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M2 Heme/Onc > 1/6 Platelet and Bleeding Disorders - Carr > Flashcards

1/6 Platelet and Bleeding Disorders - Carr Flashcards

1
Q

quantitative vs qualitative platelet disorders

A

quantitative: low platelet count

qualitative: right number of platelets but incorrect fx

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2
Q

thrombocytopenia

A

low platelet count

  1. decreased production (marrow issue)
  • congenital (rare)
  • acquired (infection, meds, alcohol, marrow failure, bone marrow infiltration)
  1. increased destruction (decr half life)
  2. sequestration
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3
Q

neonatal immune thrombocytopenias

A
  1. neonatal autoimmune thrombocytopenia
  • maternal SLE or ITP
  • passive transfer of maternal IgG
  • tx: IVIG
  1. neonatal isoimmune (NATP)
  • incopatibility of fetal and maternal platelet antigens
  • most commonly P1A1
  • high risk of recurrence with future pregnancy
  • tx: maternal platelets, IVIG
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4
Q

nonimmune platelet destruction

A

mechanical platelet destruction

  • microangiopathic hemolytic anemia
  • disseminated intravascular coag
  • TTP: thrombotic thrombocytopenia purpura
    • congenital absene or antibody to VWF protease ADAMTS13
  • HUS: hemolytic uremic syndrome
    • E. Coli 0157:H7
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5
Q

DIC

A

disseminated intravascular coagulation

“consumptive coagulopathy”

  • pathological activation of coag
  • initated by formation of small clots inside blood vessels throughout the body
    • clots consume available coag proteins, anticoags, and platelets
    • resulting acquired deficiency in clotting proteins and platelets → abnormal bleeding

causes

  • conditions that introduce TF in circulation (trauma, cancer, obstetrical complications)
  • endothelial damage
  • stagnant blood flow
  • infection

lab (Pathoma)

tx

  • treat underlying disease
  • replete consumed factors
  • heparin (in acute promyelocytic leukemia, thrombosis)
  • ATIII concentrates
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6
Q

TTP

cause

pentad

A

thrombotic thrombocytopenia purpura

cause: ADAMTS13 deficiency/absence

  • normally ADAMTS13 cleaves vWF into smaller monomers for degradation
  • uncleaved multimers (in TTP) → abnormal platelet adhesion
  • can be genetic (rare, auto recessive deficiency) or acquired (antibody against protein, usually in adulthood)

pentad of TTP

  1. thrombocytopenia
  2. microangiopathic hemolytic anemia
  3. CNS disturvance
  4. renal failure
  5. fever

see…

  • thrombocytopenia
  • schistocytes
  • elevated LDH

80% of patients die if not treated

  • replace ADAMTS13
  • remove circulating andibody
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7
Q

HUS

A

hemoytic uremic syndrome

E. Coli 0157:H7 (fecal contamination of food)

looks v similar to TTP

  • no neuro features
  • bloody diarrhea
  • renal failure dominates
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8
Q

ddx: TTP vs DIC

3 tests and diff outcomes

A

coagulation screens

  • TTP: normal
  • DIC: abnormal

fibrinogen level

  • TTP: normal
  • DIC: low

fibrin split (degradation) products

  • TTP: minimal/no elevation
  • DIC: elevated
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9
Q

sequestration as a cause of thrombocytopenia

key sign

A

key: enlarged spleen w low platelet count

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10
Q

qualitative defects

disorders of adhesion

A

primary defect in platelet-vesselwall interaction

  1. Bernard Soulier syndrome: GP1b deficiency (platelet receptor for vWF)
  2. von Willebrand disease
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11
Q

vWF

types of von Willebrand disease

A

von Willebrand factor

  1. binds platelet GP1b
  2. binds collagen
  3. binds and stabilizes factor VIII

types of disease

  1. deficiency of vWF (types 1, 3)
  • partial deficiency (Type 1), 70-80% of all cases
  • severe/complete def (Type 3)
  1. dysfx protein (type 2)
  • improper assembly of protein (2A)
  • change of binding to platelet Gp1b (2B, 2M)
  • decr factor VIII binding (2N)

