Lactose tolerance tests

Two common methods include: Lactose tolerance blood test Hydrogen breath test The hydrogen breath test is the preferred method. It measures the amount of hydrogen in the air you breathe out. You will be asked to breathe into a balloon-type container. You will then drink a flavored liquid containing lactose. Samples of…

You should not eat or do heavy exercise for 8 hours before the test.

There should not be any pain or discomfort when giving a breath sample. When the needle is inserted to draw blood, some people feel slight pain, while others feel only a prick or stinging feeling. Afterward, there may be some throbbing.

Your health care provider may order these tests if you have signs of lactose intolerance.

The breath test is considered normal if the increase in hydrogen is less than 20 parts per million (ppm) over your fasting (pre-test) level. The blood test is considered normal if your glucose level rises more than 30 mg/dL (1.6 mmol/L) within 2 hours of drinking the lactose solution. A rise of 20 to 30 mg/dL (1.1 to…

Abnormal results may be a sign of lactose intolerance. A breath test result that shows a rise in hydrogen content of 20 ppm over your pre-test level is considered a positive test. This means you may have trouble breaking down lactose. The blood test is considered abnormal if your glucose level rises less than 20 mg/dL…

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others. Other risks associated with having blood drawn are slight, but may include: Fainting…

Floch MH. Lactose, fructose, and sucrose intolerance. In: Floch MH, ed. Netter's Gastroenterology . 3rd ed. Philadelphia, PA: Elsevier; 2020:chap 63. Höegenauer C, Hammer HF. Maldigestion and malabsorption. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease . 11th…