Gut
Lysozyme
A defense enzyme that breaks down bacterial walls, measured in the stool; what the result means has not been established.
Everything about this testWhat it measures
Lysozyme is an enzyme that can break down the cell wall of bacteria. It is found in saliva, tears and mucus, among other places, and in the gut it is released by cells in the intestinal lining and by white blood cells. When the bowel wall is inflamed, more lysozyme can end up in the stool. The test measures how much lysozyme is in a stool sample.
- A sign of inflammation or irritation of the intestinal lining; the meaning for diagnosis has not been established
High
A raised value of one of these markers may fit irritation or inflammation of the gut lining. This is often due to a passing intestinal infection or to anti-inflammatory painkillers (NSAIDs such as ibuprofen or diclofenac). It may also fit a chronic inflammation of the bowel (inflammatory bowel disease, IBD), such as Crohn's disease or ulcerative colitis, especially with long-lasting diarrhea, blood or mucus in the stool and weight loss. The result does not say which cause it is.
Low
For most of these markers, a low value is the usual result. A low value then has no further meaning. It does not rule out a bowel condition; to rule out a chronic inflammation of the bowel, calprotectin in the stool has been studied better.
If your result is abnormal
With an abnormal result without symptoms, no follow-up is usually needed. With bowel symptoms, the GP can request calprotectin in the stool and blood tests, and refer you to a gastroenterologist if there are signs of a chronic inflammation of the bowel.
Reliability
According to the Dutch Society for Clinical Chemistry (NVKC), lysozyme is usually measured in blood or urine, for example to follow the course of sarcoidosis or with kidney damage. For lysozyme in stool there are no agreed cut-off values, and what an abnormal value means has not been established, not even with bowel symptoms. For detecting bowel inflammation, calprotectin in the stool has been studied better.
Limitations
- A gut infection and anti-inflammatory painkillers (NSAIDs) can raise the value.
- Blood in the stool can raise the value.
- Measurement methods and cut-off values differ between laboratories.
How common is this
Bowel symptoms are common: according to the guideline, irritable bowel syndrome affects about 4 in 100 adults in the Netherlands. Chronic inflammatory bowel diseases such as Crohn's disease and ulcerative colitis are much rarer; the guideline gives no Dutch figure for them. How often an abnormal result for these markers occurs in people without symptoms is not known.
Who is this useful for
In people without symptoms, an abnormal result says little, because the meaning has not been established and a passing infection or a painkiller can raise the value. With long-lasting diarrhea or abdominal symptoms, the GP uses calprotectin in the stool to rule out a chronic inflammation of the bowel, and a blood test if celiac disease is suspected. With blood in the stool, unintended weight loss, diarrhea at night or new bowel symptoms after age 50, this test is no substitute for a visit to the GP.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results