platelet aggregation measurement; platelet function analysis (PFA-100)
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Indications
- personal or family history of mucocutaneous or postsurgical bleeding[2]
* rapid screening of platelet function, has replaced bleeding time test
Contraindications
- routine preoperative screening[2]
Clinical significance
- see bleeding time
- effects of aspirin on platelets are irreversible
- effects of other NSAIDs on platelets are reversible
Specimen
Procedure
- citrated platelet-rich plasma is continuously stirred in a platelet aggregometer with a light beam passed through the suspension
- platelet aggregation in response to added chemical stimulus is then monitored by changes in light transmittance.
- a discoid to spheroidal shape change is seen as an initial decrease in transmittance & the subsequent platelet clumping allows more light to pass thus is recorded as an increase in light transmittance
- some instruments are equipped with a 2nd channel to measure release of ATP from platelet dense granules
- this is accomplished by addition of firefly luminescence substrate & enzyme (luciferin & luciferase) to the platelet-rich plasma
- released ATP functions as a cofactor for light emission by luciferase
- the emitted light is recorded by a 2nd photodetector
- reagents used to stimulate platelet aggregation include:
More general terms
More specific terms
- platelet aggregation ADP induced
- platelet aggregation arachidonate induced
- platelet aggregation calcium ionophore induced
- platelet aggregation collagen induced
- platelet aggregation epinephrine induced
- platelet aggregation norepinephrine induced
- platelet aggregation ristocetin induced
- platelet aggregation serotonin induced
- platelet