Fibrinogen Degradation products (FDP) or Fibrin split products (FSP), and d-Dimer
- It is done in the serum.
- Collect 2 ml blood in a test tube containing Thrombin, soybean, and Trypsin inhibitor.
- Allow to clot at 37 °C for 30 min.
- OR Collect blood with 1:20 dilution (ESR solution 0.2 ml and 1.8 ml blood).
- For d-Dimer plasma (citrate) is stable for 8 hours at room temperature.
Purpose of the test (Indications)
- This test is done to establish the diagnosis of DIC (Disseminated intravascular coagulopathy).
- Thromboembolic disorders like pulmonary embolism.
- This is a screening test for DVT (Deep vein thrombosis).
- It can be used to determine the duration of anticoagulation treatment of DVT.
- Keep in mind that menstruation may be associated with increased FDP value.
- Keep in mind that drugs like barbiturates, streptokinase, urokinase, and heparin may increase the value.
- Some drugs like warfarin and other oral anticoagulants decrease the value.
- Avoid the excessive agitation of the blood.
- Avoid prolonged use of a tourniquet.
- The normal homeostasis is a balanced interaction of the vascular endothelium, platelets, and four biochemical systems.
- FDPs generates when there is inappropriate clotting seen in disseminated intravascular coagulopathy (DIC).
- The trigger for this excessive intravascular coagulopathy may be:
- Severe trauma.
- Amniotic fluid embolism.
- Premature separation of the placenta.
- Mucinous Adenocarcinoma.
- Liver diseases.
- Acute myelocytic leukemia.
- Falciparum malaria.
- Snake Bites.
- All the above factors lead to the release of procoagulants and give rise to platelets aggregation.
- Gram-negative and meningococcal septicemia, septic abortion, and viral diseases lead to endothelial injury and cause intravascular clot formation.
- Fibrinogen degrades products (FDP) are polypeptide fragments that are generated by the enzymes when the body tries to dissolve blood clots.
- These fibrinogen degradation products are named X, Y, D, and E, and collectively called fibrinogen degradation products (FDP).
- These FDPs have anticoagulant action.
- FDP is the substances that remain in the blood after the blood clot is dissolved.
- Fibrin is split by Plasmin and form fibrin degradation products, and d-Dimer.
- The FDP has an anticoagulant action and inhibits clotting when these are present in excess.
- FDP and d-Dimer correlate with each other and are evidence for DIC or another intravascular thrombosis.
- FDP and d-Dimer assess both thrombin and plasmin activity.
- The d-Dimer assay provides a highly specific measurement of fibrin degradation that occurs.
- Normal plasma has no detectable d-Dimer.
Symptoms of DIC:
- There may Nausea and vomiting.
- The patient may have bleeding from the gums.
- There is severe muscular pain.
- There may be abdominal pain.
- The patient will have reduced urinary output (oliguria) and hematuria.
- There is dyspnea.
- Ultimately shock and confusion.
Drugs affecting the FDP level:
- Some of the drugs may affect and increase the level of FDP in the like:
- When heparin was given to treat the blood clots.
- When streptokinase is given in patients with coronary thrombosis.
- Barbiturates may increase the FDP level.
- Treatment by the urokinase to dissolve the clot.
- FDP = <10 µg/mL
- To convert to SI unit x 1.0 = <10 mg/L
- FDP = Negative at 1:4 Dil.
- Quantitative value is <10 µg /ml or <10 mg/L.
- d-Dimer is more specific than FDP.
- Negative = No d-Dimer fragments are found in plasma.
- <0.25 mg/L (or <0.4 µg/mL).
- Negative, no d-dimer fragments are found.
- <250 ng/mL (<250 µg/L)
- When both test d-Dimer and FDP are done are more specific for the diagnosis of DIC.
Increased FDP or d-Dimer level is seen in:
- Pregnancy ( abruptio placentae, Eclampsia, retained dead fetus, and sepsis ).
- Myocardial infarction.
- Heart or vascular surgery.
- Pulmonary embolism.
- Thrombolytic or defibrination therapy.
- Primary and secondary fibrinolysis.
- in the case of DIC.
- Venous thrombosis (Deep vein thrombosis, DVT).
- Liver disease.
- Allograft rejection.
- Sickle cell anemia.
- Massive trauma.
Decreased FDP value seen in:
- Anticoagulant therapy.
Critical Value of FDP is above >40 µg/mL or 40 mg/L