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Platelet Function Test (Platelet Aggregometry)

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

This test measures how well your platelets stick together and clump to form blood clots when needed. It helps assess bleeding risks or issues with clot formation.

Quick summary

["Understanding how your platelets function can help diagnose bleeding disorders or clotting problems."]

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

Key facts at a glance

LOINC
73556-3
Short code
Platelet IgM SerPl Ql FC
Synonyms
Platelet IgM SerPl Ql FC
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
150
Ref high
400
Critical range
50 N/A – 1000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
85049
SNOMED
900000000000003003
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 This Test Matters

Platelets are tiny blood cells that help stop bleeding by sticking together and forming clots. This test checks how effectively they work under different conditions, such as when exposed to certain substances that trigger clotting.

How the Test Works

A small sample of your blood is mixed with special substances in a lab. The test measures how quickly and strongly platelets clump together, which helps identify if they function normally or are impaired.

Common Uses

Doctors may order this test if you have symptoms like easy bruising, excessive bleeding, or unexplained clots. It’s also used before surgeries or procedures that could affect bleeding.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about any medications (like blood thinners) or recent injuries that might affect results.

Reference range

Adult: 150-400 x 10^9/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Platelet Function Test

Frequently asked questions

What causes platelet function tests to be ordered?
Tests are often ordered if you have unexplained bruising, bleeding gums, nosebleeds, or if you’re scheduled for surgery. Doctors may also use it to check for inherited bleeding disorders or to monitor medications that affect clotting.
How long does it take to get results?
Results are typically ready within 1–2 business days, depending on lab processing times. Your doctor will discuss them with you during your follow-up.
Can lifestyle changes affect platelet function test results?
Yes, certain medications (like aspirin, ibuprofen, or blood thinners), alcohol, or infections can influence platelet function. Avoiding these factors before testing may improve accuracy.
  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