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Thrombin Time (Activated Clotting Time, ACT) with Peak Measurement

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

This test measures how long it takes for your blood to clot after thrombin is added, including tracking the peak clotting activity. It helps assess blood clotting function and detect abnormalities in coagulation pathways.

Quick summary

["Evaluates blood clotting efficiency and potential clotting disorders."]

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

Key facts at a glance

LOINC
97912-0
Short code
Thrombin peak sub PPP Qn Chro
Synonyms
Thrombin peak sub PPP Qn Chro
Category
chemistry
Sample
plasma
Container
Lavender-top (EDTA) or Green-top (Heparin)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
chromo
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

What Is This Test Measuring?

The test involves mixing a small amount of your blood with a special solution containing thrombin. The time it takes for the blood to form a clot is recorded, and the peak clotting activity is tracked. This helps identify how effectively your blood can stop bleeding and whether clotting factors are functioning properly.

Why Might Your Doctor Order This Test?

Your doctor may request this test if you have symptoms of bleeding disorders (like excessive bruising or nosebleeds), if you’re scheduled for surgery or a procedure that could disrupt your blood, or if you have conditions like liver disease or blood clotting disorders. It can also be used to monitor treatments for clotting issues.

How Is the Sample Collected?

A small blood sample is drawn from a vein, usually in your arm. The blood is placed in a test tube and mixed with a thrombin solution. The clotting process is monitored to measure the time and peak activity.

What Does the Result Mean?

Results are compared to standard benchmarks, but exact ranges can vary by lab. Prolonged clotting times may indicate bleeding disorders, while abnormal peaks could suggest clotting issues. Your doctor will interpret results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance:

Short name

ACT Peak Time

Frequently asked questions

How long does it take for the blood to clot after the thrombin is added?
The time and peak clotting activity help identify whether your blood’s clotting process is functioning normally. For example, prolonged clotting times may signal deficiencies in clotting factors, while irregular peaks could indicate inherited or acquired bleeding disorders. This test is critical for diagnosing conditions like hemophilia or von Willebrand disease, as well as monitoring anticoagulant treatments.
What are the typical reference ranges for this test?
There is no single standard reference range for peak thrombin activity because it depends on the lab’s methods and patient-specific factors. Your doctor will use the results alongside clinical findings to guide diagnosis and treatment.
Can this test be affected by medications I’m taking?
Yes, certain medications—such as blood thinners (e.g., warfarin, heparin) or anti-inflammatory drugs—can alter clotting times. Always inform your healthcare provider about all medications, supplements, or recent treatments 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