The currently preferred diagnosis is made by an endoscopic sample of liquid from the small intestine. However, as this is a rather elaborate and uncomfortable method for the patient, bacterial overgrowth breath tests are usually used for indirect diagnosis.
It is the same principle as in the breath tests for suspected lactose or fructose intolerance: you drink a liquid and measure the concentration of hydrogen in the exhaled air at regular intervals. As a test substance glucose and / not lactose used se.
The preparation for breath test may vary from doctor to doctor. A typical pre-dairy diet is restricted to meat, fish, eggs, hard cheese, poultry, chicken broth, salt, oil and pepper and possibly white rice. In addition, certain medications must be discontinued for a long time before the test.
Glucose Breath Test
Glucose is metabolized by humans in the upper part of the small intestine, but can also be digested by bacteria that produce hydrogen. When the glucose breath test raises the hydrogen level, it means that there are bacteria in the upper part of the small intestine that “snatch” the glucose from our own digestion.
Such a test result is very reliable, but has the disadvantage that it says nothing about whether SIBO is also in the lower part of the small intestine, which is very likely in the constipation type.
Lactulose breath test
People cannot digest lactulose – only the bacteria in the intestine do so, producing gas (hydrogen, methane). The advantage of this test is that it can diagnose bacterial growth in the middle and lower part of the small intestine. It is believed that this happens more frequently.
In both the glucose and lactulose tests, the test result is considered positive if the hydrogen value is ≥20 ppm above baseline within 90 minutes.
If the glucose test is negative, an additional lactose test is required to test for SIBO in the mid and lower small intestine sections.
The interpretation of the test result can vary greatly. Among other things, it also states that bacterial overgrowth breath tests are useful in carbohydrate digestive disorders, constipation and flatulence, but not in the assessment of intestinal transit time.