To investigate absorption in the small intestine after the oral administration of D-xylose, a pentose sugar which is absorbed in the duodenum and the upper jejunum but which is not metabolised in the body.
Fasting for 12 hours and at rest.
- Standard protocol: 25 g D-xylose dissolved in 500 ml water.
- Special protocol (active transport without passive diffusion): 5g D-xylose in 200 ml water.
Children: 0.7 g D-xylose/kg body weight in 100-200 ml water (do not exceed 5 g).
- Empty bladder (discard the urine).
- Oral administration of the correct dose of D-xylose.
- Blood sample (1 fluoride tube) taken after 2 hours, and 5 hour urine collection after ingestion (record the volume of urine).
- Xylose in the blood.
- Xylose in the urine.
Do not carry out if the subject has diarrhea, kidney or liver failure, or a bacterial infection.
Results are invalid if the subject vomited or ate anything during the challenge. Drinking water is allowed