Platelets, coagulation system

overview of platelets and the coagulation system

1. Platelets, and Coagulation System Fadel Muhammad Garishah, BSc

2. Thrombosis and Virchow’s Triad

3. Platelets Megakaryocytes’ daughters Actors of primary thrombosis Activated and inhibited by various stimuli Also involved in both hemostatic and immunity-inflammation processes

4. Endothelial cells Lining of the vascular system Possessed various adhesion molecules for the adhesion of platelets, WBCs during thrombosis and inflammation processes

5. Hemostasis – Thrombosis - Fibrinolysis http:// www.hopkinsmedicine.org /hematology/ coagulation.swf

6. Platelet Activation

7. Coagulation Cascade and Fibrin Polymerization

8. Fibrinolysis

9. Clinical Evaluation of Thrombosis Clotting Time Bleeding Time Prothrombin Time Activated Partial Thromboplastin Time

10. Bleeding time Platelet functions to form clot Wound in superficial area -> normally 1-9 min stops Prolonged: platelet dysfunction, vWD , anticoagulant use, uremia, liver failure, leukemias , MDS

11. Thrombin time Assess fibrin formation in plasma TT time < 20 seconds Shortened: hereditary, DIC, multple myeloma

12. Prothrombin Time Extrinsic factors and final common pathway Factor II, V, VII, X Adding Ca2+ and thromboplastin (activator) to blood sample, and then measure the time PT 9,5 – 13,5 seconds INR < 1. Prolonged PT: warfarin use, def vit K, liver disease, deficiency of F II, VIII, V, X, DIC, fibrinogen abnormalities, heparinization

13. Partial Thromboplastin Time or Activated Partial Thromboplastin Time Intrinsic coltting factors etc aPTT additional activator that speeds up PTT aPTT 30-40 seconds PTT 60 – 70 seconds Prolonged causes: Def F VIII, IX, XI, XII, Fitzgeralnd / prekalikrein , vWD , hypofibrinogenemia , liver cirrhosis, def vit K, , DIC, heparinization , coumarin inhibition FI, IX and X Shortened: early DIC, cancers, hemorrhage,