HEMATOLOGY - platelet disorders + TRA Flashcards

EXAM 2 content

1
Q

what are thrombocytes? what can they do?

A

thrombocytes = platelets
- irregularly shaped anuclear cytoplasmic fragments = not true cells
- needed for blood coagulation + control bleeding
- an injury to a blood vessel –> plates release adhesive proteins, coagulation & growth factors
- plates can assume different shapes + form extensions –> increase surface area & plug vascular openings to control bleeding – main component in primary hemostasis

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2
Q

what is the normal thrombocyte concentration in the blood?

A

150,000 - 400,000 platelets/mm3
- 1/3 platelets are pulled into spleen

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3
Q

what is thrombocytopenia? what kinds of risks can happen with lower level of plates?

A

thrombocytopenia = low plate count
- < 150,00 plates
- < 50,000 –> risk of hemorrhage w minor trauma
- 10,000 - 15,000 –> risk of spontaneous bleeding w/o trauma (mucous membranes like gums + nose bleeding, petechiae, ecchymosis, purpara)
- < 10,000 –> risk of severe spontaneous bleeding (fatal on GI, resp, or CNS)

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4
Q

what are the threshold for platelet transfusions?

A
  • actively bleeding = transfused to keep plate counts of 50,000+ plates
  • pt w/ thrombocytopenia needs surgery = transfused prior, increased to at least 50,000
  • pts w/ below 10,000 –> transfused to prevent spontaneous bleeding
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5
Q

what is petechiae, ecchymosis, & purpura?

A
  • petechiae = pinpoint round spots on skin bc of bleeding
  • ecchymosis = bruising (escaped blood from tissues or ruptured blood vessels)
  • purpura = patches of purple discoloration (from blood into skin + mucous membranes)
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6
Q

what are causes of thrombocytopenia, decreased platelet production?

A
  • viruses: EBV, rubella, CMV, HIV
  • drugs: thiazides, estrogens, quinine-containing drugs, chemo agents, ethanol
  • nutritional deficiencies: vit b12 or folic acid
  • chronic renal failure
  • cancer
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7
Q

what are causes of thrombocytopenia, increased plate consumption? (these are what are are focusing on)

A
  • heparin induced thrombocytopenia (HIT)
    -immune thrombocytopenia purpura (ITP)
  • thrombotic thrombocytopenic purpura (TTP)
  • disseminated intravascular coagulation (DIC)
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8
Q

what is heparin induced thrombocytopenia (a type of increased plate consumption)? cause? character? diagnosis? treatment?

A

a immune mediated reaction to heparin (unfraction or low molecular weight)
- results from: forming antiplatelet antibodies (plate activation + consumption)
- characterized by: precipitous drop in platelet count + venous/arterial thrombosis might occur bc of prothrombotic state
- diagnosis: blood test for anti-heparin platelet factor 4 antibodies

treatment:
- stop all forms of heparin, never give again –> check allergy list
- give direct thrombin inhibitors (ARGARTROBAN) – another anticoagulant

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9
Q

what is immune thrombocytopenia purpura (a type of increased plate consumption)? cause? manifestations? treatment?

A
  • acute: antigen forms immune complexes with circulating antibody –> bind to receptors on plates –> destruction in spleen
  • chronic: IgG autoantibodies against plate specific antigens – autoantibodies bind to platelet antigens –> antibody coated platelets removed from blood by macrophages in spleen
  • clinical manifestations: petechiae, purpura, epistaxis & risk of severe bleeding

treatment:
- glucocorticoids: suppress immune responses & prevent sequestering + further destruction of spleen
- intravenous immune globulin (IVIG): increases plate count by interfering with phagocytosis of antibody coated platelets by macrophages (for chronic)
- splenectomy: plates are in or by the spleen

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10
Q

what are the drugs that can be a treatment for ITP (immune thrombocytopenia purpura)? what is the over class? which one is the exemplary? what do they do?

