Written according to the highest scientific standards and checked by experts
Serotonin is a messenger substance in the human body that has many important tasks. When the value in the blood or urine is determined, normal values and what a serotonin value that is too high or too low means.
Also known as the happiness hormone: Serotonin is a neurotransmitter in the nervous system. In laboratory tests, it is called 5-hydroxy-tryptamine (5-HT). A metabolic product, 5-hydroxyindolylacetic acid (5-HIES), is measured in the blood in a laboratory test.
Article content at a glance:
Blood count: important values and what they mean
What is serotonin?
The messenger substance serotonin transmits information from nerve cell to nerve cell in the human body. It is therefore found in the entire nervous system, and serotonin also has an effect on thrombocytes (blood platelets) and in cells of the intestine. In the brain, serotonin influences the following processes:
- Body temperature
- Reward system
- Mood and drive
- State of consciousness and sleep-wake rhythm
- Pain assessment
In addition, serotonin is involved in other processes in the body:
- Widening and narrowing of the blood vessels
- Dilatation and constriction of the bronchi
- Blood clotting: Serotonin stimulates blood platelets
- Bowel movements
When is the serotonin level determined?
Contrary to the common assumption that the serotonin value could say something about depression, for example, this is not the case. The measurement of 5-HIES in the blood does not allow any conclusions to be drawn about the amount of serotonin in the brain. This would require an examination of the spinal cord fluid, a so-called liquor puncture.
Serotonin (5-HIES) is determined in the blood when a carcinoid is suspected. A carcinoid is a neuroendocrine tumor that usually forms in the gastrointestinal tract and produces excessive serotonin. Typical symptoms are diarrhea and flushed face.
Serotonin normal values (5-HIES)
The normal values of the breakdown product 5-HIES of serotonin are determined either via a blood sample or a 24-hour urine collection.
The reference ranges for normal values of serotonin are:
- in the blood: 50–200 µg / l or 250–800 µg / 1012th Platelets
- in the urine: <200 µg / d
The standard values can vary depending on the method used and the laboratory.
Food and drugs affect serotonin
Since various foods, luxury foods and also drugs influence the serotonin level, it should be avoided two to three days before the blood sample is taken:
Exemplary drugs that can cause falsely high serotonin levels:
Exemplary Drugs That May Cause Falsely Low Serotonin Levels:
What does a serotonin level that is too low mean?
Even if it seems reasonable to assume that a serotonin level that is too low could indicate depression or anxiety disorders, this is not the case. Clinically, i.e. from the disease point of view, a level that is too low is not important.
Meaning of increased serotonin levels
If the serotonin level is significantly increased, this is an indication of a carcinoid. Elevated values can also occur in epilepsy and celiac disease. If a carcinoid is suspected, further investigations will follow.
Good mood: 22 foods for a bad mood
Do you have a question?
Would you like information on specific symptoms or medical advice? Here you can ask your questions to our experts or other Lifeline users!