If you are lactose intolerant, your small intestine cannot adequately produce an enzyme called lactase, which helps break down lactose. Because of this, you may experience nausea, bloating, diarrhea, gas and abdominal cramps after consuming foods that contain lactose. Lactose intolerance is a common condition, so many health care providers do not classify it as a disease. If you suspect that you are lactose intolerant, your doctor can perform a series of tests to properly diagnose the condition.
Lactose Tolerance Test
A lactose tolerance test involves drinking a liquid that contains high levels of lactose and monitoring the body's response to that liquid. If you are able to digest lactose properly, the sugar will travel through your digestive tract and then move into your bloodstream, causing your blood glucose levels to rise. Two hours after you consume the lactose drink, your blood will be taken and your glucose levels will be tested. If your glucose levels did not rise, it indicates that your body did not properly digest the lactose in the drink.
Hydrogen Breath Test
A hydrogen breath test also involves drinking a liquid that contains a large amount of lactose. After consuming the lactose drink, the hydrogen levels in your breath will be tested at regular intervals. Normally, your breath contains very small amounts of hydrogen. If you are lactose intolerant, lactose moves through your digestive system in its full form until it reaches the bacteria in the large intestine. The bacteria feed on the lactose and produce gases, including hydrogen, as a waste product. This hydrogen exits your body through your breath and is apparent on a breath test.
Stool Acidity Test
A stool acidity test is used for infants and children for which the other tests cannot be used. When your body cannot digest lactose properly, the undigested lactose ferments into lactic acid in the colon. Your body excretes this lactic acid in your stool. If lactose intolerance is suspected, the levels of lactic acid in the stool are tested.
Enteroscopy
An enteroscopy cannot directly diagnose lactose intolerance, but it may be used as a part of lactose intolerance testing to rule out the possibility that other more serious conditions may be causing your symptoms. The procedure involves inserting a thin tube, called an endoscope, into the nose or mouth and extending it into the gastrointestinal tract to view the inside of the small intestine. During the procedure, a small tissue sample will be removed in order to perform a biopsy. The biopsy can determine if you have a more serious digestive condition, such as Crohn's disease, or another underlying medical condition.
