Fibrinogen: how to interpret your blood tests? : Current Woman Le MAG

What is fibrinogen?

Fibrinogen: definition. Fibrinogen is a protein – also called "factor I" – that circulates in the blood plasma. Produced by the liver, this protein is essential for the clotting process.

Coagulation, kézako? When a blood vessel is damaged (in case of external or internal bleeding), a coagulation process takes place: several proteins synthesized by the liver – called "coagulation factors" – work together to formation of a blood clot to stop the flow of blood.

Several clotting factors react to make thrombin; thrombin converts fibrinogen to fibrin; fibrin is divided into small filaments which bind to each other (like a net) to seal the vascular breach. Finally, this clot is stabilized by factor XIII – another coagulation protein – and remains in place for 10 to 14 days, the time of healing.

Fibrinogen too low or too high: what can be the causes?

To know. The fibrinogen assay goes through a blood test: the sample is usually taken from the elbow. The normal level of fibrinogen in the blood is between 2 g / L and 4 g / L (grams per liter of blood). In children, it is rather between 1.5 g / L and 3.5 g / L.

The fibrinogen blood test is often associated with the measurement of the prothrombin level (PT), the measurement of the partial thromboplastin time (TCA), a platelet count and / or a dosage of fibrin degradation products (PDF) to assess the speed and quality of the blood clotting process.

Dosage of fibrinogen: in which cases is it prescribed? A fibrinogen blood test may be prescribed in the event of abnormal and / or prolonged bleeding (hemorrhage), in the event of unexplained blood clots (thrombosis), or in the event of suspected coagulation disease.

Fibrinogen too low: what can be the causes? A blood fibrinogen level of less than 2 g / L may reflect:

  • Hepatic insufficiency: this liver disease leads to an abnormally low production of clotting factors – including fibrinogen,
  • Severe malnutrition,
  • A blood clotting disease: 5 out of 10 million people suffer fromafibrinogenemia, a disease which is characterized by a complete absence of fibrinogen (blood level less than 0.2 g / L); rarer still, thehypofibrinogenemia is characterized by a blood fibrinogen level of between 0.2 g / L and 0.8 g / L.
  • Disseminated intravascular coagulation (DIC): this disease causes a low fibrinogen level in the blood, but also thrombocytopenia (platelet blood level less than 150 g / L). It is observed especially in case of obstetric complications (placental abruption, amniotic embolism …) or in case of cancer (adenocarcinomas of the pancreas or prostate …),
  • Taking thrombolytic drugs (streptokinase, urokinase …),
  • Taking anabolic steroids, androgens, barbiturates or sodium valproate,
  • Significant blood transfusions.

Fibrinogen too high: what can be the causes? A blood fibrinogen level higher than 4 g / L may reflect:

  • Myocardial infarction (or heart attack),
  • An inflammatory disease: rheumatoid arthritis, for example,
  • Acute infection: pneumonia, for example,
  • A stroke,
  • Nephrotic syndrome: this kidney disease is characterized by a high fibrinogen level in the blood, but also by proteinuria (presence of proteins in the urine) and hyperlipidemia (an abnormally high level of lipids in the blood).

To know. During pregnancy, the fibrinogen level in the blood is higher; ditto in case of smoking, use of oral contraceptives (pill), treatment with estrogen, or in case of hormonal treatment of menopause.

And also. In case of dysfibrinogenemia, the fibrinogen level in the blood is normal (between 2 and 4 g / L) but the protein does not work properly, which causes coagulation disorders. It is estimated that 1 in 1 million people are affected by this inherited genetic disease which increases the risk of hemorrhage and thrombosis.

Sources:

Canadian Hemophilia Society

Network of Accredited Medical Biology Laboratories (LABAC)

Biron Health

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⋙ Thrombocytopenia: what is a fall in blood platelets?