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Real-Time Prothrombin Time (PT) with Thrombin

Published: August 9, 2026Updated: August 17, 2026

This test measures how quickly your blood clots in response to a specific blood-clotting protein (prothrombin). It helps assess your risk of bleeding or clotting disorders.

Quick summary

["Helps check blood clotting function and identify bleeding or clotting risks."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
3242-5
Short code
Recal time PPP
Synonyms
Recal time PPP
Category
chemistry
Sample
plasma
Container
Lavender-top (EDTA) or Green-top (Heparin)
Units
N/A
Ref low
7
Ref high
56
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
coag-calcium-ion-induced
CPT
84484
SNOMED
302773008
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 Measured?

The test evaluates the time it takes for blood to clot when exposed to a synthetic thromboplastin (tissue factor) and calcium. This reflects the activity of clotting factors like prothrombin, factor VII, and others in your blood plasma.

Why Is This Test Done?

Real-Time PT is often used before surgery, to manage anticoagulant medications (like warfarin), or to diagnose bleeding disorders. It’s also part of routine monitoring for patients with liver disease or clotting disorders.

How Is the Sample Collected?

A small blood sample is drawn from a vein, usually in your arm. The blood is mixed with a special reagent to simulate natural clotting conditions, and the time to clot is measured in seconds.

What Does the Result Mean?

Results are compared to a standard range to determine if your clotting time is slower (higher risk of bleeding) or faster (higher risk of clotting). Exact values depend on the lab’s reference range and reagent used.

Reference range

Adult males: 7-56 U/L; Adult females: 7-43 U/LN/A

Specimen: plasma

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Real-Time PT

Frequently asked questions

How long does it take for results to be available?
Results are typically available within minutes to hours, depending on the lab’s processing speed. Your healthcare provider will discuss the results with you.
Can I eat or drink before this test?
For most Real-Time PT tests, you can eat and drink normally unless instructed otherwise by your doctor. However, if you’re on anticoagulants, follow your provider’s specific guidelines.
What if my results are abnormal?
If your results are outside the expected range, your doctor may recommend further testing, adjustments to medications, or additional evaluation to identify the cause, such as liver disease, vitamin deficiencies, or clotting disorders.
  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 17, 2026. · Read our editorial policy