How to Test for Lactose Tolerance

Lactose intolerance is the inability to digest the milk sugar in dairy products. Symptoms range from abdominal discomfort with gas and bloating to cramps and diarrhea. If you are lactose intolerant, you lack the lactase enzyme, which breaks down the glucose and galactose in milk sugar. Aging, ethnicity and premature birth can contribute to lactose intolerance. It can also be a secondary condition that develops later in life, as a result of illness, injury or abdominal radiation.

Instructions

• 1

  Keep a food log to determine if dairy foods upset your stomach.

  Start a symptom diary. Consistent gastric problems 30 minutes to two hours after eating a meal that includes dairy products is a significant clue to possible lactose intolerance. Jot down your meal choices and your symptoms for a few weeks to see if there is a correlation between eating pizza with extra cheese or fettuccine alfredo and subsequent abdominal discomfort.

• 2

  Oranges or fortified juices can help provide the calcium your body needs.

  Reduce dairy products. If your symptom diary does reflect an increase in gassiness, bloating or diarrhea after eating milk products, consciously reduce your dairy intake. Do your symptoms improve or disappear? If so, it's likely you have some degree of lactose intolerance.

• 3

  Be prepared to answer your doctor's questions about diet and medical history.

  See your doctor. If you believe you may be lactose intolerant, your doctor can confirm it with a few simple lab tests. Take your symptom diary and a complete list of any medications you take to your appointment.

• 4

  Take a hydrogen breath test. This test requires that you fast and limit your activity for eight hours beforehand. Lactose-intolerant individuals emit more hydrogen when breathing because the undigested lactose ferments in the colon, giving off extra hydrogen. For this test, you will first breathe into a balloon-like container and the hydrogen level will be noted. Additional breath samples will be recorded at intervals after you drink a liquid high in lactose. The higher the hydrogen level, the more likely that you are lactose intolerant.

• 5

  Blood glucose that rises less than 20 mg/dL is an abnormal result.

  Take a blood test. A lactose-intolerance blood test involves taking a blood sample before drinking a high-lactose liquid and additional blood samples up to two hours after you finish the drink. If the amount of glucose in your blood does not increase, that is a sign your body is not digesting lactose.Fasting and limited activity also are required for eight hours before this test.

• 6

  Young children may need soy or rice milk to manage lactose intolerance.

  Schedule a stool acidity test. This is a good option for babies or young children because it can be harmful for them to ingest the high-lactose liquids necessary for the other two tests. Lactic acid forms when undigested lactose ferments in the colon, and this can be determined by testing a stool sample.