• Mixing study: useful if f PT or PIT: mix Pt's plasma 1:1 w normal plasma and retest
PT PTT normalizes — factor deficiency: PT Ml I remains elevated — factor inhibitor
• Coagulation factor levels: useful if mixing study suggests factor deficiency
DIC • all factors consumed:.. i factor V and VIII
liver disease 1 all factors except VIII; : factor V, normal factor VIII
vitamin K deficiency i factors II,VII, IX, X (and protein C, S):. normal V and VIII
• DIC screen: fibrinogen (consumed), fibrin degradation products (FDPs, due to intense fibrinolysis). D-dimer (more specific FDP test that detects degradation of X-Iinked fibrin)
Hemophilias (nejm 2001:344:1773) I
• X-linked factor VIII (hemophilia A) or factor IX (hemophilia B) deficiency
• Classification: mild (5-25% normal factor activity), moderate (1-5%). or severe (< 1%)
• Clinical manifestations: hematomas, hemarthroses. bruising, bleeding (mucosal. Gl, GU)
• Diagnosis: ? PTT (normalizes w mixing study), normal PT & vWF. i factor VIII or IX
• Treatment: purified recomb. factor VIII or IX concentrate, desmopressin (mild disease).
aminocaproic acid; recomb. factor Vila if factor inhib.. cryo (only has factor VIII) Coagulation factor inhibitors
• Etiologies: hemophilia (treated with factor replacement); postpartum; fymphoproliferative '
disorders and other malignancies; autoimmune diseases; most commonly anti-factor VIII
• Diagnosis: i PTT (does not normalize w mixing study): Bethesda assay quantitates titer
• Treatment: high titer — recomb. factor Vila, porcine factor concentrates, activated prothrombin complex; others high-purity human factor, plasmapheresis, immune tol.
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