The easiest way is, of course, the home test. If you have problems that are consistent with lactose intolerance symptoms (bloating, gas, diarrhoea, etc.), try to completely avoid milk for a week. After a few days, the problems should subside. After a week, drink half a litre of milk in the morning, on an empty stomach, and observe. If you end up at the toilet, this is already an almost reliable evidence that milk has an adverse effect on you. On the next day, repeat the same test with lactose-free milk, after which you should have no problems.
Home test is the most practical and the easiest to perform, but also the least reliable. Often, it is not enough to remove from our diet just milk, because lactose can be also found in many processed food products. If during the trial diet lactose is not removed from our menu entirely, the problems do not pass and we continue to falsely believe that the symptoms are not related to lactose. On the other hand, the re-occurrence of the problems after you introduce the milk back to your diet is not unique to lactose intolerance, but it may also apply to other disorders, for example, to milk protein allergy.
Today, as a rule, we carry out several different laboratory tests to diagnose lactose intolerance.
The most widely used is the blood lactose tolerance test, for which you can make an appointment with the doctor. On an empty stomach, in the laboratory the patient ingests a test meal with lactose. Then, the patient’s blood is collected several times in a row and the increase in blood glucose is monitored. If the at a given time glucose does not increase sufficiently, this proves that lactose has not been broken down and absorbed into the blood stream. Blood lactose tolerance test is most easily accessible, but only measures your blood sugar, which is not always associated with the patient’s problems. The blood glucose levels depend on other factors as well, so can many times this lead to false-positive or false-negative results.
At Diagnostic Centre Bled we prefer to use hydrogen breath test, which is also the world’s most renowned test to confirm the diagnosis. On an empty stomach, the patient ingests the test amount of lactose, and then exhales into a special bag for 4 hours, once every half hour. The exhaled air is analysed for determining the level of hydrogen and methane. If a bacterial fermentation of lactose occurs, the resulting gases are partially excreted through the lungs and are present in the breath. Therefore, if the exhaled air contains a characteristic increase in these gases, we know that lactose has not been broken down completely.
Hydrogen breath test is the most sensitive among simple laboratory methods. Its usefulness is significant also due to the fact that it allows us to measure the actual production of gases which cause problems for the patients.
At Diagnostic Centre Bled adults can undergo an examination as self-paying clients, without a referral from their physician. For more information and making an appointment please call our appointment scheduling service.
More technologically demanding and expensive is the 13C-lactose breath test, where following the same principle, a marked increase in the exhaled CO2 is monitored.
In recent years there is also the possibility of genetic testing, but is more suitable for research purposes. Several genetic variants have been identified and associated with primary lactose intolerance. Such genes can be determined with rather expensive laboratory blood tests of blood or other body tissues. The disadvantage of these tests lays in the fact that they do not prove or disprove that a disturbed digestion of lactose is really causing problems to the patient, as this is largely dependent on other factors, for example, the composition of intestinal microflora.
If an endoscopic examination of the upper gastrointestinal tract (gastroscopy) is indicated due to the patient’s symptoms, we may also take a sample of the lining of the small intestine and, under specific conditions, sent it to the laboratory, where they will be able to directly determine the activity of the enzyme lactase. If the latter is reduced, the patient cannot digest lactose properly.