What is it?
This is a simple, painless test to see how well the small intestine is working.

It may be carried out to assess damage to the lining of the small intestine due to inflammation in Crohn's disease.

Preparation
Alcohol should not be taken for 48 hours prior to the test.

Medications such as aspirin and other non-steroidal anti-inflammatory drugs (Volterol, Ibuprofen etc.) should also be avoided for 24 hours before the test.

No solid food should be eaten from midnight prior to the test.

At least 2-3 cups of clear fluids (water, fruit squash, black tea or coffee) should be taken on the morning of the test. This is to ensure that a good amount of urine will be passed.

How is it performed?
On arrival at the department the test will be explained to you and you will be given a sweet test solution to drink. This contains 2 substances labeled with a small amount of radioactivity - 51Cr EDTA and 14C mannitol.

You may eat and drink normally 1 hour after the test has begun but no alcohol must be taken until the test is completed.

All urine is to be collected for the next 6 hours into the container provider. At the end of this period you should try and empty the bladder to ensure that a full 6 hour collection is obtained. The completed container should be returned to the Department of Nuclear Medicine as soon as possible.

After the test
The urine is analysed for the amount of radioactive tracers present. Mannitol is normally absorbed completely and all of this should be excreted in the urine. EDTA is a larger molecule and does not pass through the healthy intestinal wall. It is therefore not absorbed into the blood stream and should not be present in the urine under normal circumstances. The damage to the small intestine is calculated from the amount of mannitol in relation to the EDTA in the collected urine. The results will be sent to your doctor who will decide what to do next.