucose stable
  • Coagulopathy improving
  • Infection treated or excluded
  • Metabolic specialist follow-up arranged
  • Family educated on dietary restrictions
• Ensure the family understands:
  • No breast milk — this is emotionally difficult for mothers and requires sensitive counseling; explain that breast milk contains lactose which is harmful to the infant
  • No standard cow's milk formula
  • Careful reading of all food labels for lactose, galactose, casein, whey content
  • All medications must be checked for lactose excipients
  • Medical alert identification for the infant

See Also

• Hereditary fructose intolerance
• Tyrosinemia
• Neonatal hepatitis
• Fanconi syndrome
• Neonatal sepsis
• Acute liver failure
• Neonatal hemochromatosis
• Cataracts

External Links

• GeneReviews — Classic Galactosemia and Clinical Variant Galactosemia
• StatPearls — Hereditary Fructose Intolerance (for comparison)
• Medscape — Galactosemia Clinical Presentation
• World J Clin Pediatr — Hereditary fructose intolerance: A comprehensive review (2022)
• Orphanet — Hereditary fructose intolerance