<<Disclaimer:  Verify this information before applying it to your situation.>>
 
David,
        The test that you are thinking of is the d-xylose test. It's been
a few years since I has it done, so I hope that I can correctly remember
how it went.
 
        First I has a fasting blood sugar drawn. Then I drank a sulotion
of d-xylose. The amount given is depentant on your body weight. I has
another blood sugar drawn, but I can't remember if it was at one or two
hours. Then I returned to the lab and gave a urine specimen at the end of
five hours. I may or may not have had another blood sugar drawn.
        All of this was done while I was fasting. That is, I has nothing
to eat or drink, except water since 10 pm of the previous evening and ate
and drank nothing except the d-xylose and water during the five hours. I
do remember that it didn't seem as big of an inconvience as I expected.
        The basis of the test is that in cases of malabsorption, the
d-xylose is excreted in the feces as it is not absorbed into the blood.
So the levels of d-xylose should be low in both the blood and urine if
malabsorption is present. This is not a specific test for celiac sprue as
there are other conditions that will cause a malabsorption syndrome.
        Ellen Eagan