Diagnostics - Stool Testing Flashcards
What does a stool test provide?
A stool test provides a comprehensive snapshot of digestive function and GI microbiome. It is helpful for GI complaints and chronic systemic illnesses where poor GI function might be relevant, including metabolic endotoxaemia.
What is metabolic endotoxaemia?
Metabolic endotoxaemia is a persistent, low-grade inflammation caused by increased circulating endotoxins (LPS). It often happens with poor GI barrier integrity and can be a risk factor for chronic diseases like insulin resistance and autoimmunity.
What do stool tests evaluate?
Stool tests evaluate microbial markers (commensal bacteria, pathogens, parasites, pathobionts, mycology), and host markers (immune, digestive, inflammatory, intestinal permeability, occult blood).
What are the methodologies used in stool testing?
Methodologies include polymerase chain reaction (PCR), culture, and microbiology assessment.
How should stool test results be interpreted?
Stool test results should be analyzed considering patient symptoms, diet, and health history. The presence of a microbe or marker does not always indicate disease. Correlate results with symptoms and use lab reference guides for interpretation.
What dietary factors influence the microbiota?
Dietary models, like FODMAPs or high-fat diets, significantly alter the gut microbiota, affecting the presence of certain bacteria and health outcomes.
What does the marker calprotectin indicate?
Calprotectin is an inflammation marker. Levels >50 µg/g indicate inflammation, with NHS screening for IBD done at levels over 175 µg/g.
What does Eosinophil Protein X indicate?
Eosinophil Protein X is raised with intestinal inflammation, food allergies, parasites, and colitis. Normal is 1.1 mcg/g; moderate is 1.1–4.6 mcg/g; high is >4.6 mcg/g.
What does high beta-glucuronidase indicate?
High beta-glucuronidase, often elevated due to dysbiosis or a western diet, can impact estrogen excretion, leading to increased circulating estrogen.
What is pancreatic elastase used for in stool tests?
Pancreatic elastase measures digestive function. Normal is 200-500 µg/g; <200 µg/g indicates digestive support is needed, 100-200 µg/g indicates pancreatic insufficiency, and <100 µg/g indicates severe insufficiency.
What do high fecal fats indicate?
High fecal fats indicate fat maldigestion, often associated with pancreatic insufficiency, SIBO, or hypochlorhydria.
What does sIgA indicate in stool tests?
Secretory IgA (sIgA) measures immune defense in the GI mucosa. Low levels (<100 µg/g) indicate chronicity or susceptibility to GI infections, while high levels (>750 µg/g) suggest an upregulated immune response.
What does beta-defensin 2 indicate?
Beta-defensin 2 is an antimicrobial response marker. High levels (>62 ng/g) suggest immune response to microbial breach or GI inflammation, such as in ulcerative colitis.
What does zonulin indicate in stool tests?
Zonulin family peptides indicate intestinal permeability. High levels (>100 µg/g) suggest severe permeability issues like dysbiosis or coeliac disease.
What are short-chain fatty acids (SCFAs), and why are they important?
SCFAs are by-products of bacterial fermentation of fiber, primarily butyrate, propionate, and acetate. Butyrate fuels colon cells and modulates inflammation. Low SCFAs are linked to low-fiber diets or antibiotic use.
