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56 Cards in this Set

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  • Back
What are disorders of primary hemostasis?
1) Defects of initial platelet plug formation
2) Characterized by bleeding from small vessels and capillaries, resulting in mucocutaneous bleeding. Petechial (pinpoint or punctate) hemorrhages occur in the skin and mucous membranes, with bleeding and oozing form the nose (epistaxis), gums, and gastrointestinal tract.
3) Often marked by prolonged bleeding time. Other tests, such as the prothrombin time, activated partial thromboplastin time (APTT or PTT), etc., are characteristically normal.
4) Can be caused by lesions of the vasculature, by thrombocytopenia or platelet dysfunction such as Glanzman thrombosthenia, or by alterations in the plasma proteins required for adhesion of platelets to vascular subendothelium.
What are lesions of the vasculature?
Usually no laboratory abnormalities are associated wiht bleeding due to small blood vessel dysfunction, but a prolonged bleeding time is sometimes noted.
2) Simple purpura
3) Senile purpura
4) Scurvy
5) Henoch-Schonlein purpura
6) Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome)
7) Connective tissue disorders
8) Waldenstrom macroglobulinemia
9) Amyooidosis
10 Rickettsial and meningococcal diseases.
What is simple purpura?
Easy bruising, especially of hte upper thighs, in otherwise healthy persons
What is senile purpura?
1) marked by hemorrhagic areas on the back of the hands and forearms of older persons
2) Presumed to arise from age-dependent atrophy of vascular supportive tissue
What is scurvy?
1) Vitamin C deficiency
2) Characterized clinically by extensive primary hemostatic bleeding with gingival hemorrhages, bleeding into muscles and subcutaneous tissue, and cutaneous petechiae characteristicaly occurring about hair follicles.
What is Henoch-Schonlein purpura (allergic purpura)?
1) Form of leukocytoclastic angiitis, hypersensitivity vasculitis resulting from an inmmune reaction that damages the vascular endothelium.
2) marked by hemorrhagic urticaria (palpable purpura) accompanied by fever, arthralgias, and GI and renal involvement.
What is hereditary hemorrhagic telangiectasia (Osler-Webber-Rendu syndrome)?
An autosomal dominant disorder marked by localized malformations of venules and capillaries of the skin and mucous membranes, often complicated by hemorrhage.
What are CT disorders?
Include Ehlers-Danlos syndrome, an inherited disorder caused by abnormalities of collagen or elastin and manifested by vascular bleeding, articular hypermobility, dermal hyperelasticity, and tissue fragility.
What is Waldenstrom macroglobulinemia?
1) Produces vascular damage from sludging of hyperviscous blood.
2) Can also cause platelet functional abnormalities.
What can Amyloidosis do to the body in regards to lesions of vasculature?
Cause vessel damage
What do Rickettsial and meningococcal diseases have to do with lesions of vasculature?
1) Include Rocky Mountain spotted fever and meningococcemia
2) Involve the vascular endothelium, leading to necrosis and rupture of small blood vessels.
What is Thrombocytopenia?
1) Dominated clinically be petechial cutaneous bleeding, intracranial bleeding, and oozing from mucosal surfaces.
2) Charracterized by decreased platelet count and prolonged bleeding time; bone marrow aspiration reveals decreased megakaryocytes when caused by decreased platelet production and increased megakaryocytes when caused by increased platelet destruction.
3) Result of decreased production, increased destruction, unreplaced loss, or dilution of platelets, brought about by a wide variety of etiologic factors.
How does irradiation, exposure to drugs or chemical cause thrombocytopenia?
Causes decreased production
How does acute leukemia cause thrombocytopenia?
Caused decreased production because of replacement of bone marrow by blast cells.
How does myelophthisis cause thrombocytopenia?
Causes decreased production because of bone marrow replacemt, usually by tumor cells.
How dies aplastic anemia cause thrombocytopenia?
1) Often caused by exposure to toxic agents such as benzene
2) Can also be due to autoimmune destruction by cytotoxic T cells.
How does splenic sequestration lead to thrombocytopenia?
Results in loss of circulating platelets
How do multiple transfusions lead to thrombocytopenia?
Results in dilution
How does disseminated intravascular coagulation (DIC) lead to thrombocytopenia?
Results in depletion of platelets.
To what other diseases is thrombocytopenia secondary?
