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LHT2 > Platelet disorders DSA > Flashcards

Platelet disorders DSA Flashcards

1
Q

thrombocytopenia- caused by 2 conditions

A
  • dec prod of platelets

- inc destruction/sequestration of platelets

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2
Q

thrombocytosis caused by 2 conditions

A
  • overprod of platelets (essential thrombocythemia)

- inc platelet released from marrow/storage areas in response to an infl stimulus (reactive thrombocytosis)

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3
Q

Decreased platelet production

A
  • bone marrow failure
  • bone marrow infiltration
  • chemotherapy and irradiation
  • nutritional deficiencies
  • cyclic thrombocytopenia
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4
Q

Thrombocytopenia due to bone marrow failure

A
  • congenital- fanconi anemia, Wiskott-aldrich syndrome

- acquired- aplastic anemia, MDS

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5
Q

Increased platelet destruction

A
  • immune thrombocytopenia
  • thrombotic microangiopathy
  • HIT
  • DIC
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6
Q

Immune thrombocytopenia- essentials of diagnosis

A
  • isolated thrombocytopenia
  • asses for any new causative medications and HIV and Hep C infections
  • dx of exclusion
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7
Q

ITP- treatment

A
  • corticosteroids with IVIG or WinRho (anti-D)
  • platelet transfusions can be given if active bleeding is present
  • anti-B cell ab rituximab
  • splenectomy
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8
Q

Thrombotic microangiopathy

A
  • TTP and HUS
  • thrombocytopenia due to incorporation of platelets into thrombi and microangiopathic hemolytic anemia (shearing of erythrocytes in fibrin networks)
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9
Q

TTP

A

-autoab’s against ADAMTS-13- accum of vWF multimers- aggregate platelets

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10
Q

HUS

A
  • classic- caused by E coli (shiga toxin)

- atypical- leads to acute kidney injury- defects in proteins that reg complement activity

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11
Q

thrombotic microangiopathy- pentad of sx’s

A

-microangiopathic hemolytic anemia, thrombocytopenia, fever, kidney disease, neuro system abnormalities

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12
Q

thrombotic microangiopathy- tx

A

-plasma exchange- mortality rate is 95% w/o tx

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13
Q

Heparin induced thrombocytopenia

A

-IgG ab’s to heparin-platelet factor 4 complexes- activates platelets- leads to thrombocytopenia and a pro-thrombotic state

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14
Q

HIT- essentials of dx

A
  • thrombocytopenia within 5-14 days of exposure to heparin
  • decline in baseline platelet count of 50% or greater
  • thrombosis occurs in up to 50% of cases; bleeding is uncommon
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15
Q

DIC- essentials of dx

A
  • frequent cause of thrombocytopenia in hospitalized pts
  • prolonged activated partial thromboplastin time and prothrombin time
  • thrombocytopenia and dec fibrinogen levels
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16
Q

Other conditions causing thrombocytopenia

A
  • drug-induced
  • posttransfusion purpura
  • von willebrand dz type 2B
  • platelet sequestration
  • pregnancy
  • infection or sepsis
  • pseudothrombocytopenia
17
Q

posttransfusion purpura

A
  • sudden onset thrombocytopenia in a pt who had received transfusion of red ces, platelets, or plasma within 1 wk
  • ab’s against the human platelet antigen PlA1
  • either multiparous women or persons who have received transfusions previously
  • admin of IVIG
18
Q

platelet sequestration

A

-splenomegaly may lead to thrombocytopenia

19
Q

pregnancy

A

-expansion of the blood volume- leads to hemodilution

20
Q

Qualitative platelet disorders

A
  • Bernard-Soulier Syndrome
  • Glanzmann thrombasthenia
  • storage pool diseases
  • acquired- medications
21
Q

Congenital disorders of platelet fxn- essentials of dx

A
  • usually dx in childhood
  • FH usually positive
  • may be diagnosed in adulthood when there is excessive bleeding
22
Q

Bernard-Soulier syndrome

A
  • rare, autosomal recessive

- reduced or abnormal platelet memb expression of glycoprotein Ib/IX (vWF R)

23
Q

Glanzmann thrombasthenia

A
  • abnormality in glycoprotein IIb/IIIa R’s on the platelet membrane, which are required to bind fibrinogen and vWF, both which bridge platelets during aggregation
  • autosomal recessive
24
Q

storage pool disease

A

-defects in the release of alpha or dense platelet granules

activated platelets release the contents of plt granules to reinforce the aggregatory response normally

25
Q

Bernard-Soulier syndrome- lab findings

A
  • abnormally large platelets, moderate thrombocytopenia, prolonged bleeding time
  • plt aggregation studies show a defect in response to ristocetin (response to other agonists is normal)
  • dx confirmed by platelet flow cytometry
26
Q

Glanzmann thrombasthenia- lab findings

A

-platelet aggregation studies show marked impairment of aggregation in response to stimulation with typical agonists

27
Q

storage pool disease- lab findings

A
  • gray platelet syndrome- defects in alpha granules, thrombocytopenia, and marrow fibrosis
  • albinism-associated- defective dense granules
  • non-albinism-associated- seen in Ehlers-Danlos, Wiskott-Aldrich syndrome
28
Q

Qualitative platelet disorders- tx

A

-transfusion of normal platelets

29
Q

Essential Thrombocytosis- essentials of dx

A
  • elevated platelet count in absence of other causes
  • normal red blood cell mass
  • absence of BCR/ABL gene
30
Q

Essential Thrombocytosis- path

A
  • prolif of megakaryocytes in the bone marrow

- JAK2 mutations

31
Q

Essential Thrombocytosis- sx and signs

A
  • 50-60 yo
  • most common clinical problem- thrombosis
  • erythromelalgia- painful burning of hands
32
Q

Essential Thrombocytosis- lab findings

A

-elevated plt count- hallmark

33
Q

Essential Thrombocytosis- must be distinguished from?

A

secondary causes of an elevated plt count!

  • reactive thrombocytosis- plt count seldom exceeds 1,000,000
  • infl disorders and chronic infection can cause elevations in platelet count
34
Q

Essential Thrombocytosis- tx

A

oral hydroxurea

LHT2 (17 decks)

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