D-xylose absorption

What is D-Xylose Absorption?

D-Xylose absorption test is a screening test which helps to diagnose malabsorption by measuring how much and how quickly the body can absorb the sugar D-xylose (a five-carbon sugar molecule). In this test, a person drinks a sugar solution, and then a sample of blood and/or urine is measured at specific intervals for up to five hours. If the body is not absorbing D-xylose properly, lower than normal levels of xylose will be found in the patient's urine or blood.

Preparation and Procedure

The patient should fast for at least 6 hours before the test. The test usually begins with drinking a solution composed of 25 grams (0.88 oz) of D-xylose in 250 millilitres (8.5 fluid ounces) of water. Blood samples are then taken at 0, 30, 60, 120, and 180 minutes after ingestion for analysis of D-xylose. Urine specimens may also be taken for eight hours following ingestion, so that the total amount of xylose excreted in the urine can be measured.


  • Urine D-Xylose Test - This test measures the amount of xylose in the urine for 8 hours after the patient drinks the xylose solution.
  • Serum D-Xylose Test - In this test, a blood sample is taken to measure the concentration of xylose in the serum after the patient drinks the xylose solution.


The test is considered safe and poses very little risk to the patient. However, patients with severe or uncontrolled diabetes may experience symptoms like low blood sugar and dehydration. Please inform your doctor if you have any medical conditions before undergoing the test.

Why is it needed?

The D-Xylose absorption test is used to diagnose malabsorption syndromes, which are disorders that cause poor absorption of nutrients in the intestines. Malabsorption can lead to a variety of symptoms such as bloating, abdominal pain or cramps, diarrhea, constipation, fatigue, weakness and weight loss. The D-Xylose absorption test can help to assess the degree of malabsorption in the intestines.

When is it used?

The D-Xylose absorption test is usually used when a person is experiencing symptoms of malabsorption in order to confirm a diagnosis. It may also be used to monitor the effectiveness of a treatment plan for a patient with a malabsorption disorder. The test can be used to diagnose a variety of conditions including celiac disease, pancreatic insufficiency, Crohn's disease, bacterial overgrowth, chronic diarrhea, and some forms of food allergies.