Lactose tolerance test measure the ability of your intestines to break down a type of sugar called lactose. This sugar is found in milk and other dairy products. If your body cannot break down this sugar, you are said to have lactose intolerance. This can cause gassiness, abdominal pain, cramps, and diarrhea.
Normally the body is able to process milk and other dairy products. Thanks to an enzyme in the intestines called lactase, which breaks lactose down during digestion. However, some people have levels of lactase that are lower than normal. For these people, instead of breaking down the milk sugar (lactose), the lactose will persist in the intestines and ferment. This inability to digest lactose is referred to as lactose intolerance.
Conducting a lactose intolerance test requires you to drink a liquid with lactose. After two hours, your doctor will take a blood sample to measure how much glucose is in your blood. If your blood glucose level does not rise, this means that your body is not digesting or absorbing lactose.
There are also other kinds of tests that can be used to check lactose intolerance. A Hydrogen Breath Test is another very common way to test for lactose intolerance. During this test, your doctor will instruct you to drink a liquid solution containing lactose. He will then have you breathe into a balloon-like instrument at set intervals to determine how much hydrogen there is in your breath. The more hydrogen you exhale, the more likely it is that your body is unable to process lactose. Doctors can also use a Stool Acidity Test to check for lactose intolerance, usually in infants or small children, as they are not eligible for other tests. A physician will take a stool sample to see if lactose is breaking down properly in their system. Fermenting lactose in the intestines (a sign of lactose intolerance) creates lactic acid, which can be detected in stool.