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Hematology 2 (Lecture) > Laboratory Evaluation of Platelets (F) > Flashcards

Laboratory Evaluation of Platelets (F) Flashcards

1
Q

What is the purpose of quantitative evaluation of PLTs?

A

Measures the # of PLTs per uL of blood

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2
Q

What is the characteristic of quantitative evaluation of PLTs?

A

It should be performed first

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3
Q

What is the purpose of qualitative evaluation of PLTs?

A

Detects PLT structure abnormalities

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4
Q

?What are the characteristics of qualitative evaluation of PLTs?

A

1) Suspected if bleeding symptoms, specifically mucocutaneous bleeding, are present
2) Suspected if PLT ct is > 50,000/uL

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5
Q

What is the purpose of PLT estimate?

A

Verifies the accuracy of released PLT cts from automated machines and obtained PLT cts from manual methods

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6
Q

How is PLT estimate performed?

A

Performed by using an EDTA whole blood in making a Wright-stained peripheral blood film and counting the # of PLTs seen in 10 OIFs

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7
Q

What is PLT ct?

A

It is the # of PLTs in 1 L or 1 uL of peripheral whole blood

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8
Q

How is PLT ct performed?

A

It is performed by adding diluting fluid to a small amt of EDTA whole blood and counting the approx # of PLTs seen in 25 small squares in the central large square of the hemocytometer

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9
Q

What is the normal range (in conventional unit) of PLT ct?

A

150,000 - 400,000/uL

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10
Q

What is the normal range (in SI unit) of PLT ct?

A

150 - 400 X 10^9/L

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11
Q

What is thrombocytosis?

A

Increased / high PLT ct

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12
Q

What is thrombocytopenia?

A

Decreased / low PLT ct

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13
Q

What is the purpose of PLT morphology in blood film?

A

It allows the evaluation of PLT appearance under the microscope

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14
Q

How is PLT morphology in blood film performed?

A

It is performed by using an EDTA whole blood in making a Wright-stained peripheral blood film and taking note of the size, granularity, clumping, and adherence to WBCs (neutrophils)

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15
Q

In PLT morphology in blood film, what is the only parameter that can be correlated w/ automated machine cts?

A

PLT size

Increased / high PLT ct = increased / high mean platelet volume

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16
Q

What are the diff PLT morphologies present in blood film?

A

1) Gray PLTs
2) Giant PLTs
3) Stress PLTs
4) PLT clumps
5) PLT satellitosis
6) Adherence to WBC

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17
Q

How is bleeding time performed?

A

It is performed by counting the duration of bleeding from skin puncture, assessing it at 30 sec interval, and reporting the result in minutes and seconds

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18
Q

When is bleeding time assessed?

A

For every 30 secs interval

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19
Q

What is the manner (or units) of reporting of bleeding time?

A

In minutes and seconds

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20
Q

What are the purposes of bleeding time?

A

1) It evaluates primary hemostasis specifically the PLT function
2) It is used to predict surgical bleeding

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21
Q

At what procedure bleeding time is first described and at what procedure is it modified?

A

First described by Duke; modified by Ivy

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22
Q

What is the characteristic of bleeding time?

A

It is now considered as an obsolete test due to intracapillary pressure, skin thickness, size of wound, and depth of wound

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23
Q

What is the normal range of bleeding time?

A

2 - 4 mins

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24
Q

What is the relationship bet bleeding time and PLT function?

A

Increased / prolonged bleeding time = decreased / low PLT function

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25
Q

What is the relationship bet bleeding time and blood vessel integrity?

A

Increased / prolonged bleeding time = decreased / low blood vessel integrity

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26
Q

What is the purpose of PLT aggregometry?

A

It evaluates PLT aggregation and PLT secretion using citrated PLT-rich plasma or citrated whole blood

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27
Q

How can PLT aggregometry be performed?

A

It can be performed using various methods:

1) Lumiaggregometry
2) Conventional PLT aggregometry

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28
Q

What are the diff PLT agonists?

A

1) Thrombin
2) ADP
3) Ristocetin
4) Collagen
5) Arachidonic acid
6) Epinephrine

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29
Q

What are the actions of thrombin?

