Also known as: galactokinase deficiency screening, GALK screening.

What is galactokinase?

Galactokinase is a common enzyme in the body that facilitates the metabolism of the sugar galactose found in dairy and some fruits and vegetables. When the body is deficient in galactokinase (a recessively inherited genetic disorder) it causes galactose and galactitol to build up in the body. Galactokinase is one of 3 inborn inherited errors of metabolism that lead to high blood levels of galactose (and one type of a group of disorders called galactosemia). In the newborn baby it presents primarily with the early onset of bilateral eye cataracts as a result of galactitol accumulating in the lens of the eye. The newborn blood screening test examines for the blood level of galactokinase which usually will identify a deficiency.

What happens during the procedure?

Blood is drawn either by routine heel prick or from a vein after birth as part of the newborn screening for inborn errors of metabolism (or later as appropriate) which is sent to a laboratory for testing.

Is any special preparation needed? 

In most cases, no special preparation is needed for the test.

What are the risk factors?

Pain, bleeding, infection and damage to surrounding organs and tissues (depending on how blood is drawn) are potential risks.

Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: March 26, 2019 12:25 PM