Lactose intolerance test
Updated onMarian Grosser studied human medicine in Munich. In addition, the doctor, who was interested in many things, dared to make some exciting detours: studying philosophy and art history, working on the radio and, finally, also for a Netdoctor.
More about the experts All content is checked by medical journalists.A lactose intolerance test is the only method to reliably diagnose lactose intolerance. It cannot be clearly determined based on the symptoms alone. Other food intolerances and a number of illnesses express themselves with similar complaints. There are several ways to test someone for lactose intolerance. Read more about the various lactose intolerance test procedures here!
ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. E73
Why should you test for lactose intolerance?
Lactose intolerance (milk sugar intolerance) usually manifests itself in flatulence, abdominal pain, nausea and diarrhea if those affected have consumed too much milk sugar (lactose). the connection between lactose intake and occurrence of symptoms cannot always be clearly recognized.
However, it is important to know whether an intolerance to lactose is actually the cause of the symptoms. Then those affected will be able to design their diet in such a way that they have no or hardly any symptoms - by (largely) avoiding foods containing lactose such as milk and dairy products.
On the other hand, eating a lactose-free diet on the mere suspicion of being lactose-free is not a good idea: On the one hand, the lack of milk and dairy products also affects the supply of calcium - a mineral that is important for strong bones, among other things. On the other hand, buying "lactose-free" special products (such as lactose-free yoghurt, etc.) would put an unnecessary burden on your wallet.
So if you suspect that you cannot tolerate lactose, you should see a doctor and find out for yourself - with a test that can detect lactose intolerance with a high probability.
How do you test lactose intolerance?
There are various methods available to the doctor for the lactose intolerance test:
- Hydrogen breath test (H2 breath test)
- Lactose tolerance test (blood sugar test)
- Genetic test
- Small intestine biopsy
Finally, there is also the option of testing yourself for lactose intolerance (lactose intolerance self-test).
A positive test result alone (e.g. in the breath test) is not sufficient for a reliable diagnosis. According to the definition, lactose intolerance is only present if the person concerned also develops symptoms from taking lactose.
Hydrogen breath test
The most commonly used lactose intolerance test is the hydrogen breath test, also known as the H2 breath test. The hydrogen content in the exhaled air is measured before and after drinking a lactose solution. You can find out why the result allows conclusions to be drawn about lactose intolerance and what other intolerances can be detected with this method in the article H2 breath test.
Lactose tolerance test
You can also test for lactose intolerance using blood sugar levels. This method is an alternative if the hydrogen breath test does not help, but can also be used at the same time.
This is how the lactose tolerance test works
Normally, the double sugar lactose is broken down in the small intestine by the enzyme lactase into its two components - the single sugars glucose and galactose. These can then pass through the intestinal wall and enter the blood. In people who can tolerate lactose, the glucose level in the blood rises after ingesting lactose, which can be measured with any conventional blood sugar test.
In contrast, this test turns out negative in people with lactose intolerance - there is little or no increase in blood sugar levels because the lactose cannot or can hardly be broken down and absorbed in the intestine.
This is how the lactose tolerance test is carried out
Before starting the test As with the hydrogen breath test, the patient again takes a defined lactose solution. Before this and at certain time intervals for up to three hours afterwards, his blood sugar level is measured. Normally, milk sugar intake increases this by more than 20mg / dl. If this increase does not occur or if it is less, there is a lactose intolerance.
Another argument in favor of lactose intolerance is if the test person develops typical symptoms (abdominal pain, flatulence, diarrhea, etc.) after drinking the lactose solution.
Problems with the lactose tolerance test
This lactose intolerance test can be an alternative to the hydrogen breath test, but it is less precise and therefore not the method of first choice. In addition, the measured values in people with diabetes can be falsified.
Genetic test
If newborns react to breast milk or milk substitute food with symptoms such as diarrhea and vomiting, a congenital (neonatal) lactase deficiency could be the reason - a rare form of primary lactose intolerance (more on this under "Lactose intolerance: causes and triggers"). The suspicion can be confirmed with a genetic test.
Small intestine biopsy
In principle, it is also possible to take a tissue sample from the small intestine in order to measure the activity of the lactase present. In general, this is only done in the context of scientific research.
Lactose intolerance self-test
Some people who suspect that they cannot tolerate lactose carry out a diet / exposure test on their own: They avoid lactose-containing foods and drinks for a while to see whether their symptoms improve. If this is the case, it speaks for a lactose intolerance. In the next step, you can then drink a glass of lactose dissolved in water (available in drugstores and pharmacies) - that is, you can take in lactose in a targeted manner (exposure). If there is actually a lactose intolerance, the typical symptoms will reappear after a short time.
If carried out correctly and consistently, the lactose intolerance self-test provides a thoroughly reliable result. However, mistakes are often made because the diet is not being followed strictly enough. Therefore, a lactose intolerance test by the doctor is still the most reliable proof.
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