3-PRIMARY HEMOSTASIS PART 2 Flashcards by Dave U.

What is the principle behind the Platelet Adhesiveness Test or Glass Bead Retention Test

Platelet adhesion to glass+compare platelet count before and after glass bead exposure

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What is the specimen required for the Platelet Adhesiveness Test

Two whole blood specimens+routine collection+glass bead system into EDTA tube

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What equipment is needed for the Platelet Adhesiveness Test

Vacutainer needle+hypodermic needle+vacutainer holder+EDTA tubes+siliconized adapter+polyvinyl tubing (0.113 inch)+glass beads+siliconized nylon mesh (0.002 inch)+Duco cement+platelet counting materials

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What method is commonly used for the Platelet Adhesiveness Test

Salzman method

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How is the Platelet Adhesiveness Test performed

Two venipunctures+one with glass bead system+one routine+collect blood+count platelets+calculate percent adhesiveness

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What is the formula for percent platelet adhesiveness

(Platelet count without glass beads – Platelet count with glass beads/Platelet count without glass beads) × 100

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What is the normal value range for platelet adhesiveness

26% to 60%

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What conditions are associated with decreased percent platelet adhesiveness

Glanzmann Thrombasthenia+Von Willebrand Disease+Chediak-Higashi Syndrome+myeloproliferative disorders+uremia+aspirin and other drugs

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What conditions are associated with increased percent platelet adhesiveness

Venous thrombosis+pulmonary embolism+carcinoma+pregnancy+splenectomy+oral contraceptives

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What is the main function assessed by platelet aggregometry and lumiaggregometry

Platelet adhesion+aggregation+secretion

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What is the principle of platelet aggregometry

Platelet aggregation measurement+light transmittance/electrical impedance

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What is the principle of lumiaggregometry

Aggregation measurement+ATP secretion+chemiluminescence

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What specimen is required for light transmittance platelet aggregometry

Platelet-rich plasma+200

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What specimen is required for whole blood aggregometry and lumiaggregometry

3.2% sodium citrate whole blood+1:1 saline dilution

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How should specimens for platelet aggregometry be stored

18-24°C+no chilling+test within 3-4 hours

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What are common agonists used in platelet aggregometry

Thrombin+TRAP+ADP+epinephrine+collagen+arachidonic acid+ristocetin

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How is light transmittance aggregometry performed

PRP+stir bar+37°C incubation+agonist+light transmittance monitoring

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How is whole blood platelet aggregometry performed

Saline-diluted whole blood+electrodes+impedance measurement

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How does lumiaggregometry detect platelet secretion

ATP release+Luciferin-luciferase reaction+light emission measurement

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What is the principle of whole-blood platelet aggregometry

Electrical impedance measurement+platelet aggregation increases impedance

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What specimen is used for whole-blood platelet aggregometry

1:1 saline-whole blood suspension+300-500 µL

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How is whole-blood platelet aggregometry performed

WB suspension in cuvette+stir bar+37°C incubation+add agonist+insert electrodes+record impedance

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What does increased platelet aggregation indicate in impedance aggregometry

Increased electrical impedance

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What is the principle of platelet lumiaggregometry

Simultaneous measurement of aggregation (impedance)+ATP secretion (chemiluminescence)

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What specimen is used for platelet lumiaggregometry

Platelet-rich plasma or whole blood

How is platelet lumiaggregometry performed

Sample+luciferin-luciferase reagent+agonist+monitor aggregation and ATP secretion+measure luminescence

What does increased ATP secretion indicate in lumiaggregometry

Increased chemiluminescence

What are typical normal ranges for aggregation and ATP secretion

Aggregation: 1-31 Ω+ATP secretion: 0.0-2.0 nM (varies by agonist)

What are common agonists used in whole-blood aggregometry and lumiaggregometry

Thrombin+TRAP+collagen+ADP+arachidonic acid+ristocetin

What is the role of ADP in platelet aggregation

Most common agonist+induces biphasic aggregation+causes shape change+secretion+relies on G-proteins/eicosanoid pathway

What receptors does ADP bind on platelets

P2Y1+P2Y12

What signaling pathways are involved in ADP-induced platelet activation

G-proteins+eicosanoid synthesis pathway

What is the typical ADP concentration for aggregation testing

1-10 µM+produces biphasic curve (primary/secondary aggregation)

What drugs inhibit ADP-induced aggregation

P2Y12 inhibitors+clopidogrel+prasugrel+ticagrelor

What is the biphasic aggregation curve with ADP

Primary aggregation (reversible)+lag phase+secondary aggregation (irreversible

What storage conditions are required for ADP reagent

-20°C or -70°C storage+reconstituted with saline immediately before use

What does decreased secretion in response to ADP indicate

Platelet membrane disorders+eicosanoid pathway defects+ASA/NSAID/clopidogrel therapy

