Fibrinogen Test

What is a fibrinogen test?

A fibrinogen test measures your levels of a blood protein called fibrinogen. Fibrinogen is made in your liver and helps your blood clot.

Low fibrinogen may make it difficult for your blood to clot. If you have symptoms of excessive bleeding, your healthcare provider may order this test to check your fibrinogen levels. Another name for a fibrinogen test is a factor I activity test.

When is a fibrinogen test performed?

Your healthcare provider may perform a fibrinogen test if you have symptoms that could point to low fibrinogen, such as:

• Bleeding gums.
• Bleeding in your gastrointestinal (GI) tract.
• Blood in your urine (pee) or stool (poop).
• Coughing up blood.
• Excessive bruising.
• Frequent nosebleeds.
• Ruptured spleen.

You may also have a fibrinogen test if you have:

• Atypical coagulation results like an abnormal prothrombin time test (PT) or activated partial thromboplastin time (APTT), which measures how quickly your blood clots.
• Signs of blood clotting disorders.
• Signs of disseminated intravascular coagulation, a severe clotting disorder.
• Signs of genetic disorders that affect blood clotting.
• Recurrent pregnancy loss.

What are the types of fibrinogen deficiency?

Fibrinogen tests may detect a fibrinogen deficiency. Fibrinogen deficiencies may be genetic, meaning they occur because of a gene change (mutation). They may also be hereditary, meaning your parents pass down the gene mutation to you.

There are a few types of fibrinogen deficiencies:

• Afibrinogenemia, when you have no fibrinogen in your blood. This disorder is extremely rare, affecting only 1 out of every 1 million people.
• Hypofibrinogenemia, when you have low fibrinogen levels. Experts don’t know exactly how many people have hypofibrinogenemia, but it’s more common than afibrinogenemia.
• Dysfibrinogenemia, when you have typical fibrinogen levels, but fibrinogen doesn’t function properly. Similar to hypofibrinogenemia, it’s difficult to estimate the number of people with dysfibrinogenemia because there are a large number of people without symptoms. But it’s more common than afibrinogenemia.

How do I prepare for a fibrinogen test?

Your health care provider will give you specific instructions to prepare for a fibrinogen test. Most people don’t need to do anything different than usual. If you take blood thinners, your provider may instruct you to stop them for a brief period before the test.

Drinking plenty of water can make the test go more smoothly. Staying hydrated keeps more fluid in your veins, making it easier to get a blood sample.

What can I expect during a fibrinogen test?

During a fibrinogen test, your health care provider:

1. Cleans a small area of your arm with rubbing alcohol.
2. Inserts a needle into your arm vein.
3. Attaches the needle to a small tube to collect a blood sample.
4. Removes the needle and covers the area with a gauze pad.

What can I expect after a fibrinogen test?

You can return home and resume your usual activities immediately after the test.

What are the risks of a fibrinogen test?

There are few risks associated with fibrinogen tests. You may have mild bruising or discomfort where the needle was inserted into your arm. These symptoms usually go away within a day or two.