What does a very high calprotectin level indicate in a patient with diarrhea?

From the Guidelines

A very high calprotectin level in a patient with diarrhea strongly indicates active intestinal inflammation, most commonly inflammatory bowel disease (IBD) such as Crohn's disease or ulcerative colitis. According to the most recent and highest quality study, a threshold value of 50 μg/g for fecal calprotectin is recommended to optimize sensitivity for IBD 1. However, levels above 250 μg/g are considered significantly elevated, with values exceeding 1000 μg/g suggesting severe active inflammation 1. This finding warrants prompt referral to a gastroenterologist for further evaluation, including colonoscopy with biopsies to confirm the diagnosis and determine the extent and severity of inflammation.

Some key points to consider in the management of a patient with a very high calprotectin level and diarrhea include:

• The need for distinction between IBD and infectious causes of diarrhea, as treatment approaches differ significantly
• The potential use of antidiarrheal medications like loperamide for mild symptoms, though these should be avoided if severe inflammation is suspected due to risk of toxic megacolon
• The importance of stool cultures and other infectious workup alongside calprotectin testing to rule out infectious causes
• The high sensitivity of fecal calprotectin as a biomarker for intestinal inflammation, helping to differentiate inflammatory from non-inflammatory causes of chronic diarrhea such as irritable bowel syndrome 1.

Given the potential for severe morbidity and mortality associated with untreated IBD, prompt referral to a specialist and further evaluation are crucial. The use of fecal calprotectin as a screening tool can help identify patients who require more urgent evaluation and treatment, ultimately improving outcomes and quality of life for patients with IBD 1.

From the Research

High Calprotectin Levels and Diarrhea

A very high calprotectin level in a patient with diarrhea can indicate several things:

• Inflammatory bowel disease (IBD) such as Crohn's disease or ulcerative colitis, as elevated fecal calprotectin levels are associated with intestinal inflammation 2, 3, 4, 5
• Bacterial infections such as Salmonella or Campylobacter, which can cause higher fecal calprotectin levels compared to viral infections like rotavirus or norovirus 6
• Severe or moderate disease activity, as fecal calprotectin concentrations are elevated in patients with more severe symptoms 6
• Subclinical mucosal inflammation, which can be detected by fecal calprotectin even in patients with no obvious symptoms 2

Possible Causes of High Calprotectin Levels

Some possible causes of high calprotectin levels in patients with diarrhea include:

• Inflammatory bowel disease (IBD) 2, 3, 4, 5
• Infectious diarrhea caused by bacteria such as Salmonella or Campylobacter 6
• Other inflammatory conditions affecting the gastrointestinal tract 4
• Colorectal cancer, which can cause elevated fecal calprotectin levels 4

Clinical Implications

High calprotectin levels in patients with diarrhea can have several clinical implications:

• The need for further investigation, such as endoscopy or imaging studies, to rule out IBD or other inflammatory conditions 2, 3
• The potential for disease relapse in patients with IBD, as elevated fecal calprotectin levels are associated with an increased risk of relapse 2
• The need for monitoring of disease activity and adjustment of treatment plans in patients with IBD 2, 3