What is the role of epinephrine in aggregometry

Binds α2-adrenergic receptor+no effect in whole-blood aggregometry/storage pool disorders/eicosanoid defects

How is epinephrine stored

1°C to 6°C+reconstituted with distilled water immediately before use

What is the role of collagen in aggregometry

Binds GPIa/IIa+GPVI+induces monophasic curve with lag phase+requires intact receptors/G proteins/eicosanoid pathway

What does abnormal collagen-induced aggregation indicate

Membrane defects+storage pool disorders+aspirin use

How is collagen stored

1°C to 6°C+no freezing

What is the role of arachidonic acid in aggregometry

Assesses eicosanoid pathway+monophasic curve+affected by aspirin/NSAIDs

How is arachidonic acid stored

-20°C or -70°C in dark+diluted with bovine albumin

What is the role of ristocetin in aggregometry

Assesses VWF function+induces agglutination+used in VWD diagnosis

What VWF tests are included in standard panels

VWF antigen (VWF:Ag)+Factor VIII assay+VWF:Rco+RIPA assay

What methodologies are used for VWF:Ag

Enzyme immunoassay (EIA)+latex immunoassay (LIA)+chemiluminescence (CLIA)

What is the VWF:Rco assay

Measures platelet agglutination using ristocetin+replaced by automated LIA/CLIA

What is RIPA assay

Qualitative test using PRP+ristocetin (1mg/mL)+abnormal in VWD/BSS

What are additional VWF activity assays

REAADS VWF activity immunoassay+VWF collagen binding assay (CBA)

What type of thrombocytopenia occurs after heparin exposure and carries thrombotic risk

Heparin-associated thrombocytopenia (HAT/HIT)

What detects heparin-dependent platelet antibodies in patient plasma

HIT functional assay (platelet aggregation test)

What specimen is collected 24 hours post-heparin for HIT testing

Citrated plasma (1:9 AC:WB) + donor plasma

What instrument measures platelet aggregation in HIT testing

Platelet aggregometer

What reagent must match the heparin type administered to the patient

Test heparin

What indicates a positive HIT result

>20% aggregation in heparin-exposed cuvette

What cuvette combination confirms HIT with patient's own platelets

0.2 mL patient PPP + 0.3 mL patient PRP + heparin

What platelet count must PPP have in HIT testing

<10

What test measures platelet surface activity for clotting factors

Platelet Factor 3 (PF3) availability test

What stimulates PF3 release in the assay

Kaolin + epinephrine

What specimen is used for PF3 testing

Citrated whole blood

What reagent triggers clot formation in PF3 testing

Calcium chloride (CaCl₂)

What platelet concentration is required for PF3 testing

50 × 10⁹/L

What indicates normal PF3 availability

Clotting time of 37–51 seconds (PRP at 50 × 10⁹/L)

What corrective step is taken if patient PPP has abnormal clotting time

Dilute PRP with control PPP

What confirms heparin-independent aggregation in HIT testing

Aggregation in control cuvettes (#1

What is added to cuvettes #1 and #3 in HIT testing

Heparin working solution (10 U/mL)

What is added to cuvettes #2 and #4 in HIT testing

Saline (negative control)

What is the general appearance of platelets under phase contrast microscopy

Dark against light background

What test uses a pressure cuff and counts petechiae in a 1-inch diameter area on the volar/dorsal arm/hand

Rumpel-Leede test

What is the procedure for Quick’s capillary fragility test

Apply cuff at mid systolic-diastolic pressure for 5 minutes+count petechiae in 5 cm ring

What is the normal range for petechiae in Quick’s method

0–5 petechiae in a 5 cm ring

What indicates capillary fragility in Quick’s method

>5 petechiae

What pressure and duration are used in Gothlin’s method

35 mm Hg for 15 minutes on both arms

How are petechiae counted in Gothlin’s method

Multiply total petechiae on both arms by 2

What is the normal range for petechiae in Gothlin’s method

0–8 petechiae

What is considered equivocal in Gothlin’s method

8–12 petechiae

What indicates capillary fragility in Gothlin’s method

>12 petechiae

What is the principle of the suction test/Petechiometer method

Negative pressure (200 mm Hg) causes blood extravasation+measures permeability

What is the normal range for petechiae in the suction test

0–2 petechiae at 200 mm Hg

What is considered equivocal in the suction test

4–8 petechiae (requires retesting on another site)

What indicates capillary fragility in the suction test

>8 petechiae