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Fibrinogen concentration (serum/plasma)

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

This test measures the amount of fibrinogen, a protein in your blood that helps blood clot.

Quick summary

["Fibrinogen helps your body stop bleeding and supports blood vessel repair."]

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

Key facts at a glance

LOINC
100994-3
Short code
B19B20
Synonyms
Bld FC
Category
chemistry
Sample
serum
Container
EDTA (lavender/purple-top) anticoagulant tube for whole blood flow cytometry
Units
N/A
Ref low
5
Ref high
15
Fasting
false
Population
adult
Sex
all
Age range
≥ 0 years
Method
flow-cytometry
CPT
86356 (each marker); 88184 (flow cytometry, cell surface, cytoplasmic); 88185 (additional marker)
SNOMED
42954000 | 116647005
Specimen volume
3-5 mL of whole blood; minimum 1 mL for pediatric patients
Stability
Specimen must be processed within 24-48 hours of collection when stored at room temperature (18-25°C). Do not refrigerate or freeze. Analysis ideally performed within 24 hours.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

Why Might You Need This Test?

Your doctor may order a fibrinogen test to check for bleeding disorders, clotting problems, or conditions like liver disease, which can affect protein production in your blood. It may also be used during pregnancy to monitor clotting risks or after surgery to ensure proper healing.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it involves drawing blood from your arm. Tell your doctor about any medications or supplements you take, as some may influence results.

How the Test Works

Blood is drawn from a vein in your arm and sent to a lab. The lab measures fibrinogen levels using a method called nephelometry, which detects how much protein is present in your blood sample.

What the Results Mean

Results are reported as a concentration value (e.g., grams per deciliter). Low levels may suggest bleeding disorders or liver issues, while very high levels could indicate inflammation or certain blood disorders. Your doctor will interpret results in the context of your overall health.

Reference range

CD19+ B-cells: 5-15% of total lymphocytes (absolute count: 107-516 cells/μL); CD20+ B-cells: 5-15% of total lymphocytes (absolute count: 107-516 cells/μL). Reference ranges vary by age and laboratory.N/A

Specimen: serum

No special patient preparation required. Fasting is not required. Inform the laboratory of any recent immunosuppressive therapy, monoclonal antibody treatment (e.g., rituximab), or chemotherapy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Fibrinogen is crucial for blood clotting and wound healing. Abnormal levels can indicate underlying health conditions, such as von Willebrand disease (a bleeding disorder), disseminated intravascular coagulation (DIC), or liver disease. Doctors may also monitor fibrinogen during treatments for cancer, infections, or after major surgeries to prevent excessive bleeding or clotting.

Short name

Fibrinogen

Frequently asked questions

What causes low fibrinogen levels?
Low fibrinogen can result from liver disease (where the body can’t produce enough protein), severe infections, pregnancy, or certain medications. It may also occur in conditions like DIC or bleeding disorders.
What causes high fibrinogen levels?
High fibrinogen is often linked to inflammation (e.g., infections, autoimmune diseases), cancer, or pregnancy. Rarely, it may be genetic or due to overactive thyroid function.
Can diet affect fibrinogen test results?
Dietary factors typically don’t significantly impact fibrinogen levels, but avoiding alcohol or certain medications (like blood thinners) before testing can help 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