Fibrin and Fibrinogen-Degradation Products

Fibrin and fibrinogen-degradation product (FDP) testing is commonly used to diagnose disseminated intravascular coagulation (DIC).

Normal findings

FDP: < 10 mcg/mL or < 10 mg/L (SI units) ^[1]

Possible critical values

FDP: > 40 mcg/mL ^[1]

Fibrinogen-degradation product (FDP) testing is commonly used to aid in the diagnosis of disseminated intravascular coagulation (DIC).

Increases in serum FDP levels can be caused by the following ^{[2, 3]} :

• DIC

• Post fibrinolytic therapy

• Thromboembolic events

• Pulmonary embolism (peak values may be transient)

• Deep vein thrombosis

• Acute myocardial infarction (first 24-48 h)

• Preeclampsia

• Exercise, anxiety, stress, severe liver disease (mild elevation)

• Acute limb ischemia

• Acute cardiovascular accident

• Acute and chronic renal failure

• Sepsis/shock

• Postoperative states

• Glomerulonephritis

• Extensive tissue damage

Increases in urine FDP levels may be caused by the following:

• Urinary tract infection (increased in upper tract infection but not bladder infection)

• Rejection of renal transplant

Low levels do not have any clinical significance.

See the list below:

• Container - Blue top (citrate) (see image below)

  Blue-top tube.

  View Media Gallery

• Sample volume - 2 mL blood (minimum volume, 1 mL)

• Precautions - Mix by gently inverting; tube agitation may cause RBC hemolysis. ^[2]

• Blood should be collected in a blue top containing 3.2% buffered sodium citrate ^[4] ; evacuated collection tubes must be filled completely to ensure a proper blood-to-anticoagulant ratio in order to yield proper results ^{[5, 6]}

A blood clot is caused by an injury to an artery or vein that activates the coagulation cascade. Fibrin threads are produced during the coagulation process. These fibrin threads form a mesh to clump platelets because they are cross-linked to form blood clots. When the injury heals, the clot is broken down by plasmin for removal. These broken fibrin fragments are called fibrinogen-degradation products (FDPs).

Clot is degraded by plasmin. Plasmin converts fibrinogen initially into X component, which is cleaved into component Y and component D. Component Y is cleaved into component D and component E. Component D is also called D-dimers. Normally undetectable, D-dimer levels are elevated when a clot is broken down. ^[7]

The results of a rapid latex agglutination test kit parallel the results of the hemagglutination inhibition (HAI) method in detecting levels of 10 mcg/mL or higher. These results detect major FDPs but do not differentiate fibrinolysis from fibrinogenolysis. See the images below.

Indications/Applications

It is used to diagnose disseminated intravascular coagulation.

Fibrin split products are used to rule out venous thromboembolism (including deep vein thrombosis and pulmonary embolism). ^[8]

Considerations

False-positives results on fibrinogen degradation product (FDP) testing may be caused by rheumatoid factor.

Chronic conditions (eg, renal failure, liver failure) in elderly persons may cause an increase in FDP levels. Decreased FDP levels do not have clinical significance.