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Factor Xa Activity (Antithrombin-Coagulation Factor Xa Inhibition)

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

This test measures the activity of Factor Xa, a protein involved in blood clotting, often evaluated in patients with suspected or confirmed coagulation disorders.

Quick summary

["This test helps assess how well your blood clotting system is functioning."]

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

Key facts at a glance

LOINC
3189-8
Short code
Fact IX Ag PPP IA-aCnc
Synonyms
Fact IX Ag PPP IA-aCnc
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
ia
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 healthcare provider may order this test if you have symptoms like excessive bleeding, unusual bruising, or if you’re at risk for blood clots. It can also be used to monitor treatment for conditions like antithrombin deficiency or to check for inherited clotting disorders.

What to Expect Before the Test

You’ll typically have a small needle inserted into a vein (usually in your arm) to draw blood. The process is quick and usually doesn’t cause discomfort. If you’re on anticoagulant medications, inform your provider beforehand.

What the Test Results Mean

Results are compared to a standard range to determine if your Factor Xa activity is within normal limits, lower (indicating potential bleeding risk), or higher (suggesting possible clotting issues). Exact values may vary by lab.

Common Conditions Monitored

This test is often used to diagnose or manage conditions like antithrombin deficiency, factor X deficiency, or to evaluate the effectiveness of anticoagulant therapies.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Factor Xa Activity in Blood Clotting

Short name

Factor Xa Activity

Frequently asked questions

What does a low Factor Xa activity level mean?
A low Factor Xa activity may indicate a bleeding disorder, such as a deficiency in antithrombin or other clotting factors, or could be due to medications that interfere with clotting. Your provider will discuss further steps based on your symptoms and test results.
What does a high Factor Xa activity level suggest?
Elevated Factor Xa activity can sometimes signal an overactive clotting system, though this is less common without additional context. It may be part of a broader evaluation for clotting disorders or hypercoagulable states.
How often should this test be repeated?
Your healthcare provider will determine the frequency based on your medical condition, treatment plan, and symptoms. Regular monitoring may be needed if you’re on long-term anticoagulant therapy or have a known clotting disorder.
  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