A

Thrombopoietin Receptor Agonists (TRAs) – stimulate production of platelets
- ROMIPLOSTIM (Nplate) – exemplary
- AVATROMBOPAG (Doptelet)
- ELTROMBOPAG (Promacta)

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11
Q

what is the mechanism of action of ROMIPLOSTIM?

A

ROMIPLOSTIM is a peptibody (combo of peptide & antibody) –> mimics thrombopoietin –> stimulates megakaryocytes – cells that become platelets

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12
Q

what are the therapeutic uses of ROMIPLOSTIM?

A

only AFTER traditional ITP treatments have failed

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13
Q

what are the adverse effects of ROMIPLOSTIM?

A
  • arthralgia, dizziness, insomnia, pain in extremities, abdominal pain, myalgia, shoulder pain, dyspepsia, & paraesthesias

uncommon but serious:
- bone marrow fibrosis = bone forming cells replaced by fibrotic tissue
- hematologic malignancy – from stimulation of bone marrow cells
- thrombotic/thromboembolic complications – from excessive platelet production

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14
Q

what are the contraindications/precautions when taking ROMIPLOSTIM?

A

platelet count may drop to pretreatment levels when drug is discontinued

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15
Q

how do we administer ROMIPLOSTIM?

A

SQ

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16
Q

how do we know if ROMIPLOSTIM was effective? when will we see results, peak, & decline?

A

monitor platelet count
- usually rises 4-9 days after a single dose
- peaks at 12-16 days
- decreased by day 28

17
Q

what is thrombotic thrombocytopenic purpura (TTP), a type of increased platelet consumption of thrombocytopenia?

A

where there are blood clots (thrombotic), low plate count (thrombocytopenic) & purple bruises (purpura)

18
Q

what is TTP (thrombotic thrombocytopenic purpura) caused by? results? treatment?

A

caused by: deficiency of enzyme ADAMTS13 – processes von Willebrand factor
- inherited
- acquired: most common, having antibodies –> dysfunction of enzyme

results in: platelet aggregation/clumping + binding to endothelium of blood vessels –>
- vascular occlusion in organs
- jaundice
- purpura
- petechiae
- bleeding
- thrombocytopenia
- hemolytic anemia
- renal failure
- neuro changes

treatment:
- plasma exchange with fresh frozen plasma –> replenishes functional & removes abnormal ADAMTS13
- glucocorticoids: decreases antibody production & acquired forms of TTP

19
Q

what is thrombocythemia? what is there a risk of?

A

thrombocythemia = thrombocytosis
- plates > 450,000 of blood
- essential (primary) thrombocythemia: a defect in bone marrow –> chronic, myeloproliferative neoplasm
- secondary (reactive) thrombocythemia: occurs during inflammatory conditions + excessive production of cytokines
- usually asymptomatic until count passes 1 million
- risk of: thrombosis (intravascular clot formation) & hemorrhage, even if asymptomatic

20
Q

even though thrombocythemia has a risk of thrombosis (clots), how does it still increase of bleeding? (this can be related to DIC too since its part of increase plate consumption, thrombocytopenia)

A

still lots of bleeding bc of a lot of blood clot formation – consuming body’s plates –> not enough plates in bloodstream to control bleeding

21
Q

what are the clinical manifestations of thrombocythemia?

A

microvasculature thrombosis –> ischemia in fingers, toes or cerebrovascular regions
- erythromelalgia: warm congested hands & fees w/ painful burn sensation – common in LE
- headache
- paraesthesia

22
Q

what is the treatment for thrombocythemia?

A

goal: prevent thrombosis or hemorrhage – there is a risk of
- arterial & venous thrombosis
- bleeding

HYDROXYUREA: non alkylating myelosuppressive agent
- suppresses platelet production

low dose ASPIRIN: to alleviate erythromelalgia & transient neurologic manifestations