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80 Cards in this Set
- Front
- Back
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What are the lab findings for vascular and extravascular disorders? |
Bleeding time: Prolonged Closure time: Prolonged Capillary fragility tests: Positive PLT count: Normal PT: Normal APTT: Normal |
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describe senile purpura |
bruising in the aged due to atrophy and degeneration of subendothelial connective tissues |
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describe simple easy bruising |
occurs in many women of reproductive age and is often accompanied by thrombocytopenia. Possible caused by estrogens |
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Describe secondary vascular purpuras |
endothelial damage from a variety of causes. (immune damage, uremia, hypertension, vitamin c deficiency, infective organisms, endotoxins, mechanically induced hypoxia, increased body pressure, steroid drug administration, cushing disease, chronic liver infections, liver disease, henoch-schoenlein syndrome, etc) |
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Name the acquired vascular disorders |
Senile purpura simple easy bruising secondary vascular purpuras |
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Name the inhereited vascular and extravascular disorders |
Hereditary Hemorrhagic Telangiectasia (HHT or Osler-Weber-Rendu Disease) Other inborn errors of collagen biosynthesis: -Ehlers-Danlos Syndromes -Marfan Syndrome -Osteogenesis Imperfecta -Homocystinuria -Pseudo Xamthoma elasticum |
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Describe Hereditary Hemorrhagic Telangiectasia (HHT or Osler-Weber-Rendu Disease |
Autosomal dominant defect in subendothelial collagen Results in -dilations of capillaries (telangiectasia) -Loss of vascular patency producing petechiae -spontaneous bleeds from mucous membranes --nosebleeds in children, GI bleeding with aging |
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Describe Ehlers Danlos Syndromes |
loss of elasticity in the epidermis and sub epidermal tissues -very deformable skin |
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describe marfan syndrome |
defect in chromosome 15 resulting in abnormal fibrillan in connective tissue and weakness. Aortic prolapse is one serious consequence |
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describe osteogenesis Imperfecta |
a genetic disorder of defective collagen formation characterized by bones that break easily. |
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describe homocystinuria |
an inherited disorder of the metabolism of the amino acid methionine |
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describe pseudo xanthoma elasticum |
an inherited disorder of elastin in which elastic tissues in the body (skin, vessels, retina) become mineralized, especially with calcium |
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Disorders of the platelets are either: |
Quantitative due to abnormal numbers of platelets in circulation Qualitative functional defects |
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what is the most common cause of abnormal bleeding? |
thrombocytopenia |
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define thrombocytopenia |
decrease in the number of platelets in the blood below normal values (<150 x 10^9/L) Usually count drops below 120 before there is any noticeable bruising and below 20 before there is severe or spontaneous bleeding |
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what are the clinical findings in thrombocytopenia? |
skin purpura, bruising and petechiae mucosal hemorrhages increased bleeding after trauma nosebleeds (epistaxis) |
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what are the laboratory findings in thrombocytopenia? |
Platelet cound below 150x10^9/L bleeding time prolonged closure time prolonged clot retraction poor (<50%) |
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What causes thrombocytopenias? |
Decreased of ineffective production of platelets Increased destruction or utilization of platelets Abnormal distribution of platelets |
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what is the most common cause of low platelet counts? |
decreased production of platelets |
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define marrow hypoplasia |
decreased production of platelets in bone marrow due to: -inherited causes (such as wiscott-aldrich syndrome) -acquired causes (drugs, chemicals, radiation) -overcrowding or replacement of normal hematopeoitic cells in the marrow, as in acute leukemia, myelofibrosis |
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what are the specific lab findings in thrombocytopenia due to hypoplasia? |
low platelet count decreased megakaryocytes in the bone marrow very few megathrombocytes in the blood smear |
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what are the specific lab findings in ineffective thrombopoiesis? |
low platelet count, normal looking marrow |
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What can explain increased destruction or utilization of platelets? |
excessive consumption of platelets platelet antibodies transfusions
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what conditions consume excessive platelets? |
thrombotic thrombocytopenic purpura (TTP disseminated intravascular coagulation (DIC) hemolytic uremic syndrome (HUS) |
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Describe TTP |
Rare, often fatal disorder caused by a deficiency of the metalloprotease enzyme ADAMTS-13 The enzyme is required to break up Ultra Large von Willebrand' factor adhesive multimers. deficiency is either congenital or due to ADAMTS-13 autoantibodies TTP results in the presence of ULVWF multimers in the plasma and inappropriate and widespread platelet aggregation and thrombi. |
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what are the specific lab findings in TTP? |
