Fecal-reducing substances (carbohydrates) aid in determining the underlying cause of diarrhea. Fecal-reducing substances are chemicals in the stool that can reduce certain chemical reagents. They are often used to diagnose malabsorption or maldigestion disorders in the gastrointestinal system. These reducing substances in the stool are typically sugars that are not properly absorbed and digested by the body, leading to their presence in the feces.
Conditions that can lead to the presence of fecal-reducing substances include:
- Lactose Intolerance: This is a common condition where individuals lack the enzyme lactase needed to digest lactose, a sugar found in dairy products.
- Celiac Disease: In this autoimmune disorder, the body reacts to gluten, a protein found in wheat, barley, and rye. This damage to the small intestine affects nutrient absorption.
- Pancreatic Insufficiency: A malfunctioning pancreas can result in insufficient production of digestive enzymes, which can affect the digestion of carbohydrates.
If the test results are positive for reducing substances, it indicates the presence of undigested or unabsorbed carbohydrates in the stool, suggesting an underlying condition. Elevations in fecal-reducing substances help distinguish between osmotic diarrhea caused by abnormal excretion of various sugars as opposed to diarrhea caused by viruses and parasites. Increased reducing substances in stool are consistent with, but not diagnostic of, primary or secondary disaccharidase deficiency (primarily lactase deficiency) or intestinal monosaccharide malabsorption. Similar intestinal absorption deficiencies are associated with short bowel syndrome and necrotizing enterocolitis.
False-positive reactions due to drugs (salicylates, penicillin, ascorbic acid, nalidixic acid, cephalosporins, and probenecid) are possible.
