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NL Clotting vs. disorders, Injury Reflex Vasoconstriction Primary Hemostasis -Platelet adherence to ECM via vWF -Platelet shape change -Granule release from Plts -Recruitment via ADP, TXA2 ->aggregation to primary hemostatic plug, Primary Hemostasis -Platelet adherence to ECM via vWF -Platelet shape change -Granule release from Plts -Recruitment via ADP, TXA2 ->aggregation to primary hemostatic plug Coagulation cascade Intrinsic collagen/(-) charge-> XIIa (Hagement Factor) activates XI activates IX, Hemophilia B (Christmas Dz, Factor IX def) -clinically indistinguishable from Hemo. A -X-linked recessive -can be (-)Sx or w/ ass'd hemorrhages -14% have nonfcnal factor IX -PROLONGED PTT, NL PT, bleeding time Dx only based on factor assays Hemophilia A (Factor VIII def)-X-linked recessive -most common heritable dz w/ excess bleeding -VIII is cofactor for X activation -in males and homo. females, even hetero. female -due to 'unfavorable lyonization' -30% w/ no FHx -Clinical severity based on amt of Factor VIII -most of severe pts w/ inversion of DNA or protein fcnal domain alterations, not DNA MANIFESTATIONS-easy bruising, massive hemorr after surgery, trauma -spontaneous hemorr in joints-'hemarthrosis' -bleeding into joints->progressive deformities -NO PETECHIAE -NL bleeding time,NL PT, PROLONGED PTT Tx-factor VIII infusion from human plasma -15% develop ABs against -risk of HIV transmission eliminated, Thrombocytopenia(TCP)- K platelets -spontaneous bleeding ងK plts -post-traumatic bleeding 20K-50K PROLONGED BLEEDING TIME NL PT, PTT Characteristics-bleeding from sm. vessels -at skin, mucosa of GI, GU->petechiae -intracranial bleeding also possible -easy bruising, bleeding gums, nosebleeds -melena, hematuria, excessive menses 4 Cause Categories: 1. Dec. plt production-bone marrow dzs -aplastic anemia, B12/folate def (ineff MegaPO) 2. Dec. plt survival-can be immunologic, mechanical -destroyed via anti-plt AB, immune complex -ABs target GPIIb-IIIa, Ib-IX -eg ITP, drug-induced & HIV thrombocytopenias -Alloimmune thrombocyto w/. transfusions 3. Sequestration-may appear w/ splenomegaly -spleen sequesters 90% plts when enlarged 4. Dilutional-via massive transfusions -plts don't survive ᡐ hrs, so everything else added->dilution of existing plts Thrombocytopenias Drug-Induced-quinine, quinidine, PCNs, thiazides, MeDopa, HEPARIN -in 5% of heparin-receiving pts Type I-most pts, rapid onset, insignificant -due to plt-agg effects of heparin Type II-more sever, 5-14 d after starting Tx -life-treatening aa, vv thromboses -immune rxn against heparin:plt factor 4 -ABs deplete, yet activate plts via IgG x-link Discontinue Tx, Primary Hemostasis -Platelet adherence to ECM via vWF -Platelet shape change -Granule release from Plts -Recruitment via ADP, TXA2 ->aggregation to primary hemostatic plug Platelets -temporary plugs 2 types of granules: 1.Alpha granules-P-selectin, fibrinogen, fibronectin, factor V, vWF, platelet factor 4, PDGF, TGF-b 2. Dense bodies/delta granules-ADP, ATP, Ca++, histamine, serotonin, epinephrine Exposed ECM->COLLAGEN, proteoglycans, fibronectin/GPs, Thrombocytopenia(TCP)- K platelets -spontaneous bleeding ងK plts -post-traumatic bleeding 20K-50K PROLONGED BLEEDING TIME NL PT, PTT Characteristics-bleeding from