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Serum or plasma mass concentration of serotonin

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of serotonin, a chemical messenger in your blood, which helps regulate mood, appetite, and sleep. Serotonin is also involved in blood clotting and digestion.

Quick summary

["Serotonin levels can help diagnose or monitor conditions affecting mood, digestion, or blood clotting."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
58878-0
Short code
GH sp29 SerPl-mCnc
Synonyms
GH sp29 SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Might This Test Be Ordered?

Your healthcare provider may order this test if you have symptoms like depression, anxiety, digestive issues (such as irritable bowel syndrome), or bleeding problems. It could also be part of evaluating serotonin syndrome (a rare but serious condition caused by high serotonin levels).

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into a vein in your arm to draw blood. If you’re taking medications that affect serotonin levels (like certain antidepressants), let your provider know.

What the Test Results Mean

Results can vary based on medical conditions, medications, and individual health. High levels may suggest serotonin syndrome or other conditions, while low levels could indicate deficiencies or certain neurological disorders.

Common Conditions Monitored or Diagnosed

Serotonin levels are less commonly used for routine screening but may be checked in cases of suspected serotonin-related disorders, such as serotonin toxicity or rare metabolic conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serotonin Level

Frequently asked questions

What causes serotonin levels to be tested?
Your doctor may order this test if you have symptoms linked to serotonin imbalance, such as mood swings, digestive problems, or unusual bleeding. It could also be part of a broader evaluation for serotonin-related disorders.
How is serotonin tested in the blood?
Blood is drawn from a vein, and the sample is analyzed to measure the amount of serotonin in your serum or plasma using specialized laboratory techniques.
Can serotonin levels be affected by medications?
Yes, certain medications—like selective serotonin reuptake inhibitors (SSRIs) or triptans—can change serotonin levels. Always inform your provider about all medications you’re taking before testing.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy