Test Details


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Fibrinogen (Factor-I), Sodium Citrate Plasma

Number of parameters covered 2


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Synonyms/Also Known as

Factor I, Fibrinogen Activity, Hypofibrinogenemia Test

Related tests

PT and INR, PTT, D-dimer, Coagulation Factors, Thrombin Time, hs-CRP

Why get tested?

To investigate a person with a bleeding disorder or a blood clot, to assay the levels of fibrinogen (factor 1) and its functions, to assess the risk of developing a heart disease.

When to get tested?

When there are episodes of bleeding or thrombosis, when Prothrombin Test and/or activated partial thromboplastin time test is prolonged, when there is a family history of hereditary fibrinogen deficiency or abnormality, to evaluate the risk of developing heart disease in a person.

Sample required


Test preparation needed

No special preparation required

About The Test

How is it used
Fibrinogen (factor 1) test is used to evaluate fibrinogen levels in the blood. Fibrinogen is a protein essential for blood clot formation. When there is bleeding in response to injury, the body forms a blood clot through several steps to stop the bleeding. One of the last steps is conversion of soluble fibrinogen into insoluble fibrin threads which crosslink together and form a net that will stabilize the clot. A fibrinogen activity test measures the functional capacity of fibrinogen and its ability to get converted into fibrin. A fibrinogen activity test is used as a part of an investigation to diagnose a possible bleeding disorder or formation of an inappropriate blood clot (thrombotic episode). A fibrinogen activity test is used as a follow-up to an abnormal prothrombin time (PT) or activated partial thromboplastin time (aPTT) and/or an episode of prolonged or unexplained bleeding. A fibrinogen activity test is used along with other coagulation tests like prothrombin time (PT) or activated partial thromboplastin time (aPTT), platelet function tests, fibrin degradation products and/or D-dimer to diagnose disseminated intravascular coagulation or abnormal fibrinolysis. A fibrinogen activity test is occasionally used to monitor the status and treatment of a progressive disease (like liver disease) and an acquired condition (such as DIC). A fibrinogen activity test is done along with other cardiac risk markers (C-reactive protein) to determine a person's risk of developing a heart disease. A fibrinogen antigen test is occasionally done as a follow-up test to determine if a decreased fibrinogen activity is due to low levels of fibrinogen or dysfunctional fibrinogen (inherited or acquired dysfibrinogenemia).


1. How can fibrinogen levels be reduced?

If fibrinogen levels are increased due to conditions like pregnancy or acute inflammation, they will return to normal levels, when the underlying condition has been resolved. If fibrinogen concentration is increased due to an acquired condition like rheumatoid arthritis, they remain unaltered. If elevated fibrinogen concentrations are increasing the risk of cardiovascular disease, lifestyle changes (reducing cholesterol and raising HDL) may help.

2. How are fibrinogen, d-dimer, and fibrin degradation products (FDP) tests different?

Fibrinogen activity test is used to evaluate the conversion of soluble fibrinogen into insoluble fibrin in the body. Testing for fibrinogen antigen levels measures the total amount of soluble fibrinogen in the blood. D-dimer and FDP test evaluate the fibrinolytic system. Fibrin degradation products (FDP) measures all the fragments of the dissolving clot, while D-dimer is a more specific test that measures the crosslinked and break-down fragments.

3. Can I have hypo or dysfibrinogenemia and be asymptomatic?

Yes. Many people remain asymptomatic with abnormal or low levels of fibrinogen. Hypo or dysfibrinogenemia may not be identified till a person bleeds for a longer duration than expected, after trauma or a surgery, or when coagulation-related tests are performed.