Fibrinogen – when we determine the course of the test, deviations from the norm. What does decreased or elevated fibrinogen mean?

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Fibrinogen is a protein involved in the blood clotting process, so its deficiency is associated with the risk of bleeding. Increased fibrinogen levels are also dangerous as they may indicate thrombosis. Find out what role fibrinogen plays in the clotting process and when it should be tested.

Fibrinogen – characteristics

Fibrinogen is a protein that is involved in the final process of blood clotting (therefore it is one of its factors), and its deficiency is associated with the risk of bleeding (impaired clotting). Fibrinogen is produced in the liver and is converted into a fibrin protein (fibrin), which forms a blood clot. His test is used, among others, in the diagnosis of disseminated intravascular coagulation syndrome and in monitoring the treatment of this ailment. Another indication for its determination is the occurrence of prolonged bleeding of unknown origin. Elevated fibrinogen can be dangerous as it can lead to thrombosis.

The clot consists of fibrin, platelets and red blood cells. From the moment you get injured, a clot begins to form within 2 minutes. For this to happen, it must be initiated in the body coagulation cascade. It is a series of reactions involving many clotting factors. Fibrinogen does not appear until the last stage of clotting, when it is converted into fibrin.

Perform a fibrinogen test in parallel with the measurement of other indicators assessed in general health prophylaxis. Choose a comprehensive preventive screening package with home collection, a preventive screening package – blood tests or a test package specifically for men – Preventive blood tests for men.

Fibrinogen – functions

Fibrinogen and blood clotting

Blood clots are extremely important to our health as they stop excessive blood loss and initiate wound healing. In the process of coagulation (clotting), protein threads and cell fragments (platelets) come together to form a hardened clot. This newly formed clot clogs the wound site, preventing further bleeding, while the blood vessel continues to bend and stretch around the wound.

The formation of a blood clot occurs through a series of steps.

During an injury, fibrinogen is cleaved by the enzyme thrombin on the fibrin strands. The XIII enzyme (activated by thrombin) then crosses the fibrin fibers to form a network that, together with platelets, forms a blood clot. The fibrin threads also bind to thrombin to prevent more fibrinogen from being cut open, thus inhibiting the continued formation of clots. Fibrinogen additionally contributes to the formation of clots by binding to receptors on the surface of platelets and binding them together.

Blood clots form when fibrinogen is cut into fibrin fibers that attach to the platelets to form a strong mesh that stops excessive bleeding following an injury.

Fibrinogen and breakdown of blood clots

Fibrinogen and its successor, fibrin, contribute to the breakdown of clots (fibrinolysis).

While fibrin activates plasmin (an enzyme that breaks down clots), fibrinogen inhibits it. These opposing actions ensure that the clots only break down when they are no longer needed. This activity is important because the clots become harmful when they block the blood vessels, leading to heart attack and stroke. The balance of fibrinogen and fibrin in the body prevents the blood from clotting excessively.

See also: When the blood clots too much

Fibrinogen and the immune system

Fibrinogen binds to and activates specific white blood cells (U937, THP-1, Mac-1) in mice and in the laboratory, indicating that it plays a role in the immune response to infection or injury. In another gene association study in 631 sepsis patients, genetic mutations that increased blood fibrinogen levels were correlated with faster recovery and lower mortality.

Similarly, a study in mice with paracetamol-induced liver damage showed that fibrinogen enhances liver repair by activating white blood cells.

Also read: Circulatory system – structure, functions. How does the circulatory system work?

Fibrinogen – when do we perform the test?

The most common study fibrinogen level orders a doctor when a patient has symptoms suggesting a blood clotting disorder. An indication may also be the suspicion of a disease that is associated with an imbalance in the level of this coagulation factor.

The fibrinogen concentration test is performed in the following situations:

1. disorders of the blood clotting process (prolonged bleeding, formation of bruises and wounds after minor injuries);
2. suspicion of an intravascular coagulation syndrome or sepsis involving fibrinogen consumption;
3. liver disease (very rarely);
4. cardiovascular disease risk assessment (including testing for C-reactive protein), however, it is not routine;
5. suspicion of inflammation or a neoplastic process;
6. diagnostics of congenital and acquired bleeding disorders;
7. an auxiliary test in the diagnosis of disseminated intravascular coagulation (DIC) together with the PT, aPTT test, the number of platelets, d-dimers or the test of fibrin degradation products (FDP);
8. coagulation disorders;
9. as a control test to determine whether the low activity of fibrinogen is due to its insufficient amount or the presence of pathological fibrinogen (the so-called dysfibrinogenemia).

Some people may have a fibrinogen test to assess the risk of abnormal bleeding or to schedule treatment with complementary fibrinogen replacement therapy. Routine fibrinogen testing is especially important in pregnant women with a history of abnormal bleeding or pregnancy complications due to abnormal fibrinogen levels.

Some rare genetic diseases can cause changes in the production and function of fibrinogen that can lead to abnormal blood clotting. People with a personal or family history of fibrinogen disorders may undergo testing to confirm the diagnosis and plan treatment.

