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HEMATOLOGY 2 :) > PLATELET FUNCTION TEST > Flashcards

PLATELET FUNCTION TEST Flashcards

1
Q

Designed to detect qualitative (function) platelet abnormalities in patients with symptoms of mucocutaneous bleeding

A

Platelet Function Test

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2
Q

Platelet count and blood film is reviewed before the test

A

Platelet Function Test

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3
Q

Original platelet function test, now obsolete

A

Bleeding Time Test

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4
Q

First described by Duke (1912) and modified

A

Ivy (1941) bleeding time

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5
Q

Normal Platelet Function:

A

1.Resting Platelet
2.Tethering
3.Adhesion
4.Shape Change
5.Stable Aggregation
6.Thrombus Formation

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6
Q

Aggregometry- Platelet adhesion, aggregation, and secretion are assessed using

A

in-vitro platelet aggregometry

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7
Q

measure platelet function in a suspension of citrated WB or PRP

A

Aggregometer

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8
Q

Concentration of Sodium citrate tube

A

3.2% blue top tube

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9
Q

Platelet Rich Plasma – Plasma count:

A

200 x 300 x 10^9/L

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10
Q

Citrated WB – 3.2% sodium citrate (18-24C)
Platelet Rich Plasma – Plasma count: 200 x
300 x 10^9/L Both tested within?

A

4 hours of collection

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11
Q

Types of platelet aggregometry

A
  1. Optical Platelet Aggregometry
  2. Whole Blood Aggregometry
  3. Platelet Lumi Aggregometry
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12
Q

Optical Platelet Aggregometry Sample:

A

Platelet Rich Plasma

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13
Q

Optical Platelet Aggregometry Principle:

A

Light Transmittance Aggregometry

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14
Q

Optical Platelet Aggregometry Working temp:

A

37C

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15
Q

Baseline 0% Transmission scaled down to 100% transmittance

A

Optical Platelet Aggregometry

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16
Q

4 PHASES of Optical Platelet Aggregometry:

A
  1. Baseline
  2. Shape Change
  3. Primary-wave aggregation
  4. ADP/ATP release
  5. Second-wave aggregation
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17
Q

Normal: the shape of the suspended platelet changes from_____intensity of light transmittance initially decrease, then increases in proportion to the_____

A

discoid to spherical
degree of shape change

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18
Q

Whole Blood Aggregometry
Sample:
Principle:

A

Whole Blood
Electrical impedance

19
Q

As Platelet aggregate, platelets collect on the
electrodes impeding the current. The change is
amplified and recorded

A

Whole Blood Aggregometry

20
Q

Platelet Lumi Aggregometry Sample:

A

Both WB & PRP

21
Q

Useful for simultaneous measurement of platelet aggregation of and the secretion of adenosine triphosphate from using WB or
PRP

A

Platelet Lumi Aggregometry

22
Q

Platelet Lumi Aggregometry Principle:

A

Chemiluminescence

23
Q

Reagent added is oxidized by ATP which generates proportional chemiluminescence. Particularly sensitive to ATP release. Thrombin is typically the first agonist used because thrombin induces full secretion

A

Luciferin-luciferase enzyme

24
Q

Biphasic Curve

A

Thrombin
ADP
Epinephrine

25
Q

Monophasic Curve

A

Collagen
Arachidonic acid
Ristocetin

26
Q

Thrombin receptors

A

PAR-1, PAR4;
GPIba & GPVI

27
Q

ADP receptors:

A

P2Y1 & P2Y12

28
Q

Epinephrine receptors:

A

A2- Adrenergic receptor

29
Q

Collagen receptors:

A

GPIa/GPIIa & GPVI

30
Q

Arachidonic acid receptors:

A

TPa and TPb

31
Q

Ristocetin receptors :

A

GPIb/IX/V with vWF

32
Q

Relatively unaffected by membrane disorders or enzyme deficiencies

A

Thrombin

33
Q

Has the disadvantage that is often triggers coagulation simultaneously with aggregation

A

Thrombin

34
Q

Diminished thrombin induced secretion-storage pool disease produces maximum
ATP release

A

Thrombin

35
Q

Most commonly used agonists particularly in
aggregometry

A

ADP

36
Q

Primary aggregation: involves shape change with formation of microaggregates

A

ADP

37
Q

Secondary aggregation: is the formation of full platelet aggregates after release of platelet dense granule ADP test for abnormalities of
membrane binding sites and the eicosanoid synthesis pathway

A

ADP

38
Q

Results of aggregation match those of ADP, except that epinephrine cannot induce
aggregation in storage pool disorder or
eicosanoid synthesis pathway defects no matter how high its concentration

A

Epinephrine

39
Q

Loss of response may
indicate membrane
abnormality, secretion
defect or antiplatelet drugs

A

Collagen

40
Q

Induces no primary
aggregation test for
abnormalities of membrane
binding sites and the
eicosanoid synthesis
pathway

A

Collagen

41
Q

Assess platelet eicosanoid
synthesis pathway

A

Arachidonic acid

42
Q

No lag phase used to check for eicosanoid synthesis deficiencies

A

Arachidonic acid

43
Q

For the diagnosis of BSS
and vWD

A

Ristocetin

HEMATOLOGY 2 :) (1 decks)

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