Vasoactive intestinal peptide test

Definition

Vasoactive intestinal peptide (VIP) is a test that measures the amount of VIP in the blood.

Alternative Names

VIPoma - vasoactive intestinal polypeptide test

How the Test is Performed

A blood sample is needed.

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. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

This test is used to measure VIP level in the blood. A very high level is usually caused by a VIPoma. This is an extremely rare tumor that releases VIP.

VIP is a substance found in cells throughout the body. The highest levels are normally found in cells in the nervous system and gut. VIP has many functions, including relaxing certain muscles, triggering release of hormones from the pancreas, gut, and hypothalamus, and increasing the amount of water and electrolytes secreted from the pancreas and gut.

VIPomas produce and release VIP into the blood. This blood test checks the amount of VIP in the blood to see if a person has a VIPoma.

Other blood tests including serum potassium may be done at the same time as the VIP test.

Normal Results

Normal values should be less than 70 pg/mL (20.7 pmol/L).

People with VIP-secreting tumors usually have values 3 to 10 times above the normal range.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

A higher-than-normal level, along with symptoms of watery diarrhea and flushing, may be a sign of a VIPoma.

Risks

There is little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking 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 lightheaded
• Multiple punctures to locate veins
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

References

Siddiqi HA, Salwen MJ, Shaikh MF, Bowne WB. Laboratory diagnosis of gastrointestinal and pancreatic disorders. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 22.

Vella A. Gastrointestinal hormones and gut endocrine tumors. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 13th ed. Philadelphia, PA: Elsevier; 2016:chap 38.