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Boards 23' > Hematology > Flashcards

Hematology Flashcards

1
Q

1st line of defense against bleeding

A

vasoconstriction; occurs in response to endothelial damage; key mediator: endothelins (blockers are used in pulmonary HTN)

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2
Q

Activated protein factors in the coagulation cascade

A

activated forms have an “a” added to their Roman numeral ex: 1a, Va, Xa

become *serine proteases

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3
Q

Thrombin

A

factor IIa; thrombin can make more thrombin via positive feedback ex: activates V, XI and VIII - a way to amplify the coagulation cascade

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4
Q

Factor VIII

A

produced in endothelial cells (not liver like other factors); circulates bound to vonWillebrand Factor; released in response to injury

VIII-vWF

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5
Q

Extrinsic Xase

A

TF bearing cells (injury), enzyme: Factor VIIa and Factor X as a substrate

all require phospholipids and calcium

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6
Q

Intrinsic Xase

A

platelets, enzyme: Factor IXa, co factors VIII and substrate Factor X

all require phospholipids and calcium

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7
Q

Calcium in the coagulation cascade

A

considered Factor IV and is REQUIRED for clot formation; activated platelets release Ca2+

NOTE: EDTA binds Ca2+ in blood samples and prevents clotting

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8
Q

Factor XII

A

aka Hageman factor
can activate factor XI
importance is for testing of coagulation system b/c it is activated by contact w negative charges (expose to silica)

basis for partial thromboplastin time (PTT)

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9
Q

Prekallikrein Deficiency

A

rare condition that results in MARKEDLY prolonged PTT due to an inability to activate XII normally (cannot activate bradykinin), but there are NO BLEEDING problems

usually comes known when pt has an abnormal PTT test

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10
Q

Coagulation Inhibitors

A

Antithrombin III
Proteins C and S
TF pathway inhibitor

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11
Q

Antithrombin III

A

a serpin (inhibitor of serine proteases); produced by the liver and activated by endothelium (make heparin sulfate molecules) - basis of the role of: heparin drug therapy

Deficiency = hyper coagulable state

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12
Q

Protein C and Protein S

A

glycoproteins synthesized in the liver as a zymogen (inactive) and activated into activated Protein C (APC) by thrombomodulin; works to primarily inactivate factors Va and VIIIa

Deficiency = hyper coagulable state

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13
Q

Tissue Factor pathway inhibitor

A

inactivates Xa via two mechanisms:

directly binds Xa
Binds TF/FVIIIa complex which then prevents X activation

plasma levels are increased when heparin is administered

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14
Q

Plasminogen activators

A

Tissue plasminogen activator (tPA) and urokinase; activated by streptokinase

used in therapy for acute MI and stroke

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15
Q

Primary Fibrinolysis

A

rare condition where plasmin is overactive; causes increased FDP with normal D-dimer
“hyperfibrinolysis” - no clot to cross linked fibrin means no products of breakdown = no D-dimers

plasmin can deplete clotting factors (similar to DIC) there will be increased PT/PTT w bleeding

seen in pts w prostate cancer: release of urokinase to cirrhosis: loss of alpha2 antiplasmin

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16
Q

Vitamin K

A

required for the synthesis of many clotting factors: II, VII, IX, X, C and S

Deficiency = bleeding
Warfarin is a vitamin K antagonist; pts on warfarin who take antibiotics that target gram (-) can develop supra therapeutic INR due to disruption of vitamin k producing intestinal flora

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17
Q

Erythrocyte Sedimentation Rate (ESR)

A

increased in inflammatory conditions by “acute phase reactant” ex: Fibrinogen, Ferritin and C-reactive protein (CRP)

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18
Q

Platelets

A

derived from megakaryocytes; do not contain a nucleus, regulated by thrombopoietin (TPO); aid in hemostasis and activated by injury

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19
Q

platelets actions

A

1st - adhesion: to sub-endothelium
2nd - aggregation: platelet-platelet binding
3rd - secretions: release of granule contents

