DBS Total Galctose, >1 Mth

What is the Total Galactose test and why is it done at 1 month of age?

The Total Galactose (TGal) test measures the level of galactose and galactose-1-phosphate in the blood. It is mainly used to screen for galactosemia, a rare but serious genetic disorder in which the body cannot properly process galactose, a sugar found in milk and dairy products. Performing the test around one month of age ensures early detection and prompt dietary management to prevent life-threatening complications.


How is this test performed?

A small blood sample is collected via heel prick or venipuncture and analyzed using enzymatic or fluorometric assays to quantify galactose levels. The test checks for both free galactose and its phosphate derivative, which can accumulate to toxic levels in individuals with galactosemia.


What do abnormal results mean?

Elevated levels of total galactose may indicate classic galactosemia or one of its variants, such as galactokinase deficiency. These conditions, if untreated, can cause severe complications including liver damage, kidney failure, intellectual disability, and even death. A positive result usually prompts confirmatory testing, including enzyme assays and genetic testing, to pinpoint the exact cause.


Is this test part of routine newborn screening?

 In many regions, galactosemia screening is part of standard newborn screening panels. However, if initial testing is missed or inconclusive, the TGal test may be repeated at 1 month of age, especially if the baby shows symptoms like vomiting, jaundice, lethargy, or failure to thrive.


Does the baby need to fast or stop milk before this test?

No special preparation is required, but the test is most informative when the infant is consuming milk, as this ensures galactose is present in the diet. Stopping milk beforehand may lead to false-negative results.