PLATELET FUNCTION TEST

Question 1

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

Answer 1

Platelet Function Test

Question 2

Platelet count and blood film is reviewed before the test

Answer 2

Platelet Function Test

Question 3

Original platelet function test, now obsolete

Answer 3

Bleeding Time Test

Question 4

First described by Duke (1912) and modified

Answer 4

Ivy (1941) bleeding time

Question 5

Normal Platelet Function:

Answer 5

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

Question 6

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

Answer 6

in-vitro platelet aggregometry

Question 7

measure platelet function in a suspension of citrated WB or PRP

Answer 7

Aggregometer

Question 8

Concentration of Sodium citrate tube

Answer 8

3.2% blue top tube

Question 9

Platelet Rich Plasma – Plasma count:

Answer 9

200 x 300 x 10^9/L

Question 10

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

Answer 10

4 hours of collection

Question 11

Types of platelet aggregometry

Answer 11

1. Optical Platelet Aggregometry
2. Whole Blood Aggregometry
3. Platelet Lumi Aggregometry

Question 12

Optical Platelet Aggregometry Sample:

Answer 12

Platelet Rich Plasma

Question 13

Optical Platelet Aggregometry Principle:

Answer 13

Light Transmittance Aggregometry

Question 14

Optical Platelet Aggregometry Working temp:

Answer 14

37C

Question 15

Baseline 0% Transmission scaled down to 100% transmittance

Answer 15

Optical Platelet Aggregometry

Question 16

4 PHASES of Optical Platelet Aggregometry:

Answer 16

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

Question 17

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

Answer 17

discoid to spherical
degree of shape change

Question 18

Whole Blood Aggregometry
Sample:
Principle:

Answer 18

Whole Blood
Electrical impedance

Question 19

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

Answer 19

Whole Blood Aggregometry

Question 20

Platelet Lumi Aggregometry Sample:

Answer 20

Both WB & PRP

Question 21

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

Answer 21

Platelet Lumi Aggregometry

Question 22

Platelet Lumi Aggregometry Principle:

Answer 22

Chemiluminescence

Question 23

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

Answer 23

Luciferin-luciferase enzyme

Question 24

Biphasic Curve

Answer 24

Thrombin
ADP
Epinephrine

Question 25

Monophasic Curve

Answer 25

Collagen Arachidonic acid Ristocetin

Question 26

Thrombin receptors

Answer 26

PAR-1, PAR4; GPIba & GPVI

Question 27

ADP receptors:

Answer 27

P2Y1 & P2Y12

Question 28

Epinephrine receptors:

Answer 28

A2- Adrenergic receptor

Question 29

Collagen receptors:

Answer 29

GPIa/GPIIa & GPVI

Question 30

Arachidonic acid receptors:

Answer 30

TPa and TPb

Question 31

Ristocetin receptors :

Answer 31

GPIb/IX/V with vWF

Question 32

Relatively unaffected by membrane disorders or enzyme deficiencies

Answer 32

Thrombin

Question 33

Has the disadvantage that is often triggers coagulation simultaneously with aggregation

Answer 33

Thrombin

Question 34

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

Answer 34

Thrombin

Question 35

Most commonly used agonists particularly in aggregometry

Answer 35

ADP

Question 36

Primary aggregation: involves shape change with formation of microaggregates

Answer 36

ADP

Question 37

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

Answer 37

ADP

Question 38

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

Answer 38

Epinephrine

Question 39

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

Answer 39

Collagen

Question 40

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

Answer 40

Collagen

Question 41

Assess platelet eicosanoid synthesis pathway

Answer 41

Arachidonic acid

Question 42

No lag phase used to check for eicosanoid synthesis deficiencies

Answer 42

Arachidonic acid

Question 43

For the diagnosis of BSS and vWD

Answer 43

Ristocetin