Gaxilose is a synthetic disaccharide that is hydrolyzed in the intestine by the lactase enzyme. Gaxilose is used to diagnose hypolactasia via presence of D-xylose after cleavage by lactase. The Spanish company VenterPharma was issued with marketing authorisation by the Spanish and German regulatory agencies for LacTEST. Diagnosis drug LacTEST® represents a noninvasive method based on oral administration of 4-galactosil-xilose (4-O-β-D galactopiranosil-D-xilose) whose INN is Gaxilose, for hypolactasia diagnosis. This synthetic disaccharide, a substrate of intestinal lactase is hydrolyzed and the result is 2 physiological products: galactose and xylose. Galactose is converted into glucose in the liver and xylose is absorbed from a passive way and partially metabolized endogenously (50%). The rest appears in blood and it is excreted finally through urine. The amount of xylose in urine is proportional to the activity of intestinal lactase. This represents a direct measure of hypo or normo lactasia.