Platelet Function Testing Flashcards
Designed to detect qualitative (function) platelet
abnormalities in patients with symptoms of mucocutaneous bleeding.
Platelet Function Testing
REMINDER‼️‼️‼️‼️
Platelet count and blood film is reviewed before the test.
Original platelet function test, now obsolete.
Bleeding Time Test
Bleeding time testing
First described by __________ and. _______________
Duke (1912) and modified by Ivy (1941)
Platelet adhesion, aggregation and secretion are assessed using ___________________
in-vitro platelet aggregometry
an instrument designed to measure platelet
function in a suspension of Citrated WB or PRP.
Aggregometer
Samples use in aggregometer
Citrated WB - 3.2% sodium citrate ( 18-24°C)
Platelet Rich Plasma- Platelet count must be (200-300 x 10^9/ L)
Types of Platelet Aggregometry Studies
- Optical platelet aggregometry
- Whole blood platelet aggregometry
- Platelet Lumiaggregometry
Optical platelet aggregometry sample used
PRP
Optical platelet aggregometry testing principle
Light transmittance aggregometry
Baseline 0% Transmission scales down to 100% transmittance.
Optical platelet aggregometry
Optical platelet aggregometry
5 Phases
- Baseline
- Shape Change
- Primary-wave aggregation
- ADP/ATP release
- Second-wave aggregation
Whole blood platelet aggregometry
- Sample used
Whole blood (WB)
Whole blood platelet aggregometry
Testing principle
Electrical impedance
Whole blood platelet aggregometry
Working temp:
37 c
As platelet aggregate, platelets collects on the electrodes impeding the current. The change is amplified and recorded.
Whole blood platelet aggregometry
Platelet Lumiaggregometry
- Sample used:
Whole blood (WB) or PRP
Platelet Lumiaggregometry
Testing principle
Chemiluminescence
Platelet Lumiaggregometry
Working temp
37 C
What reagent is added in platelet lumiaggregometry
Luciferin-luciferase enzyme (Reagent)
Luciferin-luciferase enzyme (Reagent) work
oxidized by ATP which generates proportional chemiluminescence.
Agonist Used In Aggregometry
- Thrombin
- ADP
- Epinephrine
- Collagen
- Arachidonic acid
- Ristocetin
biphasic curves
- Thrombin
- ADP
- Epinephrine
monophasic curves
- Collagen
- Arachidonic acid
- Ristocetin
Thrombin receptor
PAR-1,PAR-4;
GPIba & GPVI
ADP receptor
P2Y1 & P2Y12
Epinephrine receptor
A2-Adrenergic receptor
Relatively unaffected by membrane disorders or
enzyme deficiencies.
Thrombin
Most commonly used agonist.
ADP
Cannot induce aggregation in storage pool disorders
Epinephrine
Collagen receptor
GPIa/IIa & GPVI
Arachidonic acid receptor
TPa and TPb
Ristocetin receptor
GPIb/IX/V with vWF
