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75 Cards in this Set

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how would you describe disorders of primary hemostasis?
- defects of initial platelet plug formation
- you'll get bleeding from small vessels -> mucocutaneous bleeding
- petechial hemorrhages in skin and mucous membranes, with bleeding and oozing from nose, gums, GI
what types of tests are normal and abnormal in disorders of primary hemostasis?
- prolonged bleeding time
- PT, APTT, or PTT are normal
what is APTT?
- activated partial thromboplastin time
what causes disorders of primary hemostasis?
- lesions of the vasculature
- thrombocytopenia
- platelet dysfunction (e.g. Glanzmann thrombasthenia)
- alterations in plasma proteins needed for platelet adhesion to subendothelium
how is the prolonged bleeding time manifested in disorders of primary hemostasis?
1. simple purpura; senile purpura
3. scurvy
4. Henoch-Schonlein purpura
5. Hereditary hemorrhagic telangiectasia
6. Connective tissue disorders
7. Waldenstrom macroglobulinemia
8. Amyloidosis
9. Rickettsial and meningococacal disease
what is simple purpura?
- easy bruising
- usually of upper thighs
what is senile purpura?
- hemorrhagic areas on the back of the hands and forearms of elderly people
- thought to be caused by age-dependent atrophy of vascular supportive tissues
what are the clinical characteristics of scurvy?
- primary hemostatic bleeding with gingival hemorrhages
- bleeding into muscles and subcutaneous tissue
- hemorrhagic perifollicular hyperkeratotic papules
what do hemorrhagic perifollicular hyperkeratotic papules surround? where do you see them?
- surrounds a twisted, corkscrew-like hair
- seen in scurvy
what is Henoch-Schonlein purpura? what subclass does it belong to?
- aka allergic purpura
- a form leukocytoclastic angiitis
- hypersensitivity vasculitis -> damages vascular endothelium
what are characteristic features of henoch schonlein purpura?
- hemorrhagic urticaria (palpable purpura)
- fever
- arthralgias
- GI and renal involvement
what is another name for hereditary hemorrhagic telangiectasia? what is it characterized by? what is it complicated by?
- osler-weber-rendu syndrome
- autosomal dom disorder
- localized malforamtions of venules and capillaries of skin and mucous membranes
- complicated by hemorrhage
what sort of connective tissue disorders do you see in disorders of primary hemostasis?
- ehlers Danlos syndrome
- abnormalities of collagen or elastin
- vascular bleeding, articular hypermobility, dermal hyperelasticity, tissue fragility
what is waldenstrom macroglobulinemia?
- vascular damage from sludging of hyperviscous blood
- can also cause platelet functional abnormalities
what can amyloidosis do to vessels?
- can cause vessel damage
what diseases are encompassed by rickettsial and meningococcal diseases?
- rocky mountain spotted fever and meningococcemia
- involve vascular endothelium -> necrosis and rupture of small vessels
define: thrombocytopenia
A decrease in the number of platelets in the blood.
list the different causes of thrombocytopenia
1. irradiation, exposure to drugs/chemicals
2. acute leukemia
3. myelophthisis
4. aplastic anemia
5. spelnic sequestration
6. multiple transfusions
7. DIC
8. idiopathic thrombocytopenic purpura (ITP)
9. thrombotic thrombocytopenic purpura (TTP)
what are general considerations for thrombocytopenia? what are it's dominant features and characteristics?
- petechial cutaneous bleeding, intracranial bleeding, oozing from mucosal surfaces
- decreased platelet count
- prolonged bleeding time
what do you see in bone marrow aspiration when thrombocytopenia is caused by 1) decreased platelet production, and 2) increased platelet destruction?
1) decreased megakaryocytes
2) increased megakaryocytes
how does acute leukemia cuase thrombocytopenia?
- decreased production of platelets b/c of replacement of BM by blast cells
how does myelophthisis cuase thrombocytopenia?
- decreased production of platelets b/c of BM replacement by tumor cells
what causes aplastic anemia?
- exposure to toxic agents (e.g. benzene).
