Hemostasis and Coagulation 1

Intended Learning Outcomes (ILOs) Discuss laboratory evaluation of hemostatic function. Design a plan to diagnose a case of thrombocytopenia. Recall causes of prolonged prothrombin time (PT) Recall causes of prolonged activated partial thromboplastin time (APTT) Demonestrate laboratory profile of Von Willebrand Disease. - Interpret various cases characterized by hemostatic function defect.

Components of hemostasis Hemostasis: is the process by which bleeding is arrested after injury to blood vessels Normal hemostasis requires the interaction of platelets and clotting cascade with normal blood vessels

Balance in Hemostasis Haemostasis depends on a delicate balance between procoagulant and anticoagulant mechanisms A disruption of this unique balance may cause bleeding or thrombosis Hemostasis Anticoagulant Procoagulant Thrombosis Anticoagulant Procoagulant Bleeding Anticoagulant Procoagulant

Mechanism of coagulation Intrinsic pathway Extrinsic pathway XIIa contact factors TF XIa VIIa lXa Xa VIIIa Test: PTT Test: PT Va Ca++ finronolysis II IIa Fibrinogen Fibrin

Presentation Bleeding Tendency: Excessive bleeding (spontaneous/ after injury) Easy hematoma formation after minor trauma Recurrent epistaxis Menorrhagia Abnormal bleeding during operation , or post operative Petichae, purpuric eruption, ecchymosis Thrombosis: Deep venous thrombosis (DVT)

LABORATORY EVALUATION OF HEMOSTATIC FUNCTION Screening tests: done for all suspected patients Bleeding time Platelet count Prothombin time (PT) Partial thromboplastin time (PTT) Thrombin time (TT) Specific tests : done according to results of screening tests 7

BLEEDING TIME Time needed to stop bleeding after induced needle prick Affected by Platelet count Platelet function Vessel wall Normal range: Ivy’s method: up to 7 min Note: it is not a sensitive test for minor or even moderate abnormality. 8

Bleeding time: BT Causes of prolonged bleeding time: 1-Thrombocytopenia (moderate or severe). 2-Disorders of platelet function. *VWD *Glanzmann’s disease *Bernard Soulier syndrome 3-Vascular abnormalities

PLATELET COUNT Normal platelet count = 150-400 x109/L A part of complete blood picture (CBC) Performed by electronic counters or manually Note: Any case of unexpected very low platelet count should be rechecked particularly in infants and young children when sampling is difficult. 10

Investigation of a case of thrombocytopenia History CBC Bone Marrow ANA

QUALITATIVE PLATELET DEFECT In a case presenting with purpura and normal platelet count and other coagulation tests you have to suspect defective platelet functions. 12

Tests Morphology of platelet in smear Platelet aggregation

PROTHROMBIN TIME (PT) Test for extrinsic pathway (FVII, FII, FV, X) [majority are vitamin K dependent factor]. Used for monitoring oral anticoagulant therapy and used as a liver function test Normal range: 10-14 sec 14

Prothrombin Time PT Tissue extract ca Fibrin clot Plasma

Causes of prolonged PT Oral anticoagulants Liver disease Vit K deficiency (FII, VII , IX and X ) Congenital deficiency of factors involved in extrinsic pathway. DIC inhibitors 16

Reporting Of PT Test Example Patient : 12 sec Control : 11 sec INR : 1.1

PARTIAL THROMBOPLASTIN (PTT) It is a test for intrinsic pathway of blood coagulation (FVIII, FIX, FXI, FXII, FII, FV, X). It is the test Used for patients receiving heparin therapy Normal range: 30-40 sec 18

Causes of prolonged PTT 19

Causes of prolonged PTT Heparin Deficiency of factors involved in intrinsic pathway, usually congenital: Hemophilia A Hemophilia B and von Willebrand disease) DIC Massive transfusion (labile FV, FVIII) Inhibitors 20

BT PT PTT Platelet count Platelet function Other tests ITP Glanzman disease Bernard Soulier S Hemoph A Hemoph B vWD DIC 21

