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5ohindoleacetateprpscnc

Published: August 9, 2026Updated: August 10, 2026

This test measures the level of 5-HIAA, a breakdown product of serotonin, in platelet-rich plasma to help diagnose certain neuroendocrine tumors.

Quick summary

{"5-HIAA is a waste product from serotonin breakdown","This test helps diagnose carcinoid syndrome and neuroendocrine tumors","Certain foods and medications can affect test results","The test uses blood collected in a special tube","Results help doctors monitor treatment effectiveness"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 10, 2026Editorial policy

Key facts at a glance

LOINC
74769-1
Short code
5-HIAA PRP
Synonyms
5OH-indoleacetate PRP-sCnc
Category
chemistry
Sample
plasma
Container
BD Vacutainer EDTA tube (lavender top) or equivalent, specifically processed for platelet rich plasma
Units
N/A
Ref low
50
Ref high
200
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 18 years
Method
High Performance Liquid Chromatography (HPLC) with electrochemical detection or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
CPT
82542
SNOMED
415271002
Specimen volume
5-10 mL of whole blood collected in EDTA tubes
Stability
Process within 2-4 hours of collection. Platelet rich plasma should be separated and frozen at -20°C or below if not analyzed immediately. Stable for up to 30 days at -70°C.
Hemolysis max
50
Lipemia max
100
Icterus max
20
TAT
48–168 hours
Order
routine

What is this test?

The 5-Hydroxyindoleacetate (5-HIAA) test measures how much of this serotonin breakdown product is in your platelet-rich plasma. Serotonin is a hormone and neurotransmitter that helps regulate mood, sleep, and digestion. After your body uses serotonin, it breaks it down into 5-HIAA, which is then excreted in urine.

Why do I need this test?

Your doctor may order this test if they suspect you have carcinoid syndrome, a condition caused by rare tumors called carcinoid tumors that produce excess serotonin. Symptoms may include facial flushing, diarrhea, abdominal pain, and heart problems. This test helps confirm the diagnosis and also monitors how well treatment is working.

How should I prepare?

Before the test, avoid certain foods for 24-48 hours including bananas, pineapples, avocados, tomatoes, and walnuts, as these can affect results. Also inform your doctor about all medications you're taking, as some drugs (like antidepressants, cough medicines, and pain relievers) may interfere with the test. Your doctor will provide specific instructions.

What happens during the test?

A healthcare professional will draw blood from a vein in your arm using a special tube that prevents the blood from clotting quickly. This tube contains a substance that keeps platelets in the plasma, hence 'platelet-rich plasma.' The sample is then sent to a laboratory for analysis.

Reference range

Reference range varies by laboratory method; typically 50-200 nmol/L in platelet rich plasma. Clinical interpretation should be based on laboratory-specific reference intervals.N/A

Specimen: plasma

Patients should avoid serotonin-rich foods (bananas, avocados, pineapples, walnuts, tomatoes, eggplant) for 24-72 hours prior to specimen collection as these can transiently elevate 5-HIAA levels. Avoid aspirin and other platelet-affecting medications for 5-7 days if possible. No fasting required but morning collection recommended.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings2

Frequently asked questions

Is the test painful?
You may feel a brief pinch when the needle is inserted to draw blood. Some people experience minor bruising afterward, but this usually goes away quickly.
How long does it take to get results?
Results are typically available within a few days to a week, depending on the laboratory. Your doctor will contact you with the results or discuss them at your next appointment.
Can I eat normally before the test?
You should follow your doctor's specific instructions about diet. Generally, you should avoid serotonin-rich foods like bananas, pineapples, and avocados for 24-48 hours before the test, as these can falsely elevate results.
What if my results are abnormal?
An abnormal result doesn't always mean you have a serious condition. Your doctor will interpret the results in context with your symptoms, physical exam, and other tests. Additional testing may be needed to confirm a diagnosis.
Will I need to repeat this test?
Your doctor may order repeat testing to monitor your condition if you've been diagnosed with carcinoid syndrome or a neuroendocrine tumor. The frequency depends on your specific situation and treatment plan.
  1. 1
    MedlinePlus - 5-HIAASource
  2. 2
    Mayo Clinic Laboratories - 5-HIAASource
  3. 3
    LOINC Code 74769-1Source

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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 10, 2026. · Read our editorial policy