Formula weight for 3-O-methyl-D-glucose: 194.18grams
Formula weight for D-xylose: 150.13grams
Protocol (Lutgens et al):
(1) The patient fasts overnight.
(2) The urinary bladder is voided.
(3) The patient drinks 0.5 grams D-xylose and 0.2 grams of OMG (often mixed with other sugars such as L-rhamnose and lactulose, see adjacent sections) in an isotonic solution.
(4) Urine is collected for the next 5 hours.
(5) A light breakfast is permitted 2 hours after drinking the solution.
(6) The volume of the urine at 5 hours is measured and an aliquot is sent for testing.
(7) Measure the amount of D-xylose and OMG in the urine.
urine excretion of D-xylose in mg =
= (urine D-xylose in mg/dL) * (urine volume in mL) / 100
percent of oral dose of D-xylose in the urine =
= (urine excretion of D-xylose in mg) / 500 * 100%
urine excretion of OMG in mg =
= (urine OMG in mg/dL) * (urine volume in mL) / 100
percent of oral dose of OMG in the urine =
= (urine excretion of OMG in mg) / 200 * 100%
D-xylose to OMG ratio =
= (percent of oral dose D-xylose in urine) / (percent of oral dose OMG in urine)
Interpretation:
• The normal ratio is >= 0.28.
• A patient with decreased absorption from celiac disease, diarrhea or other cause will have a reduction in the ratio.
