Other analyses
Serotonine
Serotonin in serum, mainly from the platelets; says nothing about serotonin in the brain or about your mood.
Everything about this testWhat it measures
Serotonin is a signaling substance. In the brain it plays a role in mood and sleep, but most of the serotonin in the body is made in the gut wall. In the blood, more than 90 percent of it is in the platelets. This analysis measures serotonin in serum: when the blood clots, the platelets release their serotonin. Serotonin from the brain barely reaches the blood; the value therefore mainly says something about the gut, diet and the platelets.
- The effect of serotonin-rich food, such as banana, pineapple, walnut, tomato and avocado
- The effect of medicines that act on serotonin, especially antidepressants (SSRIs), which strongly lower the serotonin in the platelets
- Rarely: a hormone-producing tumor in the gut or lung (neuroendocrine tumor) that makes a lot of serotonin
High
A raised value is usually caused by food in the days before the blood draw, such as banana, pineapple, walnut, tomato, avocado, plums or melon, or by supplements with 5-HTP or tryptophan. A high platelet count also raises the value. A high value does not mean there is more serotonin in the brain and says nothing about your mood. Rarely: a strongly raised value fits a hormone-producing tumor in the gut or lung (neuroendocrine tumor, formerly called carcinoid); this single measurement is not intended for that, and diagnosis takes place in hospital with other tests.
Low
A low value is most often caused by antidepressants such as SSRIs: they make the platelets take up little serotonin, so the value in blood falls sharply. A low platelet count also lowers the value. A low value does not mean there is a shortage in the brain and is not a sign of depression or a 'serotonin deficiency'.
Preparation
- For 3 days before the sample is taken, do not eat pineapple, eggplant, avocado, bananas, red currants, melon, mirabelle plums, gooseberries, tomatoes, walnuts or plums; they raise serotonin.
- Do not take acetaminophen (paracetamol) or aspirin (acetylsalicylic acid) for 2 days before the sample is taken. If they were prescribed to you, check with your doctor first.
- Taking chlorpromazine or methocarbamol? Do not stop on your own, but mention it when your blood is taken.
If your result is abnormal
With a raised value, the GP first looks at diet, supplements and medicines in the days before the blood draw and, if needed, repeats the test under the right conditions. If the value stays strongly raised, referral to an internist for further testing may follow.
Reliability
Serotonin in blood cannot be used to assess mood, depression, anxiety or sleep: the brain and the blood each have their own serotonin, which barely exchange. According to the Dutch Society for Clinical Chemistry (NVKC), the result depends strongly on diet, age, sex and method, and every laboratory has its own normal values. Outside a specific medical question from a treating doctor, a result is hard to interpret.
Limitations
- Diet: the laboratory asks you not to eat pineapple, eggplant, avocado, banana, red currants, gooseberries, melon, mirabelle plums, plums, tomatoes or walnuts for 3 days before the blood draw.
- Medicines: antidepressants (SSRIs) strongly lower the value. According to the laboratory, chlorpromazine and methocarbamol, among others, affect the measurement, and paracetamol (acetaminophen) and acetylsalicylic acid (aspirin) are advised against for 2 days beforehand. Do not stop a prescribed medicine on your own.
- The blood must be centrifuged immediately after clotting and the serum frozen; if not, the value changes.
- The platelet count partly determines the result.
How common is this
No condition is diagnosed with this single test, so there is no figure for how often an abnormal result means something. Abnormal values due to diet and medicines are common; tumors that make a lot of serotonin are rare.
Who is this useful for
Useful if a treating doctor asks for this test as an addition to other tests. Not useful for assessing mood, depression, anxiety, sleep problems or a supposed serotonin deficiency, or for checking whether antidepressants or supplements work: the value says nothing about that. People who take antidepressants usually have a low value.
Downsides and risks
- An abnormal value due to diet or medicines can cause unnecessary worry and unnecessary follow-up tests.
- The result can wrongly be read as a measure of mood or as a reason to take supplements or change medicines.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results