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pathoma > Hemostasis and Related disorders > Flashcards

Hemostasis and Related disorders Flashcards

1
Q

Hemostatis 2 stages:

A

Primary: forms weak platelet pug (platelets and vessel wall)

Secondary - coagulation cascade stabilizes platelet plug

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2
Q

Primary hemostasis (4 steps)

A
  1. transient vasoconstriction of damaged vessel
  2. Platelet adhesion to surface of disrupted vessel
  3. Platelet degranulation
  4. Platelet aggregation
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3
Q

Vasoconstriction of damaged wall mediated by

A

reflex neural stimulation and endothelin release

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4
Q

Platelet adhesion to surface of disrupted vessel

A

vWF binds exposed subendothelial collagen (BM & CT underneath exposed)

Platelets bind vWF using GP1b Receptor

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5
Q

What is vWF derived from

A

Weibel-Palade bodies of endothelial cells and alpha granules of platelets

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6
Q

Platelet degranulation

A

Adhesion induces shape change in platelets and degranulation

ADP release: GP2B/3A receptor expression
TXA2: promotes platelet aggregation

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7
Q

Platelet aggregation

A

Aggregate via GP2B/3A using fibrinogen - forming weak platelet plug

Stablize platelet plug using secondary hemostasis

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8
Q

Disorders of primary hemostasis d/t?

A

abnormalities of in platelets

quantitative or qualitative

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9
Q

Clinical features of primary hemostasis

A

mucosal and skin bleeding

epistaxis, hemoptysis, GI bleeding, hematuria, mehorrhagia

intracranial bleeding w/ severe thrombocytopenia

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10
Q

Skin bleeding symptoms

A

Petechiae, purpura, ecchymoses

Petechiae sign of thrombocytopenia (NOT QUALITATIVE disorders)

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11
Q

normal platelet count

A

150-400K

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12
Q

normal bleeding time

A

2-7 minutes

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13
Q

Immune Thrombocytopenia Purpura

A

AI - IgG against platelet antigens (GP2B/3A)

most common thrombocytopenia of children and adults

Ab produced by plasma cell in spleen - ab bound platelets are consumed by splenic macrophages

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14
Q

Acute Immune Thrombocytopenia Purpura

A

children
after viral infection/immunization

Self limted

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15
Q

Chronic Immune Thrombocytopenia Purpura

A

Adults
Women of child bearing age

Primary/Secondary
Secondary associated with lupus

May cause short-lived thrombocytopenia in offspring - IgG crosses placenta

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16
Q

Lab findings in Immune Thrombocytopenia Purpura

A

Decrease platelet count

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17
Q

Treatment of Immune Thrombocytopenia Purpura

A

Corticosteroids

Adults may relapse

IVIG: when symptomatic bleeding to raise platelet count

Splenectomy (in refractory cases)

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18
Q

Microangiopathic hemolytic anemia cause

A

pathologic formation of platelet microthrombi in small vessels

RBC shear when passing thrombus - lyse and become schistocyte

Platelets are consumed

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19
Q

What are two disorders you seee Microangiopathic hemolytic anemia

A

TPP (thrombocytopenic pupura) - platelet microthrombi - skin bleeding - decrease in ADAMSTS13 which normally cleaves vWF multimers

HUS (Hemolytic uremic syndrome)

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20
Q

TTP d/t decrease in what enzyme?

A

ADAMTS13 - cleaves vWF multimer into smaller monomers for eventual degredation

Large multimers lead to abn platelet adhesion = microthrombi

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21
Q

Who is decreased ADAMTS13 seen in most?

A

adult females (acquired autonantibody)

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22
Q

HUS d/t?

A

Drugs or infection -

children: E coli O157:H7 dysentery (verotoxin damages endothelial cells resulting in platelet microthrombi)

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23
Q

Clinical findings of HUS/TTP

A 
Skin/mucosal bleeding
Microagniopathic hemolytic anemia
Fever
Renal insufficiency (HUS) 
CNS abnromalities (TTP)
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24
Q

HUS/TTP lab findings

A

Thrombocytopenia w/ increased bleeding time
Normal PT/PTT
Anemia w/ schistocytes
Increased megakaryocytes on bone marrow biopsy

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25
Q

TX: HUS/TTP

A

plasmapheresis

Corticosteroids

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26
Q

Qualitative problems of platelets

A
  1. Bernard Soullier syndrome

2. Glanzmann thrombasthenia

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27
Q

Bernard Soulier Syndrome

A

Genetic defect GP1b deficiency

Platelet adhesion impaired

Blood smear; Mild thrombocytopenia and enlarged platelets (immature)

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28
Q

Glanzmann Thrombasthenia

A

Genetic GP2b/3A deficiency

Platelet aggregation impaired

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29
Q

How does aspirin cause qualitative defect in platelets?

