Calprotectin Levels in SIBO Patients

Diagnostic Considerations

The American Gastroenterological Association recommends investigating alternative causes of inflammation when encountering elevated calprotectin in a patient with suspected SIBO, rather than attributing it to bacterial overgrowth, as calprotectin levels are not elevated in SIBO patients 1, 2
Elevated calprotectin levels (50-60 mg/g) have a pooled sensitivity of 0.81 and specificity of 0.87 for detecting organic inflammation in inflammatory bowel disease (IBD) patients, according to the American Gastroenterological Association 1, 2
In post-surgical Crohn's patients, rising calprotectin levels indicate anastomotic recurrence rather than concurrent SIBO, as stated by the British Society of Gastroenterology 3

The European Society of Gastrointestinal Endoscopy suggests treating SIBO and elevated calprotectin as separate conditions, requiring distinct therapeutic approaches, such as antibiotics (typically rifaximin 550mg twice daily for 1-2 weeks) for SIBO and anti-inflammatory therapy for the inflammatory process 3, 4

The European Society of Gastrointestinal Motility recommends that SIBO and elevated inflammatory markers should be treated as separate conditions: antibiotics for SIBO and anti-inflammatory therapy for the inflammatory process, with antibiotics such as rifaximin 550mg twice daily for 1-2 weeks 5
The absence of elevated inflammatory markers does not exclude SIBO, as SIBO is diagnosed through breath testing or small bowel aspiration, not inflammatory biomarkers, according to the Gut journal guidelines 5

Elevated fecal calprotectin levels, with a pooled sensitivity of 0.81 and specificity of 0.87, can indicate organic inflammation in inflammatory bowel disease (IBD), and should prompt investigation for concurrent inflammatory conditions rather than attributing the elevation to SIBO alone, as suggested by the Gut journal 5

Elevated fecal lactoferrin indicates moderate to severe endoscopic inflammation, particularly in ulcerative colitis, with very low certainty of evidence for ruling in inflammation, according to the American Gastroenterological Association guidelines 6, 7
Lactoferrin elevation reflects mucosal inflammatory disease, not bacterial overgrowth, as stated by the American Gastroenterological Association 6

Low secretory IgA (sIgA) suggests immune deficiency states such as common variable immunodeficiency (CVID), which is a risk factor for developing SIBO as a secondary condition, as recommended by the American Academy of Allergy, Asthma, and Immunology 8
CVID presents with IgG <5 g/L plus low IgA or IgM, absence of plasma cells on biopsy, and recurrent infections, according to the American Academy of Allergy, Asthma, and Immunology 8

Inflammatory bowel disease (Crohn's disease or ulcerative colitis) should be considered when encountering elevated inflammatory markers, as stated by the Crohn's and Colitis Foundation 8
Eosinophilic gastroenteritis, autoimmune enteropathy, and common variable immunodeficiency are other conditions to consider when investigating elevated inflammatory markers, as recommended by the American Gastroenterological Association 8