AIDS & SLE
What is idiopathic thrombocytopenic purpura (ITP)?
1) Also known as immune (or autoimmune) thrombocytopenic purpura.
2) In children, is usually an acute, self-limiting reaction to viral infection or immunization; in adults, is a chronic disorder.
3) Characterized by antiplatelet antibodies that coat and damage platelets, which are then selectively removed by splenic macrophages. Maternal IgG antibodies in affected mothers can cause fetal thrombocytopenia
4) Diagnosed based on thrombocytopenia wiht normal or increased megakaryocytes, no known exposure to thrombocytopenic agents, and lack of palpable splenomegaly.
What is Thrombotic thrombocytopenic purpura (TTP)?
1) Characterized by hyaline microthrombi in small vessels, thrombocytopenia, and microangiopathic hemolytic anemia. The microcirculatory lesions produce mechanical damage to red blood cells as they squeeze through the narrowed vessels, resulting in helmet cells and schistocytes.
2) Also marked by transient neurologic abnormalities, renal insufficiency, and fever.
What are platelet functional abnormalities?
1) Platelet-mediated bleeding disorders that occur in spite of normal platelet count
2) Results in mucocutaneous bleeding and are often associated wiht a prolonged bleeding time.
What causes platelet functional abnormalities?
1) Defects of platelet adhesion; von Willebrand disease; Bernard-Soulier disease
2) Defects of platelet aggregation
What are defects of platelet adhesion.
Von Willebrand disease and Bernard-Soulier disease, an autosomal recessive disorder characterized by unusually large platelets and by lack of platelet-surface glycoprotein (GPIb-IX) needed for platelet adhesion
What are defects of platelet aggregation?
1) Can be either acquired or inherited
2) Aspirin-induced acetylation and inactivation of cyclooxygenase, which caused failure of synthesis of the platelet aggregant thromboxane A2
3) Glanzmann thrombasthenia, inaggregability of platelets due to hereditary deficiency of platelet-surface GPIIb-IIIa, required for formation of fibrinogen bridges between adjacent platelets.
What are disorders of secondary hemostasis?
1) Caused by deficiencies of plasma clotting factors of the coagulation cascade
2) Manifest by bleeding from larger vessels, resulting in hemarthroses large hematomas, large echymoses, and extensive bleeding with trauma.
3) Do not affect the bleeding time or platelet count (thus distinguishing secondary hemostatic disorders form primary hemostatic disorders).
4) May result in abnormalities in the PT, reflecting deficiencies of fibrinogen or factors II, V, VII, and X; APTT (or PTT), reflecting deficiencies of all of the coagulation factors with the exception of factors VII and XIII; and thrombin time, reflecting deficiency of fibrinogen. (The whole blood clotting time is an older test that detects the same abnormalities as the APTT)
What is classic hemophelia?
1) Hemophilia A, factor VIII deficiency
2) Common X-linked disorder with worldwide distribution that varies in severity, depending on factor VIII actiity. Severe cases have less than 1% residual factor VIII activity.
3) Characterized by bleeding into muscles, subcutaneous tissues, and joints.
4) Associated wiht prolongation of hte APTT (or PTT) and a normal bleeding time, platelet count, PT, and thrombin time. The prolonged APTT can be corrected in vitro by the addition of normal plasma.
What is Christmas disease?
1) Hemophilia B, factor IX deficiency
2) Occurs in approximately one fifthe to one thenth the incidence of classic hemophilia
3) Indistinguishable from classic hemophilia in mode of inheritance and clinical features
What is vitamin K deficiency?
1) In adults, is most often caused by fat malabsorption from pancreatic or small-bowel disease
2) In neonates, causes hemorrhagic disease of hte newborn, which is due to deficient exogenous vitamin K in breast milk in association with incomplete intestinal colonization by vitamin K-synthesizing bacteria.
3) Results in decreased activity of clotting factors II, Vii, IX, and X and is reflected by prolongation of the PT and APTT
What is von Willebrand disease?
1) Most common hereditary bleeding disorder
2) Autosomal disorder marked by deficiency of von Willebrand factor, a large multimeric protein synthesized by endothelial cells and megakaryocytes.
3) Characterized by impaired platelet adhesion, prolonged bleeding tiime adn functional deficiency of factor VIII.
What is the function of vWF?
