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Thrombin Time (Activated) with Thrombin Clotting Assay (Plasma)

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

This test measures how long it takes for thrombin to convert fibrinogen into fibrin, helping assess blood clotting function in plasma. It’s often used to monitor anticoagulant therapy or diagnose bleeding disorders.

Quick summary

["Checks how quickly your blood can form clots under controlled conditions."]

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

Key facts at a glance

LOINC
87103-8
Short code
Guided Thromb infus W thromb via CVC
Synonyms
Guided Thromb infus W thromb via CVC
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
imaging-modality
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 This Test Measures

The test evaluates the intrinsic pathway of coagulation by exposing plasma to thrombin. When fibrinogen (a protein needed to form clots) reacts with thrombin, it turns into fibrin, which forms a clot. The time taken to observe this clotting process is recorded. This helps identify issues with clotting factors or anticoagulant medications.

Why It’s Done

Your doctor may order this test if you’re on blood thinners (like warfarin or heparin), have suspected bleeding disorders, or experience unusual clotting problems. It’s also used to monitor treatment effectiveness or diagnose conditions like hemophilia.

How It Works

A small sample of your plasma is mixed with thrombin in a lab setting. A stopwatch measures how long it takes for a clot to form. This time reflects the efficiency of your blood’s natural clotting mechanisms.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about any medications (especially blood thinners) or recent injuries. Avoid eating or drinking for 2–4 hours before testing if instructed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

ACT (Activated Clotting Time)

Frequently asked questions

Why might my results be abnormal?
Prolonged thrombin time could indicate low levels of fibrinogen, inherited clotting disorders (e.g., hemophilia), or excessive anticoagulant use. Shortened times may suggest artificial anticoagulants (like heparin) are too active or a rare clotting disorder exists. Always discuss results with your healthcare provider.
What does a normal result mean?
A normal result suggests your blood clotting factors are functioning as expected, but it doesn’t rule out all clotting issues. Your doctor may order additional tests for diagnosis.
Can I get this test at home?
No, this test requires a blood draw in a clinical lab. Your doctor will schedule it during a routine office visit or lab appointment.
  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