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Galactosemia Tests
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Galactosemia Tests

Galactosemia tests are blood screenings performed on newborns to detect a rare genetic disorder that prevents the body from breaking down the sugar galactose.

Overview

Galactosemia is a rare genetic metabolic disorder. Metabolism is the process the body uses to convert food into energy. Infants with galactosemia cannot break down galactose, a simple sugar found in breast milk, dairy products, and some fruits and vegetables. The condition is inherited, requiring the baby to receive the gene from both parents.

The disorder is categorized by the specific enzyme deficiency involved:

  • GALT (galactose-1 phosphate uridyl transferase) deficiency: Also known as classic galactosemia; the most common and severe form.
  • GALK (galactose kinase) deficiency.
  • GALE (galactose epimerase) deficiency.

If untreated, galactose accumulates in the blood, leading to liver disease, kidney failure, brain damage, or death. Early diagnosis allows for effective dietary management.

Why does my baby need a test?

In the United States, this test is a mandatory part of newborn screening. Older infants may be tested if they exhibit symptoms such as vomiting, poor weight gain, refusal to eat, irritability, or jaundice (yellowing of the skin and eyes).

What happens during the test?

A health care provider cleans the baby's heel and uses a small needle to poke the skin. A few drops of blood are collected, and a bandage is applied to the site. There are no special preparations required for this test.

Risks

The baby may feel a brief pinch during the heel poke, and a small bruise may form at the site, which typically resolves quickly.

What do the results mean?

  • Negative: The child does not have the disorder.
  • Positive: The baby will require follow-up testing, such as additional blood, urine, or genetic tests, to confirm the diagnosis.

Management

There is no cure for galactosemia, but it is managed through diet. Infants are fed soy formula or other lactose-free alternatives. Children with classic galactosemia must strictly avoid all milk and milk-containing products for life and may require calcium supplements. Those with GALK or GALE deficiencies may be able to include limited amounts of dairy in their diet, as determined by their health care provider.

Frequently Asked Questions

Children with galactosemia require lifelong monitoring by a metabolic specialist. This typically includes regular blood tests to check liver and kidney function, eye exams to screen for cataracts, and developmental assessments. The frequency of visits may decrease as the child grows, but annual check-ups are standard to ensure the diet is effective and to manage any emerging complications.
No, a positive newborn screening is a preliminary result that requires confirmation. False positives can occur due to technical issues or other metabolic conditions. Your provider will order specific enzyme activity tests or genetic testing to confirm the diagnosis. Until confirmed, you should consult your pediatrician about whether to temporarily switch to a soy-based formula, but do not stop breastfeeding without medical guidance unless directed by a specialist.
Untreated galactosemia leads to the accumulation of toxic galactose metabolites, which can cause severe liver damage, kidney failure, cataracts, and significant neurological impairment. In classic galactosemia, it can be fatal in infancy. Even with strict dietary management, some individuals may experience long-term complications such as speech difficulties, learning disabilities, or ovarian insufficiency in females, which require ongoing monitoring by a metabolic specialist.
No. Breast milk contains lactose, which breaks down into glucose and galactose. Since the baby cannot process galactose, breastfeeding is contraindicated. You must switch to a galactose-free formula, typically soy-based. It is important to pump and discard breast milk to maintain supply if you plan to return to work, but the milk must not be given to the baby.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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