A vasoactive intestinal peptide test measures VIP in plasma to help evaluate chronic watery diarrhea and certain tumors. Learn what high or low results mean.
The vasoactive intestinal peptide test is a blood test that measures how much VIP is circulating in your plasma. Doctors use it mainly to investigate long-lasting, high-volume watery diarrhea when a rare hormone-secreting tumor called a VIPoma is suspected. A normal result usually makes that tumor unlikely, while a clearly elevated level usually leads to imaging and more hormone testing.
What the Vasoactive Intestinal Peptide Test Measures
VIP is a 28-amino-acid peptide that acts as both a hormone and a neurotransmitter in the gut, pancreas, and nervous system. It relaxes smooth muscle, stimulates the release of water and electrolytes into the intestine, and helps regulate blood flow. Many people first search what is vasoactive intestinal peptide after seeing the term on a lab order or in a research article.
The test measures VIP in plasma, the liquid portion of blood. Because VIP is released in short bursts and breaks down quickly, the sample has to be collected, chilled, and frozen on a strict timeline. Results are reported in picograms per milliliter (pg/mL) or picomoles per liter (pmol/L), and normal ranges differ from one laboratory to the next.
When a VIP Plasma Blood Test Is Ordered
A VIP level is not part of routine blood work. A clinician usually orders a vasoactive intestinal polypeptide blood test only when several specific findings line up:
- Watery diarrhea that lasts for weeks or months
- Stool volumes above roughly 1 to 3 liters per day
- Diarrhea that continues even when you stop eating
- Low potassium, low bicarbonate, or dehydration
- Flushing, low blood pressure, or unexplained high blood sugar
- A pancreatic, adrenal, or nerve-tissue mass seen on imaging
VIPomas are rare, so most people who are tested do not have one. The test works best as one piece of a larger evaluation rather than as a stand-alone diagnosis.
VIP Plasma Levels: Normal Range and What High Results Mean
There is no single universal cutoff, but most labs use a fasting reference range that tops out around 50 to 75 pg/mL.
| Fasting VIP plasma level | Typical interpretation |
|---|---|
| Below 75 pg/mL | Normal at most labs; a VIPoma is unlikely |
| 75–200 pg/mL | Borderline; repeat testing and clinical review are usually recommended |
| Above 200 pg/mL | Strongly suspicious for a VIPoma when large-volume watery diarrhea is also present |
Units and cutoffs vary, and a value that is high at one lab may fall inside the range at another. A VIPoma is typically diagnosed only when a high level is paired with classic symptoms and confirmed on imaging.
What Causes High VIP Levels?
A tumor is not the only reason for a high vasoactive intestinal peptide reading. Common explanations include:
- VIPoma — a rare neuroendocrine tumor, usually located in the pancreas
- Other neuroendocrine tumors — ganglioneuroma, neuroblastoma, or pheochromocytoma
- Kidney problems — the kidneys clear VIP, so levels can rise in chronic kidney disease
- Intestinal ischemia or obstruction — tissue stress can release extra VIP
- Sampling conditions — a non-fasting draw, acute stress, or poor sample handling
Interest in vasoactive intestinal peptide covid research grew during the pandemic, when small studies measured VIP in patients with severe infection. Those findings remain experimental and are not used to diagnose or treat anyone in routine practice.
What Low VIP Plasma Levels Mean
A low VIP plasma level is rarely meaningful on its own, and no standard diagnosis is based on it. In many cases a low result reflects a handling problem, because VIP degrades within minutes if the tube is not chilled and frozen promptly. Research has examined low VIP in autonomic and inflammatory conditions, but that work has not translated into routine clinical testing.
How the Test Is Performed and How to Prepare
Preparation and handling matter more for this test than for a typical blood draw. Most labs follow a protocol like this:
- Fast for 8 to 12 hours before the draw, because eating stimulates VIP release.
- Tell your clinician about every medication you take, including acid reducers and blood pressure drugs.
- Have blood collected into a chilled tube, often with a preservative such as aprotinin.
- Centrifuge the sample while cold and freeze the plasma immediately.
- Ship the frozen sample on dry ice to a specialty reference laboratory.
Because so few labs run VIP in-house, results often take one to three weeks. A single mishandled sample can produce a falsely low value, which is one reason repeat testing is common.
Reading Your VIP Blood Test Results
The number alone does not tell you what is wrong. Your clinician will compare it with the reference range printed on your report and with how you actually feel.
If the level is clearly high, the next steps usually include a CT or MRI of the pancreas, an endoscopic ultrasound, and additional hormone tests. A c-peptide test is often added when blood sugar problems are part of the picture, and gastrin or chromogranin A may be checked at the same time.
Testing for a vasoactive intestinal peptide antibody is limited to research settings and is not part of the standard workup. If a direct-to-consumer lab offers it, treat the result as experimental rather than diagnostic.
If the level is normal but symptoms continue, the workup shifts toward other causes of chronic diarrhea, including infection, celiac disease, inflammatory bowel disease, bile acid malabsorption, and thyroid problems.
Treatment and Whether You Can Raise VIP Naturally
Treatment depends on the cause, not on the number itself.
- VIPoma: surgery is the main option; when a tumor cannot be removed, somatostatin analogs such as octreotide plus fluid and electrolyte replacement are used.
- Kidney disease: managing the underlying renal problem is the priority.
- Mildly high or normal results with no tumor: no specific treatment is needed.
People also ask how to increase vasoactive intestinal peptide, usually after reading that VIP has anti-inflammatory effects. There is no proven way to raise VIP that produces a clinical benefit, and supplements marketed for "VIP support" have little reliable evidence behind them. Sleep, exercise, and diet influence many gut hormones, but none of those changes replace a proper medical evaluation.
A VIP result is one data point in a larger workup. Any high or low value should be interpreted by an endocrinologist or gastroenterologist alongside your symptoms, medications, and other lab results.
Frequently Asked Questions
What does a high VIP level mean?
A VIP level above roughly 200 pg/mL raises concern for a VIPoma, especially when it comes with large-volume watery diarrhea that continues during fasting. Other possible causes include kidney disease, other neuroendocrine tumors, and problems with how the sample was collected. A single high value is not a diagnosis, so most doctors repeat the test and order imaging.
Do I need to fast for a VIP blood test?
Yes. Most laboratories require an 8- to 12-hour fast because eating stimulates VIP release and can skew the result. Tell your doctor about any medications you take before the draw. Because the sample must be chilled and frozen quickly, testing is usually done at a hospital or specialty draw site.
What is a normal vasoactive intestinal peptide level?
Most labs report a normal fasting VIP level as under 50 to 75 pg/mL. Values between 75 and 200 pg/mL are considered borderline and are usually repeated before any conclusions are drawn. Reference ranges vary by laboratory, so always compare your result to the range printed on your own report.
This page provides educational research information and does not replace medical advice, diagnosis, or treatment.