Vitamin K-dependent clotting factors (prothrombin complex) activity, serum/plasma
This test measures the activity of blood clotting factors that depend on vitamin K, including prothrombin and factors VII, IX, and X. It helps assess how well your blood can clot normally.
["Evaluates vitamin K-dependent clotting function to check for bleeding disorders or liver issues."]
Key facts at a glance
- LOINC
- 75109-9
- Short code
- VLCFA.C22:1n9 EntSub RBC
- Synonyms
- VLCFA.C22:1n9 EntSub RBC
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 4.2
- Ref high
- 5.9
- Critical range
- 2 N/A – 7 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85041
- SNOMED
- 900000000000003001
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why This Test Matters
Your body needs certain proteins (clotting factors) to stop bleeding after an injury. Vitamin K helps make these proteins. If your body doesn’t produce enough, you may bleed more easily or have unusual bruising. This test checks if your blood clotting system is working as it should.
What to Expect Before the Test
No special preparation is needed unless your doctor tells you otherwise. You’ll have a small needle inserted into a vein (usually in your arm) to draw blood. It usually takes about 15 minutes. If you’re on blood thinners, let your doctor know before the test.
Common Causes for Testing
Your doctor might order this test if you have symptoms like easy bruising, excessive bleeding, or if you’ve been diagnosed with liver disease, vitamin K deficiency, or certain blood disorders. It’s also used to monitor treatment for bleeding disorders.
What the Results Mean
Results are compared to a standard range to see if your clotting factors are working properly. A lower-than-normal result may indicate problems with vitamin K, liver function, or blood clotting. Your doctor will discuss the results with you in detail.
Reference range
Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal results can signal conditions like vitamin K deficiency, liver disease, or inherited clotting disorders. High levels might suggest overproduction of clotting factors or certain medications. Always consult your healthcare provider for interpretation.
Short name
VKCF Activity
Frequently asked questions
Will I feel any pain during the blood draw?
Can I eat or drink normally before this test?
How long will it take to get my results?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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