increased megakaryocytes in the bone marrow, increased megathrombocytes in the blood smear, increased platelet aggregation seen in the blood film and decreased platelet survival (radioisotope method) |
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Describe ITP |
immune thrombocytopenic purpura (ITP) platelet antibody (usually GPIIb/IIIa) sensitizes the platelets and causes their premature removal by macrophages in the spleen usually secondary to viral infections or drugs, can be for no apparent reason |
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what are the specific laboratory findings in ITP? |
increased megakaryocytes in bone marrow platelet antibody in the patients serum PLT count 10-50x10^9/L decreased platelet survival |
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In what way can transfusions cause thrombocytopenia? |
dilution with platelet poor donor blood donor platelets may be sensitized by platelet antibody formed in the patient after a prior transfusion platelets may be lost in extravascular circulation (e.g. heart pump or renal dialyser) |
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define thrombocytosis |
platelet count is over 400x10^9/L |
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define thrombocythemia |
platelet count is over 1000x10^9/L |
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what are the lab findings in thrombocytosis? |
increased platelet count abnormal platelet morphology increased megathrombocytes increased red cell fallout in the clot retraction test normal or prolonged bleeding time |
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What indicates abnormal platelet function? |
skin and mucosal hemorrhage prolonged bleeding time normal platelet count |
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Define thrombopathies |
inherited defects of the platelet release reaction
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what are the two types of thrombopathies? |
Storage pool disease Defective release of ADP during aggregation |
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Describe storage pool disease |
most cases involve decreased release of ADP from aggregating platelets due to a deficiency of ADP in the dense granules of the platelets. occures in albinos and in association with Wiscott-Aldrich Syndrome and Chediak-Higashi Syndrome. Few cases involve a deficiency of alpha granules |
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what are the laboratory findings of thrombopathies? |
bleeding time is moderately prolonged platelet aggregation is decreased (improved with the addition of ADP) PF3 availability is decreased |
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describe thromboasthenia (glanzmann disease) |
an inherited failure of primary aggregation caused by reduced amounts of the membrane glycoprotein complex GPIIB/IIIa. Aggregation fails because fibrinogen cannot be bound to the platelet membrane |
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what are the laboratory findings in thrombasthenia (glanzmann disease) |
bleeding time is greatly prolonged clot retraction is defective platelet adhesion to collagen is normal platelet aggregation is abnormal with ADP, epinephrine, thrombin and serotonin, but normal with ristocetin Platelet count is normal |
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describe Bernard-Soulier Syndrome (BSS) |
also known as Giant platelet syndrome a sever inherited failure of platelet adhesion caused by reduced amounts of membrane glycoprotein IN/IX. adhesion fails because vWF cannot be bound to the platelet membrane. The disorder shows sever subcutaneous, mucosal, and visceral bleeding, which is ofen fatal |
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what are the laboratory findings in Bernard-Soulier Syndrome? |
many very large megathrombocytes (up to 20 micrometers in diameter) with increased numbers of dense granules more than 80% of the platelets are increased in size bleeding time is greatly prolonged platelet count is normal or decreased platelet adhesion is normal in vitro |
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what is the major cause of acquired platelet defects? |
drugs |
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what is the most common implicated drug in aquired platelet defects? |
Aspirin |
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what can cause the failure of clotting factors? |
failure of synthesis (inherited or acquired) production of abnormal molecules (inherited or acquired) excessive destruction or cunsumption of coagulation factors inactivation of coagulation factors by circulating anticoagulants |
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what does laboratory screening for clotting factor defects begin with? |
PT & APTT |
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In which factors does a deficiency produce bleeding proportional to the deficiency? |
IX, VIII, X, V, II, I |
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Which factors does a deficiency give a marked lab defect but no clinical bleeding? What is the marked lab defect? |
XII, HMWK, PK. prolonged APTT |
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What does a deficiency in Factor XIII produce? |
disproportionately severe but delayed bleeding |
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Describe Hemophilia A |
most common hemophilia deficiency in factor VIII: C bleeding is proportional to the deficiency of the factor most abnormal bleeding is internal, in joints, in muscles very painful hematuria is common, GI bleeds uncommon nosebleeds are common and frequently severe operative and post-operative bleeds are life thretening |
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what is the therapy in hemophilia A? |
raise the levels of factor VIII: C Factor VIII available in lyophilized form desmopressin induces VIII release |
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what are the complications in hemophilia A? |
development of immune VIII antibodies in 10-15% of patients development of liver disease due to many infusions of blood products and exposure to hepatitis virus |
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Describe hemophilia B |
