D-Xylose Test

Purpose
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.

Subject preparation
Fasting for 12 hours and at rest.

Product
Xylose

Dose
Adults:
- 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).

Protocol
- 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).

Assays
- Xylose in the blood.
- Xylose in the urine.

Contraindications
Do not carry out if the subject has diarrhea, kidney or liver failure, or a bacterial infection.

Comment
Results are invalid if the subject vomited or ate anything during the challenge. Drinking water is allowed