enhanced binding of vWF by platelet

2A, 2B, 2N are key

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12
Q

disorders of aggregation

primary defects in platelet-platelet interaction

A
  1. congenital afribrinogenemia: absence of plasma fibrinogen
  2. Glanzmann thrombasthenia: deficiency/defect in GPIIb/IIIa
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13
Q

disorders of storage granules

A
  1. disorders of alpha-granules
  • gray platelet syndrome: absence of alpha granules
  • Paris-Trousseau (Jacobsen syndrome): giant alpha granules
  • arthrogryposis-renal dysfx-cholestasis: deficiency in alpha granules
  1. deficiencies of dense granules
  • Hermansky Pudlak syndrome: absence of dense bodies, mutations of HPS gene
    • common in Puerto Rico
    • oculocutaneous albinism, variable bleeding, ceroid accumulation (intestines, lungs, kidneys)
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14
Q

idiopathic dense granule disorder

A

“storage pool disease”

  • attributed to defect in dense granules on basis of platelet aggregation and release studies
  • prob most common platelet defect
  • possibly defect of intracellular signaling
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15
Q

coagulation disorders

hemophilia

A

1. hemophilia A: factor VIII deficiency

2. hemophilia B: factor IX deficiency (aka Christmas disease)

X linked

  • hallmark: bleeding into muscles and joints (ankles, knees; starts after crawling/walking age)
  • can present in infancy

tx: recombinant or endogenous factor replacement
* issue: INHIBITORS: neutralizing antibodies against infused factor product

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16
Q

factor XI deficiency

A

“hemophilia C”

autosomal recessive

common in Ashkenazi Jewish pops

mucocutaneous bleeding (not muscle or joint)

17
Q

factor XIII deficiency

A

extremely rare

lack of fibrin cross-linking leads to reduced clot stability and strength

classic presentation in infancy (bleeding from umbilical stump, intracranial hemm)

clinical test: urea clot lysis time

PT and PTT are normal!

18
Q

two acquired factor deficiencies

A
  1. vitamin K deficiency
  • affects II, VII, IX, X
  • causes: antibiotics, malabsorption, hemmorhagic disase of infancy
  • DRUGS: warfarin, coumadin, rat poison
  1. liver disease
  • affects: II, VII, IX, X
  • factors V, fibrinogen
  • factor VIII preserved
19
Q

coagulopathy of liver disease

A
  • decreased clotting factor levels
  • decreased platelets (enlarged spleen/sequestration)
  • decreased natural anticoag
  • abnormal blood vessels: esoph and rectal varices
  • decreased clearance of activated clotting factors
  • decreased clearance of clot breakdown pdts
  • production of abnormal fibrinogen
20
Q

mixing studies

A

help differentiate whether prolonged PTT is due to deficiency or inhibitory antibody

21
Q

look at slides 117-120

TFPI

A

tissue factor pathway inhibitor

controls extrinsic pathway

22
Q

antiphospholipid antibodies

A

phsopholipid is added to tube as part of PTT assay

ab which cross reacts with phospholipid in PTT will cause prolongation → mixing study will stay prolonged

23
Q

deficiencies of controlling proteins increase the risk of thrombosis

4 ex

A

antithrombin deficiency

protein C deficiency

protein S deficiency

TFPI deficiency

24
Q

purpura fulminans

A

severe protein C deficiency

  • presents within hours of birth: unmeasurable PC
  • rapid progression to DIC
  • purpuric lesions at pressure points → palpable black eschars
  • often blind infants from vitreal vein clot
  • prenatal arterial ischemic stroke
25
Q

inherited predisposition to thrombosis

A

Factor V Leiden : resistant to to inactivation by APC

prothrombin 20210A

M2 Heme/Onc (16 decks)

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