- can also be due to autoimmune destruction by cytotoxic T cells
what is aplastic anemia?
The term 'aplastic' means the marrow suffers from an aplasia that renders it unable to function properly. Anemia is the condition of having fewer red blood cells than normal, or fewer than needed to function properly. Typically, anemia refers to low red blood cell counts, but aplastic anemia patients have lower counts of all three blood cell types: red blood cells, white blood cells, and platelets.
what does splenic sequestration result in?
- decreased levels of circulating platelets
why do you get thrombocytopenia with multiple transfusions?
- dilution of blood
how does DIC cause thrombocytopenia?
- depletion of platelets
for which diseases can thrombocytopenia occur secondarily to?
- AIDS
- SLE
what is idiopathic thrombocytopenic purpura (ITP)?
- aka immune or autoimmune thrombocytopenia purpura
- antiplatelet antibodies coat and damage platelets -> removed by spleenic macrophages
what is the progression of idiopathic thrombocytopenia purpura in children?
- usually acute, self-limiting reaction to viral infection or immunization
what is the progression of idiopathic thrombocytopenia purpura in adults?
- chronic disorder
how do yu get fetal thrombocytopenia?
- maternal IgG antibodies in affected mothers
how do you diagnose idiopathic thrombocytopenia purpura?
- diagnosed based on thrombocytopenia with normal or increased megakaryocytes, no known exposure to thrombocytopenic agents, and lack of palpable spenomegaly
what are the characteristics of thrombotic thrombocytopenic purpura (TTP)
- platelet-derived hyaline microaggregates in small vessels
- thrombocytopenia
- micrangiopathic hemolytic anemia
- helmet cells and schistocytes
- transient neurologic abnormalities
- renal insufficiency
- fever
what RBC shapes do you get when RBCs squeeze through narrow vessels?
- helmet cells
- schistocytes
what are some causes of thrombotic thrombocytopenic purpura (TTP)?
- deficiency of von Willebrand factor (vWF) metalloprotease (ADAMTS 13) -> accumulation of high-molecular-weight multimers of vWF -> platlet microaggregate formation
how are platelet functional abnormalities different from thrombocytopenia?
- these disorders have a normal platelet count
- can result in mucocutaneous bleeding and are associated with prolonged bleeding time
what are the causes of platelet functional abnormalities?
1. defects of platelet adhesion
- von Willebrand disease
- Bernard-Soulier disease
2. defects in platelet aggregation
- aspirin-induced
- glanzmann thrombasthenia
what is Bernard-Soulier disease?
- autosomal recessive
- unsually large platelets
- lack fo platelet surface glycoprotein (GPIb-IX-V) needed for platelet adhesion
how does aspirin impair platelet aggregation?
- induces acetylation and inactivation of COX-1 and COX-2 -> failure to synthesize platelet aggregant: thromboxane A2
what is glanzmann thrombasthenia?
- inability of platelets to aggregate due to hereditary deficiency in platelt surface GPIIb-IIIa
- required for formation of fibrinogen bridges between platelets
where do you see GPIb-IX-V and GPIIb-IIIa deficiencies?
- bernard-soulier disease
- Glanzmann thrombasthenia
what are disorders of seconadary hemostasis caused by?
- deficiencies of plamsa clotting factors in the coagulation cascade
what are the manifestations of disorders of secondary hemostasis?
- bleeding from larger vessels -> hemarthroses -> large hematomas -> large ecchymoses -> extensive bleeding with trauma
define: ecchymosis
A small bruise caused by blood leaking from broken blood vessels into the tissues of the skin or mucous membranes.
what is not affected in disorders of secondary hemostasis?
- bleeding time
- platelet count
what tests are abnormal in disorders of secondary hemostasis?
- PT
- APTT
- PTT
- thrombin time
what does an abnormal PT test tell you?
- deficiency in fibrinogen
- deficiency in factors II, V, VII, and X
what does an abnormal APTT or PTT tell you?
- deficiencies of all the coagulaiton factors except for VII and XIII
what does an abnormal thrombin time test tell you?
