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Factor VIII Activity (Plasma)

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

This test measures how well your blood can clot by checking the level of Factor VIII, a protein essential for blood clotting. Low levels may increase bleeding risk.

Quick summary

["Factor VIII helps prevent excessive bleeding by aiding clot formation."]

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

Key facts at a glance

LOINC
3205-2
Short code
Fact VIII Ab PPP IA-aCnc
Synonyms
Fact VIII Ab 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 Is This Test Done?

Your doctor may order this test if you have a history of easy bruising, excessive bleeding (e.g., nosebleeds, heavy menstrual periods), or if you’re planning surgery. It’s also used to monitor treatment for hemophilia or von Willebrand disease.

What Does a Low or High Level Mean?

Low Factor VIII levels may indicate bleeding disorders like hemophilia or von Willebrand disease. High levels are less common but could be due to certain medications or inherited conditions.

Sample Collection and Preparation

Blood is drawn from a vein (usually in your arm) into a special tube to separate plasma. This test requires fresh plasma and is typically done within 2 hours of collection.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about any medications (especially blood thinners) or recent illnesses that might affect results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Factor VIII Coagulation Factor

Frequently asked questions

Will I feel pain during the blood draw?
You may feel a slight pinch or discomfort when the needle is inserted, but most people tolerate it well. A bandage will cover the site afterward.
How long will results take?
Results are usually 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?
You can eat and drink normally unless instructed otherwise. No fasting is required.
  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