Lactose Tolerance Tests
Reviewed
Lactose tolerance tests measure your body's ability to break down lactose. There are two types: a hydrogen breath test that measures hydrogen gas in your breath, and a glucose blood test that measures blood glucose levels after drinking a lactose-containing liquid.
Preparation and collection
Fast (not eat or drink) for eight to 12 hours before the test. Stop taking antibiotics for two to four weeks before the test. Do not smoke or exercise strenuously the day before the test. You may also need to stop taking certain medicines, such as laxatives, antacids, and stool softeners; tell your provider about everything you take and do not stop any medicines unless your provider tells you to. If you are having a breath test, you may need to brush your teeth or rinse your mouth shortly before the test.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- If you are lactose intolerant, you may feel cramps or bloating after drinking the lactose beverage. The supplied source states there are no other risks to having a hydrogen breath test. There is very little risk to having a blood test; there may be slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
- A negative result does not completely rule out lactose intolerance; further testing may be needed.
What to do next
If you are diagnosed with lactose intolerance, you should be able to manage your condition by limiting or avoiding foods with lactose, such as milk and cheese. Some people with lactose intolerance can have a limited amount of dairy without symptoms. Other people may need to avoid lactose altogether. Taking a supplement that contains lactase may also help manage your condition. Be sure to talk to your provider about planning your diet and/or taking lactase supplements.