How is lactose intolerance diagnosed?

There are a number of different tests that can be used to determine whether lactose intolerance is present:

H2 breath test

In the H2 breath test, the test person first drinks a solution containing lactose. The hydrogen content in the exhaled air is then measured at fixed intervals. If the lactose cannot be broken down by the enzyme lactase, intestinal bacteria take over this process and produce hydrogen, among other things. A high hydrogen content in the exhaled air therefore indicates a low lactose tolerance.

Lactose load test

The lactose load test is often carried out in combination with the H2 breath test. The person concerned drinks a solution containing lactose. The doctor then checks how high the blood sugar level rises. With normal lactose utilization, the blood sugar level rises significantly. However, if the enzyme lactase is missing, less glucose enters the blood, so that the blood sugar level either remains constant or only rises slightly.

Genetic test

Genetic analysis is one of the simplest and most convenient methods for detecting lactase deficiency. The pharmacist uses a special cotton swab to take a sample of the oral mucosa, which is then analyzed in a certified laboratory. The result is usually available after a short time – and often the long search for the cause of the digestive problems is over. Another advantage of this procedure is that it is gentle: in contrast to the H2 breath test, the patient does not have to drink a solution containing lactose and is therefore spared any unpleasant side effects.