Galactosemia Test
Reviewed
A galactosemia test is a blood test used in newborns to screen for a rare genetic metabolic disorder that prevents the body from breaking down galactose, a sugar found in milk, dairy, and some fruits and vegetables. The test is part of routine newborn screening in the United States. A positive screen requires follow-up testing to confirm the diagnosis and determine the specific enzyme deficiency. Early diagnosis and dietary management can prevent serious health problems such as liver disease, kidney failure, brain damage, or death. The test involves a heel prick and carries minimal physical risk.
Preparation and collection
No special preparation is needed.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- The heel prick may cause a brief pinch and a small bruise that resolves quickly.
- As a screening test, there is a risk of false-positive (suggesting a problem when none exists) and false-negative (missing a problem) results. Further testing is needed to confirm any positive screen due to the possibility of laboratory error or other factors.
What to do next
If the result is screen-negative, no immediate follow-up is needed, but report any symptoms (vomiting, poor weight gain, refusal to eat, irritability, jaundice) to your healthcare provider. If the result is screen-positive, your baby will need additional blood tests, urine tests, and genetic tests to confirm the diagnosis and determine the specific enzyme deficiency (GALT, GALK, or GALE). Early diagnosis and dietary management (e.g., soy formula, lactose-free formula, and lifelong avoidance of milk/dairy for classic galactosemia) can prevent serious health problems. There is no cure, and children with classic galactosemia require a special diet and calcium supplements. Those with GALK or GALE deficiencies may be able to include limited dairy. Discuss a safe diet and follow-up plan with your healthcare provider.