A

Irreversibly inhibits COX - so lack of TXA2 impairs platelet aggregation

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30
Q

Uremia disrupts platelet function

A

both adhesion and aggregation impaired

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31
Q

Secondary hemostasis for:

A

stabilizing weak platelet plug

Thrombin converts fibrinogen to fibrin in platelet plug - crosslinked stablizing platelet-fibrin thrombus

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32
Q

Where are coagulation cascade factors produced?

A

Liver in inactive form

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33
Q

Coagulation cascade factors activated by?

A

Exposure to activation factors
Phospholipid surface (of platelets)
Calcium - from platelet granules

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34
Q

Disorders of secondary hemostasis usually d/t

A

factor abnormalities

35
Q

Clinical features of secondary hemostasis disorders

A

Deep bleeding into muscles/joints

Rebleeding after surgical procedures

36
Q

PT measures:

A

extrinsic (VII) and common (II, V, X + fibrinogen)

Prothrombin time

37
Q

PTT measures

A

Intrinisc factors (XII, XI, IX, VIII) and common (II, V, X + fibrinogen)

Partial thromboplasin time

38
Q

Hemophilia A

A

VIII
males - x linked
Can be from new mutation w/o family hx

deep tissue, joint, post surgical bleeding

39
Q

Lab findings in Hemophilia A

A

Increase PTT
Normal PT
Decrease Factor VIII
Normal platelet ct, bleeding time

40
Q

Hemophilia B

A 
IX
ncrease PTT
Normal PT
Decrease Factor IX
Normal platelet ct, bleeding time
41
Q

Coagulation factor inhibitor disorder

A

Acquired ab against coagulation factor - impaired factor function

Anti-F VIII most common

Distinction by mixing study:
Mix with normal plasma - if hemophilia A - PTT will correct

Mix with normal study - inhibitor - PTT will not correct

42
Q

vWB dz

A

Most common inherited coagulation disorder***

most common is AD - decreased vWF levels

Platelet adhesion can’t occur

Mild mucosal and skin bleeding

43
Q

vWB dz lab findings

A

Increased bleeding time
Increase PTT
normal PT
abnormal ristocetin test

44
Q

vWF tx

A

desmopressin - increases vWF release from Weibel Palade bodies

45
Q

why is PTT elevated in vWF?

A

need to stabilze factor 8

46
Q

RIstocetin test***

A

Introduce restocetin - normally causes platelets to aggregate - but in vWF - they don’t

47
Q

VIT K deficiency

A

Vit K gamma carboxylates factors II, VII, IX, X and S

48
Q

VIT K deficiency occurs in?

A

Newborns
Long term antibiotic therapy
Malabsorption

49
Q

Why does liver failure cause abnormal secondary hemostasis

A

decreased production of coagulation factors, decreased activation of VIT K by epoxide reductase

50
Q

Heparin induced thrombocytopenia (HIA

A

platelet destruction secondary to heparin therapy

Fragments of destroyed platelets activate remaining platelets, leading to thrombosis

Heparin forms complex with PF-4

Don’t give coumdin

51
Q

DIC

A

Pathologic activation of coagulation cascade

Widespread microthrombi in ischemia/infarction

Consumption of platelets and factors resulting in bleeding - IV sites and mucosal surface

52
Q

Common causes of DIC

A 
obstetric complications (amniotic fluid)
Sepsis - endotoxins and cytokines
Adenocarcinoma
Acute promyelocytic leukemia
Rattlesnake bite
53
Q

Lab findings of DIC

A 
decreased platelet count
Increased PT/PTT
decreased fibrinogen
Microangiopathic hemolytic anemia
Elevated fibrin split products (D-dimer)
54
Q

DIC tx

A

transfuse blood products and cryoprecipitate

55
Q

Disorders of fibrinolysis

A

D/t plasmin overactivity resulting in excessive cleavage of fibrinogen

tPA cleave plasminogen to plasmin which cleaves fibrin and fibrinogen

Destroys coagulation factors

Blocks platelet aggreation

56
Q

What inactivates plasmin?

