RSM Intestinal / ELISA Markers Quick Guide
ELISA (Enzyme-Linked Immunosorbent Assay)
Informational reference on intestinal and ELISA markers offered by
RSM Diagnostics Lab.
Inflammation
Calprotectin
A protein from neutrophils shed into the intestinal lumen, measured
in stool by ELISA. Elevated levels indicate intestinal inflammation
and are strongly associated with inflammatory bowel disease, helping
distinguish inflammatory conditions from functional disorders.
Inflammation
Lactoferrin
An iron-binding protein released by neutrophils; a stool marker of
intestinal inflammation. Elevated lactoferrin helps differentiate
organic inflammation (e.g., IBD) from functional symptoms (IBS) and
can track IBD activity and relapse risk when followed over time.
Inflammation
Lysozyme
An enzyme secreted at sites of gastrointestinal inflammation,
present in neutrophil and macrophage granules. Elevated fecal
lysozyme reflects mucosal inflammation and complements calprotectin
and lactoferrin as an additional inflammatory marker. Particularly
useful in Crohn disease involving macrophage activation.
Inflammation
Eosinophil-Derived Neurotoxin (EDN)
A granule protein released by activated eosinophils; fecal
measurement reflects eosinophil-mediated intestinal inflammation.
Elevated fecal EDN indicates eosinophilic and allergic-type gut
inflammation and has been linked to disease activity and relapse risk
in IBD and non-IgE-mediated food protein-induced gastrointestinal
allergy.
Immune function
Secretory IgA (sIgA)
A mucosal immunoglobulin found in gastrointestinal, respiratory, and
urogenital secretions; a first-line immune defense at mucosal
surfaces. Low sIgA indicates impaired mucosal immunity and increased
susceptibility to gastrointestinal infections; high sIgA suggests
active mucosal immune response or antigenic stimulation.
Immune function
Anti-gliadin IgA
An IgA antibody directed against gliadin, a gluten component in
wheat, barley, and rye. Positive results reflect an immune response
to gluten and should prompt evaluation for gluten-related disorders;
not specific for celiac disease.
Gut barrier
Zonulin
A protein that modulates tight junctions between enterocytes and
regulates intestinal permeability. Elevated stool zonulin has been
proposed as a marker associated with increased intestinal
permeability. Results should be interpreted alongside clinical
findings and other diagnostic information.
Digestive function
Pancreatic elastase
A pancreatic enzyme involved in digestion of proteins, fats, and
carbohydrates; stool levels reflect exocrine pancreatic output. Low
values suggest exocrine pancreatic insufficiency and impaired
digestion; normal levels argue against clinically significant
insufficiency. Values under 100 μg/g indicate severe exocrine
pancreatic insufficiency, 100 to 200 μg/g moderate, and 200 μg/g or
above is generally considered normal.
Digestive function
Stool fat (steatorrhea marker)
A qualitative or quantitative assessment of fat in stool as a marker
of fat malabsorption. Increased stool fat suggests malabsorption or
maldigestion (e.g., exocrine pancreatic insufficiency, celiac
disease, Crohn disease, and other malabsorptive disorders).
Digestive function
Stool carbohydrate marker
Detection of carbohydrates in stool as a marker of carbohydrate
malabsorption. Presence of stool carbohydrates supports carbohydrate
malabsorption and may suggest lactose intolerance, congenital
disaccharidase deficiency, pediatric carbohydrate malabsorption, or
rapid intestinal transit; interpret with diet and symptoms.
Infectious assessment
H. pylori EIA (stool)
An enzyme immunoassay detecting Helicobacter pylori antigens in stool
for noninvasive assessment of gastric colonization. Positive stool
H. pylori antigen supports active infection associated with
dyspepsia, peptic ulcer disease, and increased gastric cancer risk.
Stool antigen testing is recommended for diagnosis of active
infection and for confirmation of eradication after treatment,
performed at least 4 weeks after completion of therapy, with proton
pump inhibitors withheld for an appropriate interval.
Detoxification (add-on)
β-Glucuronidase
A microbial enzyme that hydrolyzes glucuronide conjugates in the
intestinal lumen, offered as an add-on detoxification assessment.
Elevated activity may be associated with increased deconjugation and
enterohepatic recirculation of hormones and xenobiotics; interpret
alongside clinical context and other stool findings.
Disclaimer: This guide is provided for informational
and educational purposes only and is not intended to constitute medical
advice, diagnosis, or treatment. The laboratory tests and interpretive
comments described herein are designed to support, not replace, the
clinical judgment of a licensed healthcare professional. Clinicians must
use their own training, experience, and knowledge of the patient to
determine whether any test is appropriate and how results should be
interpreted and applied. RSM Diagnostics Lab does not assume any
responsibility or liability for clinical decisions, diagnostic
conclusions, or treatment plans made based on this guide or the tests
referenced. Users of this guide are responsible for complying with all
applicable laws, regulations, payer policies, and standard-of-care
guidelines when ordering, interpreting, and acting upon any laboratory
tests.