D-xylose absorption test (serum concentration, 2-hour post-oral load)

This test gives your healthcare provider important information about your health. It may be done to look for a specific condition, help confirm a diagnosis, or check how well a current treatment is working for you.

Your doctor may order this test if you have symptoms like chronic diarrhea, weight loss, or unexplained nutrient deficiencies. It’s also used to diagnose conditions like celiac disease, short bowel syndrome, or malabsorption disorders.

During this test, a small sample or measurement is taken so it can be examined in a laboratory or analyzed with special equipment. The results help your care team get a clearer picture of what is happening inside your body.

You’ll drink a solution containing D-xylose, a sugar that your body absorbs through the intestines. Blood is drawn from your arm 2 hours later to measure the concentration of xylose in your serum. This helps determine how efficiently your intestines are working.

Before your test, your healthcare provider will explain the procedure and answer any questions you may have. You may receive specific instructions, such as avoiding certain foods, drinks, or medications, so be sure to follow them carefully.

No special preparation is needed, but avoid taking certain medications (like antibiotics or antacids) that could affect absorption. If you have a history of severe vomiting or nausea, let your doctor know before the test.

During the test, a trained member of your care team will guide you through each step and help you stay as comfortable as possible. Most tests are quick and cause little to no discomfort, and you can usually return to your normal activities right afterward.

You’ll drink the xylose solution, and a blood sample will be taken 2 hours later. The process takes about 30 minutes and is done in a lab setting. You can eat and drink normally afterward.