1. PT & aPTT Manish Pandey

2. Hemostasis Is a Balance Between Clot Formation & Clot Dissolution.

3. Normal Hemostasis Clot formation (Coagulation) Clot dissolution (Fibrinolysis) PT aPTT Thrombin Time Fibrinogen Individual factor tests FDP D-Dimer vWF HMWK Prekallikrein

11. Coagulation Factors Both Calcium IV Pathway Trivial Name Factor Extrinsic Tissue Factor III Both Prothrombin II Both Fibrinogen I Intrinsic Contact activation cofactor HMWK Intrinsic Fletcher factor Prekallikrein

12. Intrinsic Antihemophilic factor B XI Intrinsic Antihemophilic factor A VIII Extrinsic Proconvertin VII Both Accelerin VI (Va) Both Proaccelerin, Labile factor V

13. Both Fibrin Stabilizing factor XIII Intrinsic Hageman Factor XII

20. Mixing studies in PT PT mixing study (1:1 mix of patient and normal plasma PT normalizes Factor Deficiency; Measure factors I, II, V, VII, X PT initially shortens and then prolongs Factor V inhibitor (rare) aPTT remains prolonged Inhibitor (specific factor inhibitor, rare) Treat specimen with heparinase (degrades heparin) PT normal, prolongation due to heparin PT prolonged

21. Mixing studies in aPTT aPTT mixing study (1:1 mix of patient and normal plasma aPTT normalizes Factor Deficiency; Measure factors VIII, IX, XI, XII aPTT initially shortens and then prolongs Factor VIII inhibitor aPTT remains prolonged Inhibitor, most commonly Lupus Anticoagulant Treat specimen with heparinase (degrades heparin) aPTT normal, prolongation due to heparin aPTT prolonged