Net result of sealing an opening in the vascular tree

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20
Q

von Willebrand Factor

A

a large glycoprotein synthesized by endothelial cells (in Weibel-Palade bodies) and megakaryocytes (alpha granules); released in vascular injury

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21
Q

3 important functions of VWF

A

1 - carrier protein for Factor VIII
2 - binds platelets to damaged endothelins
3 - binds activated platelets together (aggregation)

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22
Q

Platelet adhesion

A

vascular damage leads to exposed collagen, vWF binds the collagen and then vWF binds GP1b on platelets

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23
Q

Platelet aggregation

A

platelets have already underwent adhesion, now there is platelet activation mediated by GPIIb/IIIa receptor and now they can stick together via binding to fibrinogen or vWF linked to other platelets

Basis for IIb/IIIa receptor blocking drugs - blocks aggregation

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24
Q

Platelet secretion

A

platelets are activated by either binding to collagen or by activating substances

When one platelet is activated it can secrete substances to activate other platelets:

Alpha granules (most abundant) and Dense granules

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25
Q

Alpha granules and Dense granules platelet secretion

A

Alpha granules (most abundant): contain fibrinogen, vWF and platelet factor 4

Dense granules: contain ADP, Ca2+ (required for coagulation cascade) and serotonin

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26
Q

Platelet Factor 4

A

released by alpha granules and binds to endothelial cells

Clinical relevance: Heparin induced thrombocytopenia (HIT) - rare life-threatening effect of heparin admin when antibodies are formed against PF4-heparin complexes; screening test - serotonin release assay

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27
Q

Adenosine Diphosphate (ADP)

A

released from dense granules of platelets; binds to P2Y1 (Ca2+ release and change in platelet shape) and P2Y12 (platelet degranulation and increase in aggregation)

there are many PsY12 receptor blocking drugs “ADP receptor blockers” : clopidogrel, prasugrel, ticlopidine, ticagrelor = inhibit platelet activity

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28
Q

Thromboxane A2 (TXA2)

A

powerful platelet activator; basis for aspirin therapy

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29
Q

Thromboxane A2 (TXA2)

A

powerful platelet activator; basis for aspirin therapy

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30
Q

Bleeding Time

A

test of platelet function (does not involve coagulation cascade); when prolonged look for explanation that relies within the platelets

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31
Q

Virchow’s Triad

A

endothelial damage
stasis of blood
hypercoagulability

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32
Q

Common hypercoaguable states

A

post-op - involves are three conditions of Virchow’s triad: inflammation after surgery = hypercoaguable, immobile = stasis and surgery = endothelial damage

falls/hip fractures/trauma/long plane flights / malignancy / pregnancy / elevated homocysteine / smoking are hypercoaguable states

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33
Q

nephrotic syndrome with hypercoagulable states

A

loss of anti-clotting factors in the urine; most anti-thrombin III

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34
Q

4 Inherited Thrombophilia’s

A

Factor V Leiden Mutation
Prothrombin gene mutation
Antithrombin deficiency
Protein C/S deficiency

35
Q

Factor V Leiden Mutation

A

abnormal factor V (point mutation); not INACTIVATED by activated protein C (APC) = factor V remains active longer leading to a hypercoagulable state

36
Q

Prothrombin gene mutation

A

prothrombin 20210 gene mutation leading to increases prothrombin levels = hypercoagulable state

37
Q

Antithrombin deficiency

A

inherited due to gene mutations or acquired due to nephrotic syndrome; classically presents as heparin resistance = escalating dose of heparin w/ no/little change in PTT (heparin activates ATIII)

= hypercoagulable state

38
Q

Protein C/S deficiency

A

associated w warfarin skin necrosis; initial warfarin therapy leads to decreased protein C resulting in thrombus of skin tissue = large dark purple skin lesions

