Stool Analysis

Faecal Calprotectin

Faecal calprotectin is a calcium-binding neutrophil protein serving as a biomarker for intestinal inflammation. It is primarily used to differentiate between inflammatory bowel disease (IBD) and functional gastrointestinal disorders such as irritable bowel syndrome (IBS). Elevated levels suggest inflammation within the gut, as seen in Crohn’s disease, ulcerative colitis, or infective enterocolitis.

In children presenting with chronic diarrheoa, abdominal pain, or growth failure, faecal calprotectin provides a non-invasive means to assess the need for further endoscopic evaluation.

Stool Alpha-1 Antitrypsin Level

Alpha-1 antitrypsin (A1AT) is a plasma protein resistant to intestinal degradation. Its presence in stool reflects protein loss through the GI tract (leaky gut or protein-losing enteropathy). Elevated stool A1AT indicates excessive protein leakage, which can occur in intestinal lymphangiectasia, severe inflammatory disease, or post-surgical states.

It is particularly useful in children with unexplained hypoalbuminemia, edema, or chronic diarrhea.

Stool for Bacterial and Viral Analysis

Microbiological stool examination remains a cornerstone of evaluating infectious diarrhea. It identifies pathogens such as giardiasis, protozoa (amoaeba), cryptosporidium, Salmonella, Shigella, Campylobacter, E. coli (including enteropathogenic strains) and Clostridioides difficile.

Molecular assays (PCR) or antigen detection can identify common viral agents such as rotavirus, adenovirus, norovirus, and astrovirus.

These tests are crucial in children with acute or persistent diarrhea, especially in cases of outbreaks, immunocompromise, or systemic illness. They also guide infection control measures and antibiotic stewardship.

Stool for Reducing Substances

Testing for reducing substances (mainly sugars such as glucose, lactose, or fructose) assesses carbohydrate malabsorption. A positive test indicates unabsorbed sugars in stool, often due to disaccharidase deficiency (e.g., lactase deficiency) or secondary carbohydrate malabsorption following mucosal injury.

It is valuable in infants and young children with chronic diarrhea, bloating, or acidic stools, especially following viral gastroenteritis (secondary lactose intolerance) or in congenital enzyme deficiencies.

Stool Elastase

Pancreatic elastase is an enzyme secreted by the pancreas that remains stable during intestinal transit. Measurement of fecal elastase-1 is a reliable indicator of exocrine pancreatic function.

Low stool elastase levels suggest pancreatic insufficiency, as seen in cystic fibrosis, Shwachman–Diamond syndrome, or chronic pancreatitis. This test is particularly important in evaluating children with failure to thrive, steatorrhea, or fat-soluble vitamin deficiencies.

Conclusion

Stool analysis in children offers a non-invasive yet highly informative window into gastrointestinal health. By combining inflammatory markers (faecal calprotectin), protein loss indicators (stool A1AT), pancreatic function tests (stool elastase), carbohydrate absorption assessment (reducing substances), and pathogen detection, clinicians can achieve a comprehensive evaluation of gut pathology.