To summarize

Investigation Of Bleeding Disorder

APTT Bleeding Time (BT) Prolonged Normal Platelets Count Platelets Function Blood vessels Check PT APTT APTT Hemophilia Heparin PT Oral AC

Prothrombin Time (PT) Prolonged Oral anticoagulant Vitamin K deficiency Liver Disease DIC inhibitors

Activated Partial Thromboplastin Time (aPTT) Heparin anticoagulant Prolonged Heparin anticoagulant Hemophilia Massive Liver Disease DIC inhibitors Von Willebrand Disease

Prolonged (BT) + Prolonged APTT+ Normal PT Von Willebrand Disease Prolonged (BT) + Prolonged APTT+ Prolonged PT Massive Liver Disease DIC

Case study

bleeding time 10 min (normal, 2-7 min) Case 1 A 32-years old woman observes the presence of multiple petechiae, purpura and ecchymosis rashes when she wakes up in the morning . She had a history of epistaxis requiring cauterization. platelet count 50 x 109/L bleeding time 10 min (normal, 2-7 min) This woman might be suffering from: a-Immune thrombocytopenic purpura b-Von Willebrand disease c-Glanzmann’s disease d-a, b & c e-b & c 29

bleeding time 10 min (normal, 2-7 min) Case 2 A 19-years old woman complained of prolonged menstrual bleeding. She had a history of epistaxis requiring cauterization. platelet count 180 x 109/L bleeding time 10 min (normal, 2-7 min) This woman might be suffering from: a-immune thrombocytopenic purpura b-von Willebrand disease c-Glanzmann’s disease d- a, b & c e-b & c 30

Case 3 A 3 year old boy presents with a painful left elbow after mild trauma. Evaluation reveals a hemarthrosis. Platelets count is 190X109/L BT & PT are normal PTT is prolonged Which of the following is the most likely diagnosis? hemophilia A Von Willebrand Disease Bernard Soulier syndrome immune thrombocytopenic purpura aspirin intake

Case 4 A 30 year old man presents with easy bruising PT 13 seconds (normal, 10-14 seconds) PTT 60 seconds (normal, 30-40 seconds) BT 11 minutes (normal 2-7 minutes) Which of the following is the most likely diagnosis? hemophilia A hemophilia B von Willebrand disease immune thrombocytopenic purpura aspirin intake 32

CASE 5 A 42 year-old man brought to the emergency room with severe second- and third-degree burns. SCREENING COAGULATION LABORATORY RESULTS PT= 17 sec (Normal 8-11.5) aPTT= 49 sec (Normal 24-37.5) Platelet count= 20,000 /μL hemophilia A hemophilia B von Willebrand disease DIC Glanzmann’s disease

BT PT PTT Platelet count Platelet function Other tests ITP P N Bone marrow Glanzman disease Defect aggreg Hemoph A FVIII assay Hemoph B FIX assay vWD FVIII, vWF DIC Fibrinogen FDPs 34

THROMBOPHILIA

Group of disorders that predispose to venous thrombosis THROMBOPHILIA Heritable thrombophilia Acquired thrombophilia Group of disorders that predispose to venous thrombosis

INHERETED THROMBOPHILIA ACQUIRED THROMBOPHILIA Anti-thrombin deficiency Iatrogenic: surgery -hormonal therapy – chemo/radiotherapy – drugs Protein C deficiency Environmental: Age - obesity -pregnancy – trauma – Immobility Protein S deficiency Disease related: APS – Neoplasia – MPN – PNH – TTP – Inflammation – stroke -SCD Factor V leiden (FV R 506 Q) Prothrombin G20210A mutation MTHFR

DIAGNOSIS HEREDITARY THROMBOPHILIA Assays for: AT-III, Protein C Protein S Molecular studies for: FV leiden Prothrombin G20210A Homocysteinaemia ACQUIRED THROMBOPHILIA: Tests for APS, Lupus Anti-coagulant

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