39
Q

bone marrow aspirate

A

multiple myeloma; bone marrow aspirate has numerous plasma cells with perinuclear paleness and nuclei w “clock-face” chromatin; limits the generation of targeted immunoglobulins and pt at increased risk for recurrent bacterial infections

40
Q

EPO signal transduction

A

EPO receptor is Janus kinase 2/signal transducer and activator of transcription (JAK2/STAT) signaling pathway which promotes erythrocyte precursor survival and differentiation

41
Q

EPO signal transduction

A

EPO receptor is Janus kinase 2/signal transducer and activator of transcription (JAK2/STAT) signaling pathway which promotes erythrocyte precursor survival and differentiation

42
Q

bone marrow aspirate

A

amyloid light-chain amyloidosis is associated with multiple myeloma and other monoclonal plasma cell dycrasias due to deposition of insoluble immunoglobin light chain fibrils in major organs (kidneys); bone marrow sample with >10% plasma cells is strongly associated with MM

43
Q

pt with persistent fever, fatigue and sore throat

A

infectious mononucleosis, EBV preferentially infects B lymphocytes by binding CD21 and EBV-infected B lymphocytes then activate cytotoxic CD8+; these reactive atypical CD8+ are the primarily immune response to EBV and are observed in peripheral blood smears

44
Q

Dactylitis

A

painful swelling of the hands and feet is a common presentation of sickle cell disease in young children; sickling episodes results in hemolysis which leads to increased indirect bilirubin and lactate dehydrogenase and decreased levels of haptoglobin

45
Q

types of bleeding

A

petechiae and skin bleeding - usually from abnormal platelets

joint and deep tissue bleeding - usually from abnormal coagulation factors

46
Q

types of bleeding

A

petechiae and skin bleeding - usually from abnormal platelets

joint and deep tissue bleeding - usually from abnormal coagulation factors

47
Q

Glanzmann’s Thrombasthenia

A

AR disorder w deficiency of GPIIb/IIIa receptors; pt present w bleeding often epistaxis; blood smear will show isolated platelets (no clumping); there will be absent platelet aggregation

48
Q

Bernard-Soulier Syndrome

A

AR disorder w deficiency of GPIb platelet receptors; results in *large platelets; prolonged bleeding time and thrombocytopenia; epistaxis or menorrhagia (defect in platelet-to-vWF adhesion)

49
Q

Wiskott-Aldrich syndrome

A

immunodeficiency in infants; X linked WAS gene mut needed for T cell *cytoskeleton; triad:
immune dysfunction, decreased platelets and eczema

50
Q

Idiopathic thrombocytopenia purpura (ITP)

A

decreased platelet survival due to anti-GPIIb/IIIa antibodies; there will be consumption by splenic macrophages

think about what can be causing low platelets: is it bone marrow suppression (not enough being produced) or splenic consumption (dying too early)

51
Q

Thrombotic thrombocytopenic purpura (TTP)

A

disorder (def of ADAM13 - acquired antibody) of small vessel thrombus formation; consumes platelets which leads to thrombocytopenia; vWF multimers that are normally broken down by ADAM13 are released and obstruct flow (impaired cleavage of vWF); blood smear will show shistocytes due to shearing of RBCs

PT/PTT normal (unlike DIC)

Symptoms: fever, neurological (HA, confusion, seizures), renal failure and petechiae and bleeding

52
Q

Hemolytic Uremic Syndrome

A

commonly seen in children followed by GI infection w E. coli 0157:H7 (shiga-like toxin causes microthrombi) - leads to platelet rich thrombi that deposits in small vessels, typically the kidney (think of TTP that only focuses on the kidney)

53
Q

Disseminated Intravascular Coagulation (DIC)

A

widespread activation of clotting cascade; there is diffuse thrombi (platelets/fibrin) leading to obstructive blood flow and ischemia; consumption of clotting factors and platelets; occurs secondary to another process (emergencies and sepsis - endotoxin, malignancies, rattlesnake bites - contain thrombin-like glycoproteins)

presents as bleeding; elevated PT/PTT/thrombin time, low platelets, low fibrinogen, elevated D-dimer

