5-HT level; 5-hydroxytryptamine level; Serotonin test
The serotonin test measures the level of serotonin in the blood.
The serotonin test measures the level of serotonin in the blood. Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
How the Test is Performed
A blood sample is needed.
How to Prepare for the Test
No special preparation is needed.
How the Test will Feel
When the needle is inserted to draw blood, some people feel slight pain. Others feel a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
Serotonin is a chemical produced by nerve cells.
This test may be done to diagnose carcinoid syndrome. Carcinoid syndrome is a group of symptoms associated with carcinoid tumors. These are tumors of the small intestine, colon, appendix, and bronchial tubes in the lungs. People with carcinoid syndrome often have high levels of serotonin in the blood.
Normal Results
The normal range is 101 to 283 ng/mL.
Note: Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.
What Abnormal Results Mean
A higher-than-normal level may indicate carcinoid syndrome.
Risks
There is very little risk in having your blood taken. Veins and arteries vary in size from one person 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 may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
FAQ
What is a normal serotonin serum level?
- Generally, the normal range for serotonin levels in your blood is 101–283 nanograms per milliliter (ng/mL). This benchmark, however, may differ slightly depending on the measurements and samples tested, so talk to your doctor about specific test results. High levels of serotonin may be a sign of carcinoid syndrome.
What does low serum serotonin mean?
- People who feel unusually irritable or down for no apparent reason may have low serotonin levels. Depression: Feelings of sadness, hopelessness, and anger, as well as chronic fatigue and thoughts of suicide, may indicate depression. Anxiety: Low serotonin levels may cause anxiety.
What is a serotonin blood test called?
- The main test for carcinoid syndrome measures a substance called 5-HIAA in the urine. When a tumor makes serotonin, your body turns it into 5-HIAA. This test may require collecting all the urine you make over a 24-hour period. Another test measures a substance called chromogranin A in your blood.
Can you test for serotonin levels?
- No single test can confirm a serotonin syndrome diagnosis. Your doctor will diagnose the condition by ruling out other possibilities. Your doctor will likely begin by asking about your symptoms, medical history, and any medications you’re taking. Your doctor will also conduct a physical examination.
What are the signs of low serotonin levels?
Some common signs of serotonin deficiency include: