Which test assesses the absorption of monosaccharides by the intestines?

The D-xylose absorption test is specifically designed to evaluate the intestines' ability to absorb monosaccharides. D-xylose is a five-carbon sugar that doesn’t require digestive enzymes for absorption, allowing it to be absorbed directly in the small intestine. When this test is conducted, the amount of D-xylose that is absorbed into the bloodstream and subsequently excreted in the urine reflects the functional status of the intestinal mucosa. Low levels of D-xylose in the urine suggest malabsorption due to a problem in the intestinal lining, while normal levels indicate that the malabsorption is more likely due to other factors, such as pancreatic insufficiency, as the test bypasses enzyme digestion requirements.

In contrast, the glucose tolerance test assesses the body's ability to metabolize glucose and is primarily used for diagnosing diabetes or glucose intolerance. The fructose tolerance test, similar to the glucose test, evaluates how well the body absorbs and metabolizes fructose but does not specifically target monosaccharide absorption from the intestines overall. The lactose tolerance test is used to assess the body's ability to digest lactose, a disaccharide, rather than monosaccharides. Thus, when determining the absorption of monosaccharides, the D-xylose