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Xylose Tolerance Test (Fasting, One-, Two-, Three-, Four-, and Five-hour Blood + Five-hour Urine)
- d-Xylose Tolerance
Diagnose intestinal malabsorption syndromes
This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the Food and Drug Administration.
− Children: 1 hour: >30 mg/dL
− Adults: 1 hour: 21−57 mg/dL, 2 hours: 32−58 mg/dL, 3 hours: 19−42 mg/dL, 4 hours: 11−29 mg/dL, 5 hours: 6−18 mg/dL
− Children: 16% to 33% of ingested dose
− Adults: 65 years or younger: >4.0 g/5 hours; older than 65 years: >3.5 g/5 hours
Plasma and urine
2 mL plasma (each specimen) and 10 mL aliquot of five-hour urine
0.6 mL plasma (each specimen) and 0.5 mL aliquot of five-hour urine
Plasma: Draw fasting sample, administer d-xylose dose (see Patient Preparation), and obtain one-, two-, three-, four-, and five-hour samples postdose. Centrifuge and separate plasma from cells immediately. Indicate time drawn (ie, "fasting," "one-hour," etc) on each plasma tube submitted. Urine: Start test in AM. Instruct patient to void completely. Discard this sample. Collect urine for five hours after administration of d-xylose.
Causes for Rejection
Record total five-hour urine volume on the test request form.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|023374||Xylose Tolerance 5-Hr/Urine||016238||Xylose - Fasting||mg/dL||10872-0|
|023374||Xylose Tolerance 5-Hr/Urine||016626||Xylose - 1 hour||mg/dL||23940-0|
|023374||Xylose Tolerance 5-Hr/Urine||016634||Xylose - 2 hour||mg/dL||23943-4|
|023374||Xylose Tolerance 5-Hr/Urine||016246||Xylose - 3 hour||mg/dL||10869-6|
|023374||Xylose Tolerance 5-Hr/Urine||016329||Xylose - 4 hour||mg/dL||13030-2|
|023374||Xylose Tolerance 5-Hr/Urine||016337||Xylose - 5 hour||mg/dL||13031-0|
|023374||Xylose Tolerance 5-Hr/Urine||003510||Xylose, Urine, g/L||g/L||3135-1|
|023374||Xylose Tolerance 5-Hr/Urine||003511||Xylose, Urine, g/5hr||g/5 hr||1646-9|
|023374||Xylose Tolerance 5-Hr/Urine||123101||Disclaimer:||N/A|
|023374||Xylose Tolerance 5-Hr/Urine||016406||Xylose Tolerance (6 Spec)||N/A|