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Vitamin G (Vitamin K) Activity, Serum/Plasma

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

This test measures the level of Vitamin K in your blood, which helps your body make certain proteins needed for blood clotting.

Quick summary

["Vitamin K supports healthy blood clotting and bone health; low levels may indicate bleeding disorders or malabsorption issues."]

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

Key facts at a glance

LOINC
41261-9
Short code
VGCC IgG Ser Ql
Synonyms
VGCC IgG Ser Ql
Category
electrolyte
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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 Might Be Ordered

Your doctor may recommend this test if you have symptoms like easy bruising, excessive bleeding, or unexplained bleeding gums. It could also be checked before surgery to ensure proper clotting function, or if you have conditions like liver disease or intestinal disorders that may affect Vitamin K absorption.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for a few hours before the blood draw. Avoid taking Vitamin K supplements or certain medications (like anticoagulants) as directed by your healthcare provider.

How the Test Works

A small amount of blood is drawn from a vein in your arm. The sample is sent to a lab where it is analyzed to measure Vitamin K activity, often through a clotting assay that checks how well your blood clots normally.

What the Results Mean

Results are typically reported as a ratio or index comparing your blood clotting time to a standard. Low levels may suggest Vitamin K deficiency, while high levels could indicate overuse of Vitamin K supplements or certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin K Activity

Frequently asked questions

What causes Vitamin K deficiency?
Vitamin K deficiency can result from poor diet (low intake of green leafy vegetables), intestinal disorders that impair absorption, long-term use of certain antibiotics, or liver disease. Rarely, it can occur in newborns if they don’t receive Vitamin K shot at birth.
How is Vitamin K deficiency treated?
Treatment often involves Vitamin K supplements (oral or injected) to restore normal levels. Lifestyle changes, such as eating Vitamin K-rich foods, may also help. Your doctor may adjust medications if Vitamin K affects their effectiveness.
Can Vitamin K levels change with diet?
Yes, diet plays a key role. Foods like leafy greens, broccoli, and Brussels sprouts are natural sources of Vitamin K. However, excessive intake of supplements or certain medications can also alter levels, so follow your doctor’s guidance.
  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