- deficiency of firbinogen
what is classic hemophilia? what are the genetics behind it?
- aka hemophilia A, factor VIII deficiency
- X-linked disorder
- severe cases have less than 1% residual factor VIII activity
what are some characteristics of classic hemophilia?
- bleeding into muscles, subcutaneous tissues, and joints
- associated with long APTT (or PTT)
- normal bleeding time, platlet count, PT and thrombin time
how do you correct a prolonged APTT as seen in classic hemophilia?
- addition of normal plasma
what is christmas disease
- aka hemophilia B, factor IX deficiency
- incidence is 1/5 that of classic hemophilia
- INDISTINGUISHABLE from classic hemophilia in mode of inheritance and clinical features
what causes vitamin K deficiency?
- caused by fat malabsorption (pancreatic or small bowel disease)
how does vit K deficiency present in neonates?
- hemorrhagic disease of the newborn, which is due to deficiecy exoenous vit K in breast milk with INCOMPLETE intestinal colonization by vit-K synthesizing bacteria
what are the abnormal test results for Vit K deficiency?
- decreased clotting factors II, VII, IX, and X
- prolonged PT and APTT
list some combined primary and secondary hemostatic defects
1. von Willebrand disease
2. DIC
3. Coagulopathy of liver disease
4. Dilutional coagulopathy
what causes von Willebrand disease?
- deficiency of vWF, a multimeric protein synthesized by endothelial cells and megakaryocytes
what is the epidemiology/genetics of von Willebrand disease?
- most common hereditary bleeding disorder
- autosomal
what produces vWF?
- endothelial cells and megakaryocytes
what is vWF?
- a carrier protein for factor VIII (the antihemophilic factor)
- the two proteins circulate together as a complex
- mediates adhesion of platelets to subendothelium at sites of vascular injury
what does vWF interact with at sites of vascular injury?
- subendothelium and the platelt-surface glycoprotein complex GPIb-IX-V
what are characteristics of von Willebrand disease (test results)
* impaired platelet adhesion
- prolonged bleeding time
* functional deficiency of factor VIII
what does impaired platelet adhesion caused by von Willebrands disease cause?
- deficiency platelet plug formation -> hemostatic bleeding and prolonged bleeding time
what does a deficiency of factor VIII caused by von Willebrands disease cause?
- caused by a deficit of vWF, the carrier protein for VIII
- will get secondary hemostatic bleeding and prolonged APTT
describe DIC
- widespread clotting with resultant consumption of platelts and coagulation factors, esp II, V, VIII, and fibrinogen
what are the clinical manifestations of DIC?
- thrombotic phenomena
- hemorrhage
what are the blood characteristics seen in DIC?
- microangiopathic hemolytic anemia with schistocytes
- increased fibrin and firbinogen degredation
- thrombocyptopenia
- prolonged bleeding time, PT, APTT, and thrombin time
- microthrombi in the small vessels of many organs
what causes DIC?
- release of tissue thromboplastin (tissue factor)
- activation of teh intrinsic pathway of coagulation
- secondary activation of the fibrinolytic system
when is DIC most often seen?
- obstetric complications: toxemia, amniotic fluid emboli, retained dead fetus, abruptio placentae
- cancer (lung, pnacrease, prostate, stomach)
- infection (gram-neg sepsis)
- trauma
- immunologic mechanisms (e.g. immune complex disease or hemolytic transfusion reactions)
what is abruptio placentae?
- premature separation of the placenta
what is coagulopathy of liver disease? how does it arise?
- arises because all coagulation factors except vWF are produced in the liver
- as hepatocellular damage increases, the PT, APTT, and thrombin time are prolonged
- prolonged bleeding time due to platelt functional defects and overt thrombocytopenia
how do you correct for coagulopathy of liver disease?
- vit K derivatives -> carboxylation of glutamyl residues of precursors of factors II, VII, IX, and X
what is dilutional coagulopathy?
- mutiple transfusions of stored blood deficient in platlets and factors II, V, and VIII
- will get persistent bleeding from surgical wounds
- can result in thrombocytopenia or prolonged PT or APTT