54
Q

ITP, TTP, HUS, DIC

A
55
Q

Uremia

A

renal dysfunction leading to bleeding; uremia toxins floating around in the plasma prevents the platelets from working properly resulting in prolonged bleeding time; there is a normal platelet count and normal coagulation testing

56
Q

Platelet level that bleeding occurs

A

Normal platelet count: 150,000 to 400,000
bleeding occurs when <10,000

57
Q

von Willebrand Disease

A

most common bleeding disorder: AD def in vWF; synthesized by endothelial cells and megakaryocytes; carrier for factor VIII and bonds platelets to endothelium (exposed collagen)

*menorrhagia

labs: normal platelet count, normal PT, increased PTT (factor VIII) and increased bleeding time

test: ristocetin cofactor assay - binds vWF

tx: vWF, desmopressin (increases vWF and factor VIII) and aminocapoic acid (inhibits plasminogen activation - less breakdown of formed clots)

58
Q

Heyde’s Syndrome

A

GI bleeding associated w aortic stenosis; def of vWF due to his shearing forces of aortic stenosis leading to uncoiling of vWF multimers and now cleavage site for ADAMS13 is exposed (now overactivation of ADAMS13) breaking down vWF and now less sufficient

increased risk of angiodysplasia

59
Q

Desmopressin therapy in von Willebrand Disease

A

vWF enhances clotting through both augmentation of platelet binding and stabilization of factor VIII; pts w vWD are deficient of VWF and present w increased bruisability and prolonged mucosal bleeding; desmopressin can alleviate bleeding through endothelial release vWF

60
Q

Antiplatelets

A

blocks the formation of activated platelets
Aspirin
IIb/IIIa inhibitors (activated platelets)
phosphodiesterase inhibitors

61
Q

Anticoagulants

A

blocks the formation of fibrin
Heparin
Warfarin
Direct Thrombin inhibitors
Factor Xa inhibitors

62
Q

Thrombolytics

A

breakup thrombus clots that have already been formed
tPA
Urokinase
Streptokinase

63
Q

Aspirin

A

Antiplatelet agent that inhibits the formation of thromboxane A2 via COX inhibition resulting in decreased platelet activation

indicated in coronary disease and stroke

adverse effects: bleeding, ulcers, tinnitus (alters cochlear nerve function); Reye’s syndrome (liver failure and encephalopathy) not given to children except Kawasaki

64
Q

Thienopyridines

A

anti platelet drugs: ticlopidine, clopidogrel, prasugrel

irreversible P2Y12 receptor blockers; used in aspirin allergy; major adverse effect of bleeding and rare and dangerous effect of TTP (antibodies to ADAMS13)

65
Q

Ticagrelor

A

anti platelet drug similar to the Thienopyridines but REVERSIBLE antagonist of P2Y12 receptor; unique side effect of dyspnea; not associated with TTP

66
Q

phosphodiesterase inhibitors (PDE inhibitors)

A

anti platelet drugs that inhibit phosphodiesterase III in platelets PDE functions to break down cAMP; so there will be increased cAMP leading to decreased platelet activation (ADP is activator of platelets)

two drugs: dipyridamole and cilostazol

Side effects: HA, flushing and hypotension (all due to vasodilation effects)

67
Q

Dipyridamole

A

phosphodiesterase inhibitor (PDE inhibitor) that inhibit phosphodiesterase III in platelets; also a blocker of adenosine uptake which raises the adenosine levels leading to vasodilation; used in stroke prevention and cardiac stress testing

Side effects: HA, flushing and hypotension (all due to vasodilation effects)

68
Q

cilostazol

A

phosphodiesterase inhibitor (PDE inhibitor) that inhibit phosphodiesterase III in platelets; also raises cAMP in vascular smooth muscle; used in peripheral arterial disease

