Lactoferrin

Lactoferrin is a stool (fecal) test that is used to detect inflammation in the intestines. Intestinal inflammation is associated with, for example, some bacterial infections and, in people with inflammatory bowel disease (IBD), it is associated with disease activity and severity. The test may be ordered to distinguish between IBD and non-inflammatory disorders and to monitor IBD disease activity.

A healthcare practitioner may order a lactoferrin test to help investigate the cause of a person's persistent watery or bloody diarrhea. The test may be ordered along with other stool tests, such as a stool culture to detect a bacterial infection, a test for ova and parasites (O&P), a stool white blood cell test, and/or a fecal occult blood test.

If a healthcare practitioner suspects inflammation, then blood tests that detect inflammation in the body, such as an ESR (erythrocyte sedimentation rate) and/or CRP (C-reactive protein), may also be ordered. Testing is performed both to help determine what is causing a person's symptoms and to rule out conditions with similar symptoms. This means that additional blood and stool testing may be performed depending on the suspected causes.

If a person has been diagnosed with IBD, then a lactoferrin test may be ordered to monitor disease activity and to help evaluate its severity. For example, if a person has a moderately elevated lactoferrin, then testing may be repeated several weeks later to see if it has stayed moderately elevated, increased, or returned to normal.

A lactoferrin test may be ordered to help determine whether an endoscopy is indicated if IBD is suspected. A diagnosis of IBD is usually confirmed by performing an endoscopy (colonoscopy or sigmoidoscopy) to examine the intestines and by obtaining a small tissue sample (biopsy) to evaluate for inflammation and changes in tissue structures. This testing is invasive and is less likely to be necessary if inflammation is not present.

A lactoferrin test may be ordered when a person has symptoms that suggest that intestinal inflammation may be present and when a healthcare practitioner wants to distinguish between IBD and a non-inflammatory bowel condition.

Signs and symptoms of intestinal inflammation will vary from person to person and over time. They may include one or more of the following:

• Bloody or watery diarrhea
• Abdominal cramps or pain
• Fever
• Weight loss
• Rectal bleeding
• Weakness

Testing for lactoferrin may be performed when a healthcare practitioner wants to determine whether an endoscopy (colonoscopy or sigmoidoscopy) is likely or less likely to be necessary.

When a person has been diagnosed with IBD, a lactoferrin test may be ordered whenever a flare-up is suspected, both to confirm disease activity and to evaluate its severity.

An elevated lactoferrin level in the stool indicates that inflammation is likely present and active in the digestive tract but does not indicate either its location or cause. In general, the degree of elevation is associated with the severity of the inflammation. An endoscopy (colonoscopy or sigmoidoscopy) may be indicated as a follow-up test.

Increases in lactoferrin are seen with IBD but also with other inflammatory conditions, with intestinal bacterial infections, some parasitic infections, and with colon cancer.

In newly diagnosed people with IBD, concentrations of lactoferrin may be very high.

A low level of lactoferrin means that a bowel disorder is likely non-inflammatory. Examples of these include diarrhea due to viral digestive tract infections and irritable bowel syndrome (IBS). Unlike IBD, IBS does not cause inflammation. Rather, it causes cramp-like stomach pains and spasms with bouts of diarrhea and/or constipation. People with low lactoferrin results are less likely to require an endoscopy.

A moderate lactoferrin level may be seen in those with less active IBD. The result indicates that there is likely some inflammation present. If a repeat test shows that the lactoferrin has increased, then the person's condition may be worsening.

Lactoferrin is related to another stool test, calprotectin. Both are substances that are released by white blood cells in the stool and are associated with intestinal inflammation. Of the two tests, calprotectin has been the most extensively studied and it is ordered more frequently than lactoferrin. Usually one or the other will be ordered but not both.

A baby that is being breast-fed could potentially have a false-positive result because of lactoferrin present in the mother's breast milk.

Current evidence suggests that there is not a significant benefit to performing both tests as they both detect intestinal inflammation.