|Values are valid only on day of printing.|
Detection of the more common potential causes of abnormal bleeding (eg, factor deficiencies/hemophilia, von Willebrand disease, factor-specific inhibitors) and a simple screen to evaluate for an inhibitor or severe deficiency of factor XIII (rare).
Initial testing includes: prothrombin time (PT), activated partial thromboplastin time, thrombin time (bovine), fibrinogen, D-dimer, soluble fibrin monomer, coagulation factor VIII activity assay, von Willebrand factor antigen, von Willebrand factor activity, factor XIII screen, and special coagulation interpretation.
If PT is > or =14 seconds, PT mix will be performed.
If APTT is >36 seconds, APTT mix and DRVVT will be performed.
If DRVVT ratio is > or =1.2, DRVVT mix will be performed.
If DRVVT mix ratio is > or =1.2, DRVVT confirmation will be performed
If APTT mix is >36 seconds with no evidence of heparin in samples, platelet neutralization procedure will be performed.
If thrombin time is >23 seconds, reptilase time will be performed.
If von Willebrand factor activity assay is <55%, von Willebrand factor ristocetin cofactor activity assay will be performed.
If von Willebrand factor (VWF) antigen is <55%, the VWF activity is <55%, or the VWF activity:VWF antigen ratio is <0.8, VWF multimer analysis will be performed.
If appropriate, coagulation factor assays or Staclot LA will be performed at an additional charge to clarify significant abnormalities in the screening clotting times.
If factor VIII result is <55%, the factor VIII inhibitor screen may be performed along with the Bethesda titering assay, if inhibitor screen is positive.
See Hemophilia Testing Algorithm in Special Instructions.
Bleeding problems may be associated with a wide variety of coagulation abnormalities or may be due to problems not associated with coagulation (trauma and surgery as obvious examples). A partial listing of causes follows.
-Deficiency or functional abnormality (congenital or acquired) of any of the following coagulation proteins: fibrinogen (factor I), factor II (prothrombin), factor V, factor VII, factor VIII (hemophilia A), factor IX (hemophilia B), factor X, factor XI (hemophilia C; bleeding severity not always proportionate to factor level), factor XIII (fibrin-stabilizing factor), von Willebrand factor (VWF antigen and activity), and alpha-2 plasmin inhibitor and plasminogen activator inhibitor (PAI-I; severe deficiency in rare cases). Neither alpha-2 plasmin inhibitor nor PAI-I are included as a routine bleeding diathesis assay component, but either can be performed if indicated or requested.
-Deficiency (thrombocytopenia) or functional abnormality of platelets such as congenital (Glanzmann thrombasthenia, Bernard-Soulier syndrome, storage pool disorders, etc) and acquired (myeloproliferative disorders, uremia, drugs, etc) disorders. Platelet function abnormalities cannot be studied on mailed-in specimens.
-Specific factor inhibitors (most commonly directed against factor VIII); factor inhibitors occur in 10% to15% of the hemophilia population and are more commonly associated with severe deficiencies of factor VIII or IX (antigen <1%). The inhibitor appears in response to transfusion therapy with factor concentrates with no correlation of occurrence and amount of therapy. Factor VIII inhibitors may occur spontaneously in the postpartum patient, with certain malignancies, in association with autoimmune disorders (eg, rheumatoid arthritis, systemic lupus erythematosus), in the elderly, and for no apparent reason.
-Other acquired causes of increased bleeding include paraproteinemia; other factor-specific inhibitors, including those against factor V, factor XI; or virtually any of the coagulation proteins.
-Acute disseminated intravascular coagulation/intravascular coagulation and fibrinolysis (DIC/ICF), which is a fairly common cause of bleeding. Bleeding can also occur in patients with chronic ICF.
An interpretive report will be provided.
An interpretive report will be provided.
This test is not useful for assessing platelet function (eg, congenital or acquired disorders such as Glanzmann thrombasthenia, Bernard-Soulier syndrome, storage pool disease, myeloproliferative disease, associated platelet dysfunction), which requires fresh platelets.
Patient should not be receiving Coumadin or heparin. If the patient is currently on warfarin or heparin, this should be noted, as warfarin or heparin therapy can affect certain coagulation factors or assays, preclude their performance, or cause spurious results. Patient should also not be receiving fibrinolytic agents (streptokinase, urokinase, tissue plasminogen activator [tPA]).
If patient has been recently transfused, this should be noted; it is best to perform this study pretransfusion, if possible.