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Platelet Function Test with Clopidogrel Monitoring (P2Y12 Reaction Time or Inhibition)

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

This test measures how well your platelets respond to clopidogrel, a medication used to prevent blood clots. It helps doctors check if the drug is working properly.

Quick summary

["Assesses whether clopidogrel effectively reduces platelet clumping risk in your blood."]

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

Key facts at a glance

LOINC
73431-9
Short code
Clopidogrel ind plt IgM SerPl Ql FC
Synonyms
Clopidogrel ind plt IgM SerPl Ql FC
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
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 Is Done

Your doctor may order this test if you’re taking clopidogrel (e.g., after a heart attack, stroke, or stent placement) to ensure it’s preventing unnecessary blood clots. It’s also used to monitor treatment response or adjust medication if needed.

What to Expect Before the Test

No special preparation is usually required, but you may need to stop certain medications (like aspirin) for a few days before testing. Your doctor will guide you on timing.

How the Test Works

A small blood sample is taken to measure how platelets clump in response to clopidogrel. This helps assess whether the drug is inhibiting platelet activity as intended.

What the Results Mean

Results indicate whether your platelets are effectively inhibited by clopidogrel, which is critical for preventing clots. Abnormal results may prompt adjustments to your medication.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is vital for patients on antiplatelet therapy, as it directly evaluates the drug’s effectiveness in reducing clot formation. Highly sensitive to clopidogrel’s impact, it helps balance risks of bleeding versus clotting.

Short name

Clopidogrel Platelet Function Test

Frequently asked questions

Will I feel pain or discomfort during the blood draw?
You may feel a slight pinch, but it’s brief. Most people experience minimal discomfort. A small bandage or ice pack can help afterward.
How long will I need to wait for results?
Results are typically available within 1–3 business days, depending on lab processing. Your doctor will discuss them with you.
Can I eat or drink before this test?
Standard fasting rules for blood tests may apply, but your doctor will confirm. Avoid alcohol or aspirin unless instructed otherwise.
  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