1) Carrier protein for factor VIII (antihemophilic factor),and the two proteins circulate together as a complex.
2) Also mediates adhesion of platelets to subendothelium at sites of vascular injury, reacting with the subendothelium and hte platelet-surface glycoprotein complex GPI-IX-V
What are dual hemostati defects?
1) Deficiency of vWF leads to a failure of platelet adhesion, resulting in deficient platelet plug formation manifest clinically by primary hemostatic bleeding and prolonged bleeding time.
2) A functional deficiency of factor VIII occurs as a consequence of the deficit of vWF, its carrier protein. Deficiency is manifest by secondary hemostatic bleeding and prolonged APTT
What is DIC characterized by?
Widespread clotting wiht resultant consumption of platelets and coagulation factors, especially factors II, V, and VIII and fibrinogen.
How is DIC clinically manifest?
By thrombotic phenomena and hemorrhage.
By what is DIC marked?
1) Microangiopathic hemolytic anemia wiht fragmented red cells (schistocytes), increased fibrin and fibrinogen degradation (split) products, thrombocytopenia, and prolonged bleeding time, PT, APTT, and thrombin time
2) Microthrombi in the small vessels of many organs.
How is DIC caused?
By release of tissue thromboplastin (tissue factor) or activation of the intrinsic pathway of coagulation, as well as by secondary activation of the fibrinolytic system.
Where is DIC most commonly seen?
1) Obstetric Complications, such as toxemia, amniotic fluid emboli, retained dead fetus, or abruptio placentae
2) Can also result form cancer, notably of the lung, pancreas, prostate, or stomach
3) From tissue damage caused by infection, especially G- sepsis; trauma, as in chest surgery, or immunologic mechanisms, especially immune complex disease or hemolytic transfusion reactions.
What is coagulopathy of liver disease?
1) Arises because all coagulation factors except vWF are produced in teh liver; therefore, as hepatocellular damage progresses, the PT, APTT, adn thrombin time are prolonged. In addition, prolonged bleeding time due to platelet functional defects or overt thrombocytopenia may occur.
2) May be alleviated in some cases by administration of vitamin K derivatives, which promote carboxylation of glutamyl residues of precursors of factors II, VII, IX, and X
What is dilutional coagulopathy?
1) May result form multiple transfusions of stored blood deficient in platelets and factors II, V, and VIII.
2) Often manifest by persistent bleeding from surgical wounds.
3) May result in thrombocytopenia or prolonged PT or APTT.
What hemorrhagic disorders lead to prolonged bleeding time?
Thrombocytopenia
Qualitative platelet defects
von Willebrand disease
DIC
What hemorrhagic disorders have an unusually prolonged bleeding time?
Vascular bleeding defects
What hemorrhagic disorders have normal bleeding time?
Classic hemophilia
Christmas disease
What Hemorrhagic disorders have a normal platelet count?
Vascular bleeding defects
Qualitative platelet defects
Classic hemophilia
Christmas disease
von Willebrand disease
What hemorrhagic disorders have decreased platelet count?
Thrombocytopenia
DIC
What hemorrhagic disorders have prolonged PT?
DIC
What hemorrhagic disorders have normal PT?
Vascular bleeding defects
Thrombocytopenia
Qualitative platelet defects
Classic hemophilia
Christmas disease
von Willebrand disease
What hemorrhagic disorders have normal APTT?
Vascular bleeding defects
Thrombocytopenia
Qualitative platelet defects
What hemorrhagic disorders have prolonged APTT?
Classic hemophilia
Christmas disease
von Willebrand disease
DIC
What hemorrhagic disorders have normal Thrombin Time/Fibrinogen Assay?
Vasculaar bleeding defects
Thrombocytopenia
Qualitative platelet defects
Classic Hemophilia
Christmas disease
von Willebrand disease
What are the confirmatory tests for thrombocytopenia?
Megakaryocytes normal or increased when thrombocytopenia is caused by increased platelet destruction, decreased when due to decreased production
What are the confirmatory tests for qualitative platelet defects?
Platelet aggregation and other specialized studies.
What are teh confirmatory tests for classic hemophilia?
Factor VIII assay
What are the confirmatory tests for Christmas disease?
Factor IX assay
What are the confirmatory tests for von Willebrand disease?
vWF assay
What are the confirmatory tests for DIC?
Fibrin and fibrinogen degradation products.