Water, Fat, Nitrogen, And Sugar Content in Feces: Reference Intervals in Children (General Clinical Chemistry‪)‬

Pancreatic insufficiency, cystic fibrosis, celiac disease, Crohn's disease, and hepatic disorders are among several diseases that can produce malabsorption-maldigestion. In these syndromes, diarrhea, steatorrhea, and important nutrient stool losses can be present. Protein and carbohydrate losses can also be considerable in these diseases. The quantification in feces of principal nutrients such as water, fat, nitrogen, sugar, and starch remains one of the most important diagnostic tools for these syndromes (1,2). Fat malabsorption is not an early finding in these syndromes, and other methods often identify the disorder before steatorrhea develops. Nevertheless, measurement of daily stool fat excretion is the most direct and accurate method of demonstrating fat malabsorption (3). Water content is also indispensable for assessing digestive functions and certain syndromes such as constipation and diarrhea (4). Protein malabsorption (measured as nitrogen excretion) can be found in many gastrointestinal diseases, and the evaluation of nitrogen balance is essential in the management of patients with nutritional problems (5) and in subjects with suspected protein maldigestion (6). Fecal carbohydrate loss measurement is also important in the diagnosis of malabsorption syndromes (7, 8), although certain amounts of starch are malabsorbed even under physiologic conditions (9).