Dxylosetestet

Dxylosetestet, commonly referred to as the D-xylose test, is a diagnostic procedure used to assess the absorptive capacity of the proximal small intestine. D-xylose is a simple sugar absorbed directly by the intestinal mucosa without reliance on pancreatic enzymes and is excreted largely unchanged in the urine. The test helps differentiate intestinal mucosal disorders from pancreatic insufficiency.

Procedure and interpretation. After an overnight fast, a defined oral dose of D-xylose (typically 5 grams) is given. Urine is collected for about five hours, and the total excreted xylose is measured. In some protocols, a serum D-xylose level is also checked around the two-hour mark. Normal urinary excretion is generally greater than about 4 grams in five hours. Values below this threshold suggest impaired intestinal absorption and possible mucosal disease, such as celiac disease, Crohn’s disease, or bacterial overgrowth. The test is not disease-specific and must be interpreted in the context of clinical findings and other investigations.

Limitations and status. The D-xylose test is influenced by renal function, hydration, completeness of urine collection, age, and concurrent medications, which can affect accuracy. It is less commonly used today, having been largely supplanted by more specific serologic tests, imaging, and comprehensive approaches to malabsorption. However, Dxylosetestet may still be employed in certain settings or when newer tests are unavailable.

See also: D-xylose test, intestinal malabsorption, pancreatic insufficiency.