A

1) It cleaves protease activatable receptors or PARs, GP Ib, and GP V
2) It also triggers secondary hemostasis within the sx; synthetic thrombin is reco (thrombin receptor-activating peptide)

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30
Q

What is the characteristic of thrombin?

A

It is the 1st agonist added because of its capability to induce full secretion

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31
Q

What is the action of ADP?

A

It binds P2Y1 and P2Y12 receptor

32
Q

What is the characteristic of ADP?

A

It is most commonly used agonist for conventional aggregometry

33
Q

What is the action of ristocetin?

A

It binds GP Ib/IX/V associated with VWF

34
Q

What is the action of collagen?

A

It binds GP Ia/IIa and GP VI

35
Q

What is the action arachidonic acid?

A

It is involved in eicosanoid pathway

36
Q

What is the action of epinephrine?

A

It binds alpha(sign)-adrenergic receptors

37
Q

What is the characteristic of epinephrine?

A

It cannot be used electrical impedance aggregometry

38
Q

How is lumiaggregometry performed?

A

It is performed by adding an agonist to whole blood diluted w/ saline or citrated PLT-rich plasma to measure the aggregation reported in ohms and ATP secretion in nM

39
Q

What should be done if PLT ct is < 100,000/uL in lumiaggregometry?

A

Whole blood sx should not be diluted w/ saline

40
Q

What is the principle followed by lumiaggregometry?

A

It follows the principle of chemiluminescence that uses a firefly-derived luciferin-luciferase rgnt and the result is detected by a photodetector

41
Q

What is the relationship bet luminescence and PLT aggregation?

A

Increased / high luminescence = increased / high PLT aggregation

42
Q

What is the relationship bet luminescence and ATP secretion?

A

Increased / high luminescence = increased / high ATP secretion

43
Q

What is the procedure (or steps) for PLT aggregation?

A

1) 300 - 500 of diluted WB or 500 uL PRP into the cuvette
2) Add 2 - 5 uL agonist directly to the cuvette
3) Add luciferin-luciferase

44
Q

What is the procedure (or steps) for ATP secretion?

A

1) 300 - 500 of diluted WB or 500 uL PRP into the cuvette
2) Add ATP std directly to the cuvette
3) Add luciferin-luciferase

45
Q

How is PRP conventional aggregometry performed?

A

It is performed by adding an agonist to citrated PLT-rich plasma to measure the aggregation reported in ohms

46
Q

What is the principle followed by PRP conventional aggregometry?

A

It follows the principle of light transmittance and the result is detected by a photodetector

47
Q

What happens in PRP conventional aggregometry?

A

More light passes as PLTs continue to aggregate

48
Q

When is PRP conventional aggregometry not performed?

A

It cannot be performed if PLT ct is < 100,000/uL

49
Q

What is the relationship bet light transmittance and PLT aggregation?

A

Increased / high light transmittance = increased / high PLT aggregation

50
Q

What is the process (or steps) of PRP conventional aggregometry?

A

1) 300 - 500 uL of PRP into the cuvette
2) Drop 1 clean plastic stir bar into the cuvette
3) Place cuvette in incubation well
4) Incubate at 37 DC for 5 mins
5) Place cuvette in reaction well
6) Add an agonist directly to the cuvette
7) Turn on the light source

51
Q

How is WB conventional aggregometry performed?

A

It is performed by adding an agonist to whole blood diluted w/ saline to measure the aggregation reported in ohms

52
Q

What should be done if PLT ct is < 100,000/uL (in WB conventional aggregometry)?

A

If PLT ct is < 100,000/uL, whole blood sx should not be diluted w/ saline

53
Q

What is the principle followed by WB conventional aggregometry?

A

It follows the principle of electrical impedance that uses low-voltage cartridge-mounted disposable direct current electrodes and the result is detected by instrument circuitry

54
Q

What happens in WB conventional aggregometry?

A

PLTs coat the electrodes as they continue to aggregate

55
Q

What is the relationship bet electrical impedance and PLT aggregation in WB conventional aggregometry?