inherited deficiency of coagulation factor IX with clinical features similar to classic hemophilia but less severe |
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describe von Willebrand Disease |
not a coagulation disorder disorder of platelet function (adhesion) defect of chromosome 12 results in reduced synthesis of normal von willebrand factor moderate trauma may produce subcatneous bleeding excessive blood loss from cuts, abrasion, and during surgury muscle and joint bleeding rare |
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how is von Willebrand Disease treated? |
infusions of VIII concentrate. much more effective than patients suffering from hemophilia A |
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what are the tests for VWD? |
platelet agglutination test with ristocetin platelet aggregation test with ristocetin
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what should a screening test for a bleeding disorder include? |
platelet count bleeding time PT APTT |
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what are the lab findings for hemophilia A? |
normal platelet count normal bleeding time normal PT prolonged APTT reduced VIIIC |
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what are the lab findings for hemophilia B? |
normal platelet count normal bleeding time normal PT prolonged APTT reduced IX |
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what are the lab findings for VWD? |
platelet count normal bleeding time prolonged (usually) PT normal APTT usually normal vWF reduced platelet agglutination with ristocetin reduced platelet aggregation with ristocetin reduced |
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describe specific coagulation factor antibodies |
acquired pathological coagulation inhibitors (antibodies against coagulation factors) Factor VIII antibodies are most common |
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describe non-specific inhibitors of hemostasis |
antiphospholipid antibodies, including lupus anticoagulant and anticardiolipin antibody |
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what test should be done to indicate appropriate next steps in finding the cause of an abnormal APTT? |
APTT mixing studies |
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describe APTT mixing studies |
normal plasma and patients plasma is mixed and clotting is reassessed. if the clotting is abnormal, a inhibitor/antibody is present if clotting is corrected, a factor deficiency is to blame |
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which factors depend on Vitamin K? |
II, VII, IX, X (and protein C and S) |
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what will a deficiency of vitamin k look like in the lab? |
prolonged PT prolonged APTT decreased assays for II, VII, IX, X and protein C and S |
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what are inactive, abnormal prothrombin group factors called? |
PIVKA proteins induced by vitamin K absence |
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what does liver disease result in? |
a reduction in factors II, VII, IX, X, V, and I |
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describe DIC |
disseminated intravascular coagulation widespread intravascular coagulation results in widespread consumption and destruction of coagulation factors, thrombocytopenia, and abnormal bleeding. |
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what causes DIC? |
anything that causes exposure of a lot of foreign surfaces to the blood (releases lots of FIII or activators of fibrinolysis) |
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what are the laboratory findings for DIC? |
factore deficiencies I, II, V, VIII, XIII prolonged PT, APTT thrombocytopenia increased soluble fibrin monomer complexes increased FDP/fdp increased D dimers decreased antithrombin III increased PF4 schistocytes in microangiopathic hemolytic anemia |
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what are the disorders of fibrinolysis? |
primary fibrinolysis (activation of fibrinolysis in the absence of coagulation) Secondary fibrinolysis (DIC) |
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describe thrombosis |
abnormal formation in circulation of solid, localized masses of fibrin and/or platelets that cause partial or complete occlusion of vessels
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describe a thromboembolism |
a piece of thrombus breaks away and blocks smaller vessels downstream, producing and embolism |
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describe a pulmonary embolism |
and obstruction of the pulmonary artery or one of it's branches by and embolus, usually derive from deep vein thrombosis |
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what is virchow's triad |
three factors important to forming a thrombus -slowing down the flow of blood (stasis) -hypercoagulabilty of the blood -vessel wall damage |
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what are some inherited disorders that promot thrombosis? |
factor V leiden gene mutation antithrombin III deficiency protein C deficiency homocysteinuria dysfibrinogenemia abnormal plasminogen prothrombin G20210A variant |
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describe Factor V Leiden gene mutation |
also known as Protein C resistance produce an abnormal factor V that resists the action of APC, continues to promote coagulation and produces thrombosis |
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describe antithrombin III deficiency |
inadequate inhibition of thrombin, Xa, and IXa |
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describe Homocysteinuria |
damage to the endothelium by deposited homocysteine causes atherosclerosis, adherence of platelets, coagulation and thrombosis |
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what are some acquired conditions and disorders that promote thrombosis? |
surgery and trauma cancer chronic myeloproliferative disorders acute promyelocytic leukemia Lupus anticoagulant kidney nephrosis oral contraceptives |
