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Fibrinogen (Fibrinogen Level) by Clotting Time (Merz Index-Based)

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

This test measures the amount of fibrinogen in your blood, a protein essential for blood clotting. It helps assess your risk of bleeding or clotting disorders.

Quick summary

["Fibrinogen levels can indicate bleeding or clotting risks and are often checked alongside other coagulation tests."]

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

Key facts at a glance

LOINC
11918-0
Short code
GA from Fib Length.Merz.87
Synonyms
GA from Fib Length.Merz.87
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-estimated-from-fibula-length-merz
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 doctor may order this test if you have symptoms of bleeding problems (like excessive bruising or nosebleeds), clotting issues (like unexplained blood clots), or if you’re undergoing surgery or a medical procedure. It can also be part of routine blood work to monitor conditions like liver disease or certain blood disorders.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on blood thinners, let your doctor know before the test to avoid unnecessary delays or adjustments.

What the Test Results Mean

Fibrinogen levels vary by health, age, and other factors. While reference ranges differ by lab, low levels may suggest bleeding disorders, and high levels could indicate inflammation or liver disease. Your doctor will interpret results in the context of your overall health.

Common Conditions Monitored

This test helps diagnose or manage bleeding disorders (like hemophilia), clotting disorders (like disseminated intravascular coagulation), liver disease, or inflammatory conditions. It’s also used to guide treatment decisions for patients on anticoagulants.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Fibrinogen Level

Frequently asked questions

How long does it take to get my test results?
Results are typically available within 1–3 business days, depending on your lab. Follow up with your doctor to discuss findings and next steps.
Can I eat or drink before this test?
You can eat and drink normally unless instructed otherwise. Avoid alcohol for 24 hours before testing if your doctor recommends it.
What if my fibrinogen level is outside the normal range?
If your results are abnormal, your doctor may recommend further testing or treatments, such as blood transfusions for low levels or medications to manage clotting risks. Always discuss findings with your healthcare provider.
  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