A

Increased / high electrical impedance = increased / high PLT aggregation

56
Q

What is the process (or steps) of WB conventional aggregometry?

A

1) 300 - 500 uL of diluted WB into the cuvette
2) Drop 1 clean plastic stir bar into the cuvette
3) Place cuvette in incubation well
4) Incubate at 37 DC for 5 mins
5) Place cuvette in reaction well
6) Add an agonist directly to the cuvette
7) Suspend a pair of electrode into the cuvette

57
Q

What is the disorder that only has normal ristocetin?

A

only ristocetin normal = Glanzmann thrombasthenia

58
Q

What are the actions (lab results) of the GP IIb/IIIa targeting drugs (in GT)?

A

1) PLT aggregation response to ADP: absent
2) PLT aggregation response to collagen: absent
3) PLT aggregation response to epinephrine: absent
4) PLT aggregation response to ristocetin: normal
5) PLT aggregation response to thrombin: absent
6) PLT aggregation response to arachidonic acid: absent

59
Q

What are the disorders that has ristocetin as absent and thrombin as decreased?

A

1) Bernard-Soulier Syndrome

2) Von Willebrand Disease

60
Q

What are the lab results for BSS and VWD?

A

1) PLT aggregation response to ADP: normal
2) PLT aggregation response to collagen: normal
3) PLT aggregation response to epinephrine: normal
4) PLT aggregation response to ristocetin: absent
5) PLT aggregation response to thrombin: decreased
6) PLT aggregation response to arachidonic acid: normal

61
Q

?What is the meaning if collagen is absent?

A

X collagen = X GP Ia/IIa and GP VI receptor

62
Q

?What is the meaning if ADP is decreased?

A

decreased / low ADP = X P2Y12 receptor and P2Y12-targeting drugs

63
Q

?What is the meaning if epinephrine is decreased?

A

Decreased / low epinephrine = X alpha(sign)-adrenergic receptor

64
Q

?What is the meaning if thrombin is decreased?

A

Decreased / low thrombin = X PAR and PAR-targeting drugs

65
Q

?What is the meaning if arachidonic acid is decreased?

A

Decreased / low arachidonic acid = X enzymes of eicosanoid pathway

66
Q

?What is the meaning if ADP, collagen, and epinephrine are all decreased?

A

Decreased / low ADP, collagen, epinephrine = storage pool disorders

67
Q

?What is the meaning if collagen and arachidonic acid are absent?

A

X collagen, arachidonic acid = COX-targeting and NSAID

68
Q

What are the diff PLT activation markers?

A

1) PF4 immunoassay

2) 11-Dehydrothromboxane B2 assay

69
Q

What is the relationship bet plasma PF4 and PLT activation (in PF4 immunoassay)?

A

Increased / high plasma PF4 = increased / high PLT activation

70
Q

How is PF4 immunoassay performed?

A

It is performed by adding small amt of plasma from CTAD whole blood in a microplate

71
Q

What is the principle followed by PF4 immunoassay?

A

It follows the principle of ELISA that uses rgnt Abs to measure the concentration of the target Ag w/c is PF4

72
Q

Elevated plasma PF4 is usually associated w/ what?

A

It is usually associated w/ thrombotic stroke or coronary thrombosis

73
Q

What is the relationship bet 11-dehydrothromboxane B2 and PLT activation?

A

Increased / high 11-dehydrothromboxane B2 = increased / high PLT activation

74
Q

How is 11-dehydrothromboxane B2 assay performed?

A

It is performed by adding small amt of random urine in a microplate

75
Q

What is the principle followed by 11-dehydrothromboxane B2 assay?

A

It follows the principle of ELISA that uses rgnt Abs to measure the concentration of the target Ag w/c is 11-dehydrothromboxane B2

76
Q

What is the characteristic of 11-dehydrothromboxane B2 assay?

A

Thromboxane A2 -> after 30 secs, thromboxane B2 -> w/ liver enzymes, 11-dehydrothromboxane B2

77
Q

What is associated w/ elevated 11-dehydrothromboxane B2?

A

It is associated w/ aspirin failure

Hematology 2 (Lecture) (11 decks)

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