Disseminated intravascular coagulation laboratory findings: Difference between revisions

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==Overview==
==Overview==
==Laboratory findings==
Although numerous [[blood test]]s are often performed on patients prone to DIC, the important measures are: [[full blood count]] (especially the [[platelet]] count), [[fibrin degradation product]]s or [[D-dimer]] tests (markers of [[fibrinolysis]]), [[bleeding time]] and [[fibrinogen]] levels. Decreased platelets, elevated FDPs or D-dimers, prolonged bleeding time and decreased fibrinogen are markers of DIC. In general;


==Laboratory findings==
* The diagnosis of DIC is suggested when the appropriate clinical picture (hemorrhage and thrombosis with end-organ dysfunction) is accompanied by lab evidence of procoagulant activation, fibrinolytic activation, and inhibitor consumption.
The peripheral smear will reveal schistocytes and RBC (red blood cell) fragments in ~ 50%, and the absence of schistocytes does not rule out DIC. Most patients will have a mild reticulocytosis and leukocytosis, as well as thrombocytopenia with an increased population of young platelets (due to increased destruction and turnover).
* [[Thrombocytopenia]] is an almost universal finding.
* The peripheral smear will reveal schistocytes and RBC (red blood cell) fragments in ~ 50%, and the absence of schistocytes does not rule out DIC. Most patients will have a mild reticulocytosis and leukocytosis, as well as thrombocytopenia with an increased population of young platelets (due to increased destruction and turnover).
Pathologically, early signs include platelet-rich microthrombi, which are then replaced by fibrin-rich microthrombi.
Pathologically, early signs include platelet-rich microthrombi, which are then replaced by fibrin-rich microthrombi.
* Although one would think that the PT and PTT ([[prothrombin]] time and [[partial thromboplastin time]]) should uniformly be elevated in DIC, this is not the case, with up to 50% of patients having normal values (due to higher circulating levels of clotting factors such as factor Xa and thrombin).
* Fibrin and fibrinogen degradation products, however, are elevated in 80 – 100% of patients.
*:* High FDPs, however, are not specific and can be elevated in any state associated with elevated plasmin levels such as PE/DVT (pulmonary embolism/deep vein thrombosis), liver or renal disease, in patients s/p (status post) surgery, and in women on oral contraceptives.
* The [[D-dimer]], however, is specific for the presence of fibrin degradation, and is thought to be more sensitive and specific for DIC.
* Antithrombin levels have become a key test for diagnosing and monitoring therapy in DIC.
*:* With thrombin activation, antithrombin is also activated, forming thrombin – antithrombin complexes --> reduced AT levels.
* The main differential is TTP-HUS (thrombotic thrombocytopenic purpura-hemolytic uremic syndrome), which is associated primarily with thrombocytopenia, and minimal effects on fibrin degradation.
*:* The PT and PTT in TTP – HUS are therefore usually normal, and there is little evidence of fibrinolysis and inhibitor consumption.


==References==
==References==

Revision as of 16:45, 28 August 2012

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Laboratory findings

Although numerous blood tests are often performed on patients prone to DIC, the important measures are: full blood count (especially the platelet count), fibrin degradation products or D-dimer tests (markers of fibrinolysis), bleeding time and fibrinogen levels. Decreased platelets, elevated FDPs or D-dimers, prolonged bleeding time and decreased fibrinogen are markers of DIC. In general;

  • The diagnosis of DIC is suggested when the appropriate clinical picture (hemorrhage and thrombosis with end-organ dysfunction) is accompanied by lab evidence of procoagulant activation, fibrinolytic activation, and inhibitor consumption.
  • Thrombocytopenia is an almost universal finding.
  • The peripheral smear will reveal schistocytes and RBC (red blood cell) fragments in ~ 50%, and the absence of schistocytes does not rule out DIC. Most patients will have a mild reticulocytosis and leukocytosis, as well as thrombocytopenia with an increased population of young platelets (due to increased destruction and turnover).

Pathologically, early signs include platelet-rich microthrombi, which are then replaced by fibrin-rich microthrombi.

  • Although one would think that the PT and PTT (prothrombin time and partial thromboplastin time) should uniformly be elevated in DIC, this is not the case, with up to 50% of patients having normal values (due to higher circulating levels of clotting factors such as factor Xa and thrombin).
  • Fibrin and fibrinogen degradation products, however, are elevated in 80 – 100% of patients.
    • High FDPs, however, are not specific and can be elevated in any state associated with elevated plasmin levels such as PE/DVT (pulmonary embolism/deep vein thrombosis), liver or renal disease, in patients s/p (status post) surgery, and in women on oral contraceptives.
  • The D-dimer, however, is specific for the presence of fibrin degradation, and is thought to be more sensitive and specific for DIC.
  • Antithrombin levels have become a key test for diagnosing and monitoring therapy in DIC.
    • With thrombin activation, antithrombin is also activated, forming thrombin – antithrombin complexes --> reduced AT levels.
  • The main differential is TTP-HUS (thrombotic thrombocytopenic purpura-hemolytic uremic syndrome), which is associated primarily with thrombocytopenia, and minimal effects on fibrin degradation.
    • The PT and PTT in TTP – HUS are therefore usually normal, and there is little evidence of fibrinolysis and inhibitor consumption.

References

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