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Hematology Part 2 (bleeding) (Disorders of the clotting cascade…

- - - - mechanism/pathophysiology
        
        and is due to a deficiency in the protease ADAMTS-13, which cleaves the high-molecular-weight multimers of vWF, decrease in ADAMTS-13 activity leads to accumulation of clumps of ultra-large-molecular-weight vWF multimers, which bind to masses of platelets, leading to microvascular occlusion and thrombocytopenia. Schistocytes form as erythrocytes are damaged by these tangles of vWF and platelets
      - medications
        
        quinine, ticlopidine, cyclosporine, and gemcitabine
      - treatment
        
        plasma exchange, FFP
      - indication for transfusion
        
        if plt <10,000, otherwise don't because it can make the situation worse
      - different from HUS
        
        fever, kidney disease, neurologic findings, or abdominal pain.
        
        inciting factors
        
        Escherichia coli O157:H7
    - - tends to be secondary Initial therapy with glucocorticoids should be initiated with either prednisone, 1 mg/kg followed by a slow taper over the course of weeks, or dexamethasone, 40 mg/d for 4 days, given every 2 to 4 weeks. Following a course of glucocorticoids, 25% of patients respond and never relapse,
    - - scoring system
        
        4T's
      - treatment
        
        stop heparin products and start direct Xa inhibitors (abaroxiban)
      - pathophysiology
        
        the heparin/Platelet Factor 4 complex can activate platelets via Fc receptors on platelets
      - once HIT is diagnosed, then what is important to do
        
        Baseline Doppler ultrasound studies of all four extremities should be obtained, because the risk of thrombosis in HIT is more than 30%
- - - - nosebleeds in children, easy bruising, bleeding gums, and postsurgical bleeding. Gynecologic problems are especially common
    - - PF100 test (prolonged), aPTT (Factor 8 -decreased)
    - - Desomepressin
  - - - elevated PT (consumption of factor 7) - shortest half-life
        
        possible elevation of PTT (if other factors are being consumed)
        
        decreased fibrinogen level
        
        elevated D-dimer or FSP
        
        low platelets
        
        Microangiopathic hemolytic anemia
  - - - factor 8
    - - factor 9
    - - prolongation of the aPTT with a normal PT, and the aPTT mixing study will fully correct.
    - - Bethesda titer, which is a measure of the strength of the inhibitor
        would not correct with aPTT (anti 8)
  - - - Bleeding into muscles and joints
- - - - pathophysiology
        
        mutation of G1691A in factor V leads to resistance to cleavage by Protein activated Protein C
      - test
        
        factor V leid APC resistance assay
    - - inheritance
        
        AD
      - mechanism for increased DVT
        
        increased circulating Factor 2
      - test
        
        PCR testing/prothrombin gene
    - - mechanism
        
        inhibiting thrombin/ activated Factor 10, 9
    - - AD inheritance, lack of activated protein C leads to inability to inactivate protein 5, 8
    - - cofactor for APC,
  - - - Vascular events (either thrombosis, 3 or more AB/one premature before 34 due to vascular issues/ one or more unexplained after the 10th week with normal fetal morphology
      - laboratory req
        
        lupus anticoagulant, anticardiolipid anti b2 glycoprotein (measured separately 12 weeks apart
- - - - aPTT, although anti–factor Xa plasma levels
    - - 60 minutes, on drip - return to baseline in 3-4 hours
    - - protamine
  - - - anti-Xa activity must be measured
    - - don't use if EGFR < 30
  - - - PT/INR
    - - 5 days
- - - - D-dimer?
        
        if negative, then you are done, if positive then imaging
    - - start with imaging like duplex or CTA
  - - - distal DVT (if only the calf veins are affected) with low risk of progression
      - follow up
        
        serial Doppler ultrasonography approximately 5 to 7 days after initial diagnosis and then 10 to 14 days later is suggested
    - - rivaroxaban and apixaban, no such initial bridging therapy was required, you just need a bolus pack
    - - warfarin for at least 5 days and until the INR is greater than 2 for 24 hours
      - why is this necessary
        
        paradoxically leads to hypercoagulability in the first 5 days of initiation owing to its rapid effect of lowering protein C activity levels
    - - idarucizumab, a reversal agent for dabigatran
    - - NOACs should not be used in patients who have an extreme BMI (>40) or who have kidney disease with a creatinine clearance less than 30 mL/min
    - - provoked - 3-6 months, otherwise it is indefinite
    - - acute pelvic or proximal leg DVT who cannot undergo anticoagulation because of active bleeding or a very high bleeding ris