Comprehensive Stool Analysis + Parasitology — 3 Day

Calprotectin is a calcium- and zinc-binding protein released by neutrophils during intestinal inflammation. Its concentration in stool reflects mucosal neutrophil activity and is stable at room temperature for several days, making it a practical marker of inflammatory bowel disease and other inflammatory enteropathies.

Calprotectin distinguishes organic inflammatory bowel disease from functional bowel disorders with high sensitivity and negative predictive value. Persistent elevation above 50 µg/g warrants endoscopic investigation; levels above 150 µg/g are strongly associated with active IBD. Serial measurements track disease activity and therapeutic response.

Secretory IgA is the predominant immunoglobulin at mucosal surfaces, synthesised by plasma cells in the lamina propria, dimerised, and actively transported across the epithelium. It binds luminal antigens, pathogens, and toxins, preventing epithelial adhesion and invasion while tolerating commensal flora.

Faecal sIgA reflects mucosal immune competence. Low levels may accompany immune deficiency, chronic stress, malnutrition, or dysbiosis; high levels can indicate an active immune response to enteric infection or dysbiosis. Interpretation is nuanced and must be contextualised with clinical presentation and other markers.

Pancreatic elastase-1 is a proteolytic enzyme synthesised exclusively by the pancreatic acinar cells, secreted into the duodenum, and passed intact through the intestine. Because it is not degraded during transit, faecal concentration reflects pancreatic exocrine output rather than intraluminal dilution or degradation.

PE-1 is the non-invasive test of choice for exocrine pancreatic insufficiency. Values below 200 µg/g indicate insufficiency; below 100 µg/g confirm severe insufficiency. It is sensitive in moderate-to-severe insufficiency but may miss mild disease. False-low results occur with watery diarrhoea due to dilution.

Occult blood in stool reflects gastrointestinal bleeding that is not grossly visible. Immunochemical methods detect intact human haemoglobin from the lower gastrointestinal tract, while guaiac-based methods detect haem peroxidase activity and may capture upper tract bleeding but are prone to dietary interference.

A positive result prompts investigation for colorectal neoplasia, inflammatory bowel disease, angiodysplasia, or other bleeding lesions. Sensitivity for cancer and large adenomas is moderate in a single sample; serial samples improve yield. Negative results do not exclude intermittent or right-sided lesions.

Lactobacillus species are Gram-positive lactic-acid-producing commensals predominantly in the small intestine and vagina. They ferment carbohydrates to lactate, lower luminal pH, produce antimicrobial compounds, and modulate local immune responses, contributing to colonisation resistance.

Reduced Lactobacillus abundance may accompany dysbiosis, antimicrobial therapy, or inflammatory states. Interpretation is contextual; the microbiome is an ecosystem, and single-taxon abundance is less informative than the overall community structure and clinical correlation.

Bifidobacterium species are obligate anaerobes that dominate the infant gut and remain prominent in the adult colon. They ferment complex carbohydrates to short-chain fatty acids, support epithelial barrier integrity, and modulate systemic immune tone.

Reduced Bifidobacterium is reported in dysbiosis, irritable bowel syndrome, and inflammatory bowel disease, but causality is not established. Probiotic strains are used therapeutically, yet clinical benefit is strain- and indication-specific.

Enteric pathogens include Salmonella, Shigella, Campylobacter, enterohaemorrhagic and enterotoxigenic Escherichia coli, Yersinia, Vibrio, and Clostridium difficile. Detection methods vary by organism; culture remains the standard for many, while molecular methods improve sensitivity for fastidious or slow-growing species.

Positive cultures guide antimicrobial therapy and infection-control measures. Molecular detection may identify non-viable or colonising organisms; clinical correlation is essential. Some panels detect toxin genes (C. difficile toxin A/B, Shiga toxin) to refine pathogenicity.

Candida species and other yeasts are normal low-abundance commensals in the gut. Overgrowth may follow antimicrobial therapy, immunosuppression, or dietary factors. Most are not invasive in immunocompetent hosts, but high luminal burdens can contribute to dysbiosis and non-specific gastrointestinal symptoms.

Candida overgrowth is a controversial entity; moderate-to-heavy growth (≥2+) in symptomatic patients with clear predisposing factors may warrant a trial of antifungal therapy, though evidence is limited. Asymptomatic colonisation does not require treatment.

Intestinal parasites include protozoa (Giardia lamblia, Entamoeba histolytica, Cryptosporidium, Cyclospora, Blastocystis hominis) and helminths (roundworms, tapeworms, flukes). Detection relies on microscopic examination of preserved stool; sensitivity improves with multiple specimens collected on separate days to capture intermittent shedding.

Detection of pathogenic parasites (Giardia, Cryptosporidium, E. histolytica, helminths) mandates therapy. Blastocystis hominis is common and often non-pathogenic; treatment is reserved for symptomatic patients without other explanation. Three-day collection substantially improves yield over single-sample O&P.

Acetate, propionate, and butyrate are the principal fermentation products of dietary fibre by colonic anaerobes. Butyrate is the preferred fuel for colonocytes, regulates epithelial differentiation and barrier function, and modulates local and systemic inflammation. Acetate and propionate are absorbed and metabolised systemically.

Low butyrate production is associated with inflammatory bowel disease, irritable bowel syndrome, and metabolic dysfunction, though causality is unproven. SCFA profiles reflect microbial metabolic activity and substrate availability; interpretation is exploratory and should guide dietary and prebiotic interventions rather than pharmacotherapy.

Stool pH reflects colonic fermentation and absorption. Carbohydrate fermentation by saccharolytic bacteria produces acidic short-chain fatty acids, lowering pH; protein putrefaction and ammonia production raise pH. Rapid transit and malabsorption also shift pH.

Low pH (<6.0) may accompany carbohydrate malabsorption or excessive fermentation; high pH (>7.5) suggests putrefactive dysbiosis or reduced SCFA production. Interpretation is contextual and must be integrated with SCFA measurements, clinical symptoms, and dietary intake.