A

alpha-2 antiplasmin

57
Q

Examples of excess plamin

A

Radical prostatectomy - release of urokinase activates plasmin

Cirrhosis of liver - reduced alpha-2 antiplasmin production

58
Q

Increased plasmin presents as & lab findings

A

Increased bleeding

Increased PT/PTT - destroys coagulation factors
Increased bleeding time w/ normal platelet count
Increased fibrinogen w/o D dimers (because fibrin thrombi abscent)

59
Q

TX of increased plasmin

A

Aminocaproic acid - blocks activation of plasminogen

60
Q

Thrombus characterized by

A

Lines of Zahn (alternating layers of platelets/fibrin & RBCs)
And
Attachemenet to vessel wall

61
Q

Virchow triad:

A 
Disruption in blood flow
Endothelial cell damage
Hypercoaguable state (common in cancer)
62
Q

Disruption in blood flow examples

A

Immobilization
Cardiac wall dysfunction
Aneurysm

63
Q

How to endothelial cells prevent thrombosis

A
  1. Block exposure to subendothelial collagen & underlying tissue factor
  2. Produce Prostacyclin & NO
  3. Secrete heparin like molecules
  4. secrete tPA
  5. secrete thrombomodulin
64
Q

Causes of endothelial damage

A

Atherosclerosis
Vaculitis
High levels of homocysteine

65
Q

Cystathionine beta synthase (CBS) deficiency

A

High homocysteine levels w/ homocysteinuria

Vessel thrombosis, mental retardation, lens dislocation, long slender fingers

66
Q

Hypercoaguable state

A

Excessive procogaulant or defective anticoagulant proteins

Recurrent DVT as young age

67
Q

Hypercoaguable state causes

A
  1. Protein C/S def
  2. Factor V Leiden mutation
  3. Prothrombin expression increased
  4. ATIII def
  5. oral contraceptives
68
Q

Protein C & S inactivate which factors?

A

V & VIII

69
Q

What can you see with warfarin when pt has protein C/S def?

A

Warfarin skin necrosis (coumidin skin necrosis)

Can’t produce 2, 7, 9, 10, C, S factors when given Warfarin - C& S are first to depelete
Activating 2, 7, 9, 10 so give heparin

If deficient in C & S - very increase risk of hypercoagulable state with 2, 7, 9, 10

70
Q

Factor V Leiden

A

Mutated factor 5 - can’t be cleaved by protein C & S (can’t shut off FV)

Most common inherited cause of hypercoagulable state

71
Q

Prothrombin 20210A

A

Inherited pt mutation in prothrombin

Increased gene expression - prothrombin to thrombrin - converts fibrinogen to fibrin - leads to thrombus

72
Q

Antithrombin III def

A

Decreases protective effect of heparin-like molecules produced by endothelium, increasing risk for thrombus

Heparin admin - PTT in these patients doesn’t rise

73
Q

Oral contraceptives

A

Estrogen induces increased production of coagulation factors

74
Q

Atherosclerotic embolus

A

plaque dislodges - presense of cholesterol clefts

75
Q

Fat embolus

A

long bone fracture, soft tissue damage

dyspnea and petechia on skin overlying chest

76
Q

Gas emoblus

A

Decompression sickness
Nitrogen dissolves in blood - then precipitates out during ascent

Bends/Chokes

77
Q

Chronic gas emoli

A

Caisson dz

Multifocal ishcmeic necrosis of bone

78
Q

Amniotic fluid embolus

A

enters maternal circulation during labor or delivery - lodges in lungs

SOB, neurologic symptoms, DIC

Characterized by Squamous cells & Keratin debris from fetal skin in embolus

79
Q

Pulmonary embolism

A

DVT - femoral, iliac, popliteal veins

disoldge and get thromboembolous

80
Q

Why are most PE’s clinically silent

A

Lung has dual blood supply

Embolus usually small/self resolving

81
Q

Pulmonary infarction clinical signs

A

SOB, hemoptysis, pleurtic chest pain, pleural effusion
V/Q scan shows mismatch - perfusion abn
Spiral CT shows vascular filling defect in lung (blocking blood supply)
LE doppler useful to detect DVT
D-dimer elevated

82
Q

Pulm HTN is d/t what?

A

chronic emboli that are reorganized over time

83
Q

Systemic emobli

A

D/t thromboembolus
Left heart
Occlude flow to organs - commonly LE

pathoma (12 decks)

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