sm. vessels -at skin, mucosa of GI, GU->petechiae -intracranial bleeding also possible -easy bruising, bleeding gums, nosebleeds -melena, hematuria, excessive menses 4 Cause Categories: 1. Dec. plt production-bone marrow dzs -aplastic anemia, B12/folate def (ineff MegaPO) 2. Dec. plt survival-can be immunologic, mechanical -destroyed via anti-plt AB, immune complex -ABs target GPIIb-IIIa, Ib-IX -eg ITP, drug-induced & HIV thrombocytopenias -Alloimmune thrombocyto w/. transfusions 3. Sequestration-may appear w/ splenomegaly -spleen sequesters 90% plts when enlarged 4. Dilutional-via massive transfusions -plts don't survive ᡐ hrs, so everything else added->dilution of existing plts Thrombocytopenias Thrombotic Microangiopathies: -both w/ hyaline thrombi in microvasc (dense plts & fibrin) -plt aggs lead to TCP -thrombi->microangiopathic hemo anemia, organ dysfcn -CAUSE-endoth injury, intravasc thrombosis activation Tx-80% survival after plasma exchange Pt, PTT NL - unlike DIC Thrombotic Thrombocytopenic Purpura (TTP) -pentad:fever, TCP, microangiopathic hemolytic anemia, transient neuro deficits, renal failure -prodrome like influenza, so viral infx probable cause Hemolytic-Uremic Syndrome (HUS) -microangiopathic hemolytic anemia, TCP, NO neuro Sx -childhood onset, DOMINANT renal failure -E.coli O157:H7 verotoxin dmg endoth->HUS after bloody diarr, Extrinsic Tissue Injury ->Tissue Factor (Thromboplastin) activates VII (Tissue Factor) activates IX IXa(+VIIIa) and VIIa Hemophilia B (Christmas Dz, Factor IX def) -clinically indistinguishable from Hemo. A -X-linked recessive -can be (-)Sx or w/ ass'd hemorrhages -14% have nonfcnal factor IX -PROLONGED PTT, NL PT, bleeding time, Primary Hemostasis -Platelet adherence to ECM via vWF -Platelet shape change -Granule release from Plts -Recruitment via ADP, TXA2 ->aggregation to primary hemostatic plug von Willebrand Dz One of most common inherited bleeding d/o -1% frequency; AUTO DOMINANT -more common than hemo A(?), ᡌ variants CLINICAL-spon bleeding from mucosa -excessive bleeding from wounds -menorrhagia -PROLONGED BLEEDING TIME w/ NL plt count -reduced plasma vWF (via RISTOCETIN cofactor activity) -2ndary dec. in VIII levels (b/c vWF stabilizes) ->prolonged PTT -NO BLEEDING INTO JOINTS 2 Major Categories: 1. Type 1, Type 3-REDUCED vWF 1-auto dom, 70% of vW dz 3-auto rec; VERY low vWF, severe clinical -gene deletions, frameshift mutations 2.Type 2-25%; qualitative defects in vWF Subtype 2A most common-auto dom -missense mut->ABNL vWF -mild-moderate bleeding, Primary Hemostasis -Platelet adherence to ECM via vWF -Platelet shape change -Granule release from Plts -Recruitment via ADP, TXA2 ->aggregation to primary hemostatic plug von Willebrand Dz Factor VIII-vWF complex -mostly vWF multimers (from endoth cells, megas) -vWF mostly facilitaties plt adherence -thru Ib-IX, IIb-IIIa, collagen, heparin -stabilizes VIII as well (12 hr half-life vs 2.4) -VIII mostly made by hepatocytes -Ristocetin aggregation test-binds plts -activates vWF receptors->agg if enough vWF, Primary Hemostasis -Platelet adherence to ECM via vWF -Platelet shape change -Granule release from Plts -Recruitment via ADP, TXA2 ->aggregation to primary hemostatic plug Coagulation cascade Secondary Hemostasis -fibrinogen(soluble)->fibrin(insol) -Thrombin-Thrombin Receptors