Hemostatic System - general information Normal hemostatic system –vessel wall –circulating blood platelets –blood coagulation and fibrynolysis Platelets.

Presentation on theme: "Hemostatic System - general information Normal hemostatic system –vessel wall –circulating blood platelets –blood coagulation and fibrynolysis Platelets."— Presentation transcript:

1 Hemostatic System - general information Normal hemostatic system –vessel wall –circulating blood platelets –blood coagulation and fibrynolysis Platelets –disc-shape cells –arise from megakariocytes in bone marrow –1/3 of platelets are sequestrated in the spleen –other 2/3 circulate for 7-10 days –are responsible for primary hemostasis –normal platelet count : 150-450 G/l

2 Bleeding Diathesis Is caused by inherited or acquired defects of –vessel wall –platelets number and/or function –coagulation system Is charcterised by –spontaneous bleeding –extensive bleeding after minimal trauma

3 Platelets Disorder Disorder of platelet number –thrombocytopenia –thrombocytosis Disorder of platelet function

4 Disorder of platelets function defects of platelet adhesion –inherited: vonWillebrandt’s disease, Bernard-Soulier syndrome –acquired: uremia defects of platelet aggregation –inherited: Glantzmann’s thrombasthenia –acquired: dysproteinemia, drug ingestion (ticlopidin) defects of platelet release –inherited: grey-platelet, Hermansky-Pudlak,Chediac-Higashi syndr. –acquired: cardiopulmonary bypass, myeloproliferative disorders, drugs

5 Thrombocytosis Thrombocytosis resulting from myeloproliferation –essential thrombocythemia –polycythemia vera –chronic myelogenous leukemia –myeloid metaplasia Secondary (reactive) thrombocytosis –systemic inflammation –malignancy –iron deficiency –hemorrhage –postsplenectomy

6 Thrombocytopenia (1) Decreased marrow production of megakariocytes congenital disorders –thrombocytopenia with absent radii (TAR) –Fanconi’s anemia –May-Hegglin anomaly acquired disorders –marrow infiltration with malignant cells –marrow fibrosis –aplastic and hypoplastic anemias ( idiopathic, drugs, toxins ) –deficiency states ( vitamin B12, folate, iron ) –paroxysmal nocturnal hemoglobinuria

7 Thrombocytopenia (2) Splenic sequestration of circulating platelets splenic enlargement due to tumor infiltration splenic enlargement due to portal hypertension

8 Thrombocytopenia (3) Increased destruction of circulating platelets congenital disorder –Wiscott-Aldrich syndrome, Bernard-Soulier syndrome acquired disorders nonimmune destruction –vascular prostheses, cardiac valves –DIC –hemolytic-uremic syndrome/thrombotic thrombocytopenic purpura –sepsis immune destruction –idiopathic thrombocytopenic purpura ( ITP ) acute and chronic –drug-induced thrombocytopenia –chronic autoimmune disorders –infection (HIV) –malignancies

9 Platelets Disorder - signs and symptoms asymptomatic if platelets count > 50 G/l onset of bleeding after trauma - immediate site of bleeding - superficial: skin, mucous membranes, nose, genitourinary tract physical finding - petechiae, ecchymoses

10 Idiopathic Thrombocytopenic Purpura (1) the most common cause of isolated thrombocytopenia autoimmune disease with antiplatelet antibodies and shortened platelets life span forms of ITP acute ITP –children (90% of pediatric case of immune thrombocytopenia) – preceded by viral infection –spontaneous recovery within 4-6 weeks in 60% of patients chronic ITP –20-40 years –women predominance F:M=3:1

11 Idiopathic Thrombocytopenic Purpura (2) Clinical features –petechiae –ecchymoses –mucose membranes bleeding –menorrhagia –rare internal, intracranial bleeding Diagnosis –platelet count <100G/l –bleeding time - usually normal –peripheral blood smear - large platelets –bone marrow examination - normal or increased number of megakariocytes –antibodies against Gp IIb/IIIa –shortened platelet survival

12 Treatment of ITP not necessary unless platelets count > 20G/l or there is extensive bleeding corticosteroids permanent responses - 30% –prednisone 1mg/kg for 4-6 weeks splenectomypermanent responses - 60% immunosuppresive drugs intravenous immunoglobulins other - danazol, antiRhD