Side effects: HA, flushing and hypotension (all due to vasodilation effects)

69
Q

IIb/IIIa inhibitors

A

anti platelet drugs: Abciximab, eptifibatide and tirofiban

bind and block IIb/IIIa on platelets

unique side effect: thrombocytopenia (monitor platelet count)

69
Q

IIb/IIIa inhibitors

A

anti platelet drugs: Abciximab, eptifibatide and tirofiban

bind and block IIb/IIIa on platelets

unique side effect: thrombocytopenia (monitor platelet count)

70
Q

Heparin

A

anticoagulant that is naturally found in *mast cells; used in two forms:
unfractionated (varying polymers) and low molecular weight (smaller polymers only)

71
Q

unfractionated heparin

A

anticoagulant that activated anti-thrombin III (inactivates multiple clotting factors); increased PTT (intrinsic pathway)

HeparIN = INtrinsic (PTT)

highly variable dose from pt to pt so *dose must be adjusted; long term use can lead to osteoporosis

reversible agent for OD: protamine

72
Q

protamine

A

reversible agent for unfractionated heparin overdose; less effective w LMWH; used in cardiac surgery (high dose heparin admin for heart-lung bypass and a quick reversal is needed at completion of case)

for fasted reversal use fresh frozen plasma

73
Q

Heparin and Thrombocytopenia

A

many pts see a mild (10-20%) drop in platelets = “non-immune” thrombocytopenia BUT there can be an immune-mediated reaction called Heparin-induced thrombocytopenia (HIT) occurs 5-10 days after; immune complexes bind platelet factor 4-hepain (type II hypersensitivity) IgG and PF4 complexes - arterial/vein thrombosis

74
Q

Low molecular weight heparin (LMWH)

A

only the small polymers of heparin; more effective for activating anti-thrombin III to inhibit factor Xa; have very predictable effect w/o having to titrate and monitor PTT and adjust dose

75
Q

Low molecular weight heparin (LMWH)

A

only the small polymers of heparin; more effective for activating anti-thrombin III to inhibit factor Xa; have very predictable effect w/o having to titrate and monitor PTT and adjust dose

if monitoring is required: check anti Xa levels EXCEPT in obesity and renal failure pts

76
Q

Factor Xa inhibitors

A

Rivaroxaban and Apixaban
used in a-fib as alternative to warfarin; do not require PT/INR; can increase PT and PTT

reversal agent: andexanet alfa = inactive “decoy” of Xa that binds drug

77
Q

Direct Thrombin Inhibitors

A

Hirudin, lepirudin, bivalirusin, desirudin, argatroban, and dabigatran

prolong PT, PTT and thrombin time *only UF heparin and DTI’s prolong thrombin time;

78
Q

Dabigatran

A

a direct thrombin inhibitor; an oral alternative to warfarin; commonly used in a-fib; do not require PT/INR monitoring unlike warfarin

reversal agent: idarucizumab = anti-dabigatran monoclonal antibody

79
Q

Warfarin

A

vitamin K antagonist; inhibits epoxide reductase (keeps vit k in oxidized form); takes days to achieve its effects; must monitor PT/INR (start heparin if you need acute onset)

*crosses placenta; avoided in pregnancy

Fresh frozen plasma (immediate) reversal of warfarin; protamine - reversal drug

80
Q

Warfarin Skin Necrosis

A

occurs in pt w protein C deficiency; initial exposure of warfarin will decrease protein C and result in thrombosis of skin tissue; large, dark purple skin lesions

81
Q

Parvovirus B19

A

Unenveloped DNA virus that replicates in RBC progenitor cells; decreases erythropoiesis; in chronic hemolysis pts (Sickle cell, hereditary spherocytosis and beta thalassemia major) watch for “aplastic crisis”

classic scenario: worsening anemia with LOW (corrected) reticulocyte count

82
Q

Glycoprotein IIb-IIIa disorder

A

no problem in aggregation for vWD

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