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Vitamin G (Vitamin K) Activity, Serum

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

This test measures the activity level of vitamin K in your blood, which plays a key role in blood clotting. Low levels may indicate issues with how your body uses vitamin K or potential bleeding disorders.

Quick summary

["Vitamin K helps your blood clot properly; low levels may signal bleeding risks or vitamin K deficiency."]

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

Key facts at a glance

LOINC
109125-5
Short code
VGCC IgG Msmt Ser
Synonyms
VGCC IgG Msmt Ser
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 Is Done

Your healthcare provider may order this test if you have symptoms of bleeding problems, such as excessive bruising, unusual bleeding, or if you’re taking medications that affect blood clotting. It may also be used to monitor vitamin K levels in patients receiving vitamin K therapy, such as those with liver disease or those who’ve had certain surgeries.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for a few hours before the test, but always follow your provider’s instructions. Bring any medications you’re taking, as some can affect blood clotting.

During the Test

A small needle will be inserted into your arm to draw blood. You may feel a slight pinch, but it’s usually over quickly. The blood sample will be sent to a lab for analysis.

After the Test

You can return to your normal activities immediately. Apply gentle pressure to the site to stop any bleeding, and check for signs of infection, such as increased redness or swelling. Avoid heavy lifting or strenuous activity for a short time.

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 activity to be low?
Low vitamin K activity can result from conditions that affect vitamin K absorption (such as bowel diseases), liver problems, certain medications (like blood thinners), or vitamin K deficiency due to poor diet or malabsorption.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the results with you during your follow-up visit.
Can I eat or drink anything before this test?
Follow your provider’s instructions, but generally, you may eat a normal meal unless fasting is required. Avoid alcohol and heavy meals before the test to ensure accurate results.
  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