Also read: Do you have bruises on your body? You may have one of these diseases

Fibrinogen – the course of the study

The concentration of fibrinogen is measured by taking blood from a vein in the arm once, the material for the test is plasma. The patient should be fasting for at least 8 hours prior to the examination. This examination does not require any special preparation, but it is recommended to consult a physician for all medications taken that may affect the coagulation process.

1. Time of waiting for the result: 1 day.
2. Norm: 2-5 g/l.
3. Notes: Fibrinogen belongs to the acute phase proteins, i.e. its concentration increases in the event of an inflammatory process in the body.

The results and standards of fibrinogen may vary from laboratory to laboratory, as does the price of the test, which ranges from PLN 10 to PLN 20.

1. In addition to the concentration of fibrinogen, it is also important to assess its function. It is possible thanks to the study of thrombin time.

Methods for the determination of serum fibrinogen:

1. coagulometry – characterized by adding thrombin to the blood plasma, and then measuring the clotting time (it is inversely proportional to the concentration of the protein tested). Coagulometry is the most commonly used method of testing this protein;
2. Shulz method – it consists in precipitation of fibrinogen at 56 degrees Celsius, and then performing spectrophotometric measurements after transforming fibrinogen into fibrin;
3. Ratnoff-Menzie method – the most accurate and time-consuming test method in which fibrinogen is converted into fibrin and then hydrolysed. The protein level is determined sequentially.
4. immunological measurement – the proteins in the sample are separated by immunoelectrophoresis and fibrinogen is determined with the use of labeled antibodies.

See also: A blood test will show you if you are at risk of having a heart attack or stroke within four years. Important discovery

Testing the concentration of fibrinogen and other tests

A fibrinogen concentration test checks the level of circulating fibrinogen in the blood. Other tests of this type measure various substances that are involved in blood clotting, including:

Prothrombin time / international normalized ratio (PT / INR) is a test that measures the time your blood clots. INR is a calculation based on the results of PT. While PT may be an examination in itself, the INR is often computed along with it.

Partial Thromboplastin Time (PTT) is a test that looks at the time it takes your blood to clot. It can help determine if your blood is having a problem with blood clots forming, but it does not identify the cause of the abnormal clotting. It is also used to measure the effectiveness of anticoagulants.

Thrombin Time (TT) measures the time it takes for fibrinogen to be converted to fibrin by the addition of thrombin, but does not measure the level of circulating fibrinogen in the plasma. It is sensitive to mild fibrinogen deficiency and dysfunction but is affected by other thrombin inhibitory agents such as drugs. The normal TT range is usually from 12 to 14 seconds, with longer times indicating a deficiency of properly functioning fibrinogen.

Fibrinogen – risks associated with the study

The test is simple, quick, and usually has no serious side effects. The blood itself is also not taken for testing.

Occasionally, the patient may feel dizzy or light-headed afterwards. They may also feel a little pain or have a slight bruise at the injection site. Both of these factors are harmless. These symptoms usually disappear within a few days.

In very rare cases, a vein may also become swollen after a blood sample has been drawn. In this case, it may be a good idea to apply a warm compress several times a day. Ongoing bleeding may be a problem if you have a bleeding disorder or if you are taking blood thinners such as warfarin or aspirin.

Another potential complication is infection of the puncture site, manifested by red swelling and possible oozing of pus.

Also read: Blood sampling – when to get tested, what are the rules, how to avoid pain?

Fibrinogen – after the examination

If you have a fibrinogen deficiency, your doctor may prescribe replacement therapy to control or stop bleeding. This is due to the intake of blood products or fibrinogen substitutes through the veins.

This form of treatment should be used to increase the fibrinogen level to 1 gram per liter when there is mild bleeding. In the event of major bleeding or when the patient is undergoing surgery, fibrinogen levels should be increased to 2 grams per liter.

The concentrated form of fibrinogen can also be administered in the following situations:

1. during the procedure;
2. during or after childbirth;
3. before dental surgery;
4. after an accident;
5. to prevent bleeding.

Low fibrinogen – what does it mean?

Reduced fibrinogen (less than 2-5 g / l) may appear in the following situations:

1. cirrhosis,
2. liver failure
3. intravascular coagulation syndrome – DIC,
4. asparaginase treatment,
5. an acquired or congenital defect in fibrinogen biosynthesis.

Chronic reduction of fibrinogen may be caused by inherited low levels of this protein or by malnutrition and end-stage liver failure. In DIC syndrome there is a sharp decrease in fibrinogen. Then, first of all, rapid clotting and consumption of clotting factors occurs, followed by heavy bleeding. It is also worth mentioning that a low concentration of this protein is observed after blood transfusions, as stored blood loses fibrinogen over time.

1. Prothrombin time is a comprehensive test analyzing the activity of blood factors (including fibrinogen).

Elevated fibrinogen – what does it mean?

The increased value of fibrinogen can very often be noticed in various types of infections or infections, because fibrinogen belongs to the acute phase proteins. When does the liver produce more of these proteins? Most often:

1. during inflammation,
2. after burns,
3. after operations,
4. in the course of cancer.

Increased fibrinogen (over> 4g / l) can be observed:

1. in nephrotic syndrome,
2. in diabetics,
3. in smokers,
4. in infections and acute infections,
5. in atherosclerosis,
6. during a heart attack and coronary heart disease,
7. in collagenosis,
8. in Hodgkin’s disease (Hodgkin’s disease),
9. in inflammatory conditions, e.g. RA (rheumatoid arthritis),
10. in the course of a stroke.

Other factors that may affect the increase in fibrinogen include:

1. use of hormone replacement therapy,
2. pregnancy,
3. use of oral hormonal contraception,
4. estrogens.

It should be remembered that fibrinogen is an acute phase protein, so its concentration increases rapidly in the course of inflammation and tissue damage. Its level usually normalizes after the cause has disappeared. High levels of fibrinogen should be treated because high blood clotting is one of the factors of cardiovascular disease. Therefore, the determination of fibrinogen may be performed in conjunction with the examination of other risk factors.

Do you need interpretation of test results? Are you worried about your symptoms? Contact your doctor. Make an online teleconsultation with your family doctor at haloDoctor.pl to get answers to your questions.

How to lower the level of fibrinogen?

If fibrinogen levels are elevated due to pregnancy or acute inflammation, they usually return to normal on their own. If it’s caused by an acquired condition such as rheumatoid arthritis, unfortunately there’s not much that can be done. If doctors believe that elevated fibrinogen levels increase the risk of cardiovascular disease, a patient can make lifestyle changes such as quitting smoking, losing weight, increasing physical activity, lowering cholesterol and raising HDL cholesterol. There is also some evidence that diets high in omega-3 and omega-6 fatty acids (fish oils) can help lower fibrinogen levels.

See also: How to quit smoking Step by step plan [WE EXPLAIN]

Fibrinogen – diseases

Fibrinogen levels are associated with diseases and conditions such as afibrinogenemia, dysfibrinogenemia and renal amyloidosis.

1. Dysfibrynogenemia

People with dysfibrinogenemia have normal levels of fibrinogen but have structural abnormalities that prevent the molecule from functioning properly. Interestingly, about 55% of people with this disorder are asymptomatic, 25% suffer from excessive bleeding, and the remaining 20% ​​have excessive clotting. Other symptoms include delayed wound healing, arterial blood clots, pregnancy complications, and skin necrosis (tissue death).

Congenital dysfibrinogenemia is typically autosomal dominant, meaning that only one parent needs to have the condition for a child to inherit it. Affected people are usually diagnosed as adults, possibly after passing the disease on to their children. For this reason, and because of the high proportion of asymptomatic vectors, scientists suggest that it may affect up to one in 100 people.

Although dysfibrinogenemia is usually caused by hereditary mutations, there have been rare cases of acquired dysfibrinogenemia.

1. Afibrynogenemia

Afibrinogenemia is a rare and usually autosomal recessive disorder in which blood fails to clot due to a lack of fibrinogen (usually plasma fibrinogen levels), but is sometimes detected at extremely low levels, e.g. <10 mg / dL. This serious disorder is usually caused by mutations in both the maternal and paternal copies of the FGA, FGB, or FBG gene. Pathological bleeding occurs early in life, for example it is often seen after birth with excessive umbilical hemorrhage.

1. Hereditary kidney amyloidosis

Hereditary kidney amyloidosis describes a harmful build-up of proteins (amyloid fibers) in the kidneys, which can lead to kidney failure and death. Hereditary renal amyloidosis is caused by various hereditary mutations (including a mutation in the Aα amino acid chain of fibrinogen).

1. Hipofibrynogenemia

Congenital hypofibrinogenemia is a rare inherited disease in which the blood may not clot normally due to decreased levels of fibrinogen (plasma fibrinogen usually <150 but> 50 mg / dL). The disorder reflects a destructive mutation in only one of the two parent FGA genes, FGB or FBG, and has a low degree of genetic penetration, i.e. only some family members with the defective gene ever show symptoms. Symptoms of the disorder, which are more common in people with lower plasma levels of fibrinogen, include episodic bleeding and thrombosis, which usually begin in late childhood or adulthood.

1. Kriofibrynogenemia

Cryofibrinogenemia is an acquired disorder in which fibrinogen precipitates at low temperatures and can lead to intravascular precipitation of fibrinogen, fibrin and other circulating proteins, thereby causing infarction of various tissues and extremities of the body. Cryoglobulonaemia can occur without symptoms of a concomitant disease, i.e. primary cryoglobulinemia or, more commonly, with symptoms of an underlying disease i.e. secondary cryoglobulemia. Secondary cryofibrinenia may develop in people with infection (approx. 12% of cases), cancer or pre-cancerous diseases (21%), vasculitis (25%) and autoimmune diseases (42%). In such cases, cryofibinogenema may or may not cause tissue damage and / or other symptoms, and the actual causal relationship between these diseases and the development of cryofibrinogenemia is unclear. Cryofibrinogenemia can also occur in connection with the intake of certain medications.