The disease is detected by measuring the level of enzyme in red blood cells, white blood cells or liver. A galactose tolerance test should never be done, as it may be harmful. Affected infants who ingest galactose will excrete it in large quantities in their urine where it can also be detected. If the infant is vomiting, and not taking milk, the test can be negative. If the disease is suspected, the diagnosis should be confirmed by blood testing.
Treatment is based on the elimination of galactose from the diet.
This diet should be compulsively followed, and continued for years, and possibly for life. It is also recommended that mothers of affected infants by placed on a galactose-free diet during subsequent pregnancies. This may somewhat modify symptoms present at birth. With early therapy, any liver damage which occurred in the first few days of life will nearly completely heal. Galactosemia should be considered in any jaundiced infant because of beneficial effects of early dietary restricting.