Vasoactive intestinal polypeptide (VIP) is a substance found throughout the body. The highest levels are normally found in the nervous system and gut. VIP has many functions:
- It helps control or send nerve signals
- It helps relax certain muscles along the gastrointestinal tract
- It increases the amount of water and electrolytes released from the pancreas and gut
- It triggers the release of hormones from the pancreas, gut, and hypothalamus
- It helps break down fat and glycogen
- It stimulates bile flow
- It blocks gastrin and gastric acid release
A blood test can be done to find out how much VIP you have in your blood.
How the test is performed
A blood sample is needed. For information on how this is done, see: Venipuncture.
How to prepare for the test
You should not eat or drink anything for 4 hours before the test.
How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test is used to confirm the presence of a VIPoma, a tumor that releases VIP.
Normal values range from less than 75 – 190 pg/mL (picograms per milliliter).
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
What abnormal results mean
A higher-than-normal level, along with symptoms of watery diarrhea and flushing, may be a sign of a VIPoma.
What the risks are
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Jensen RT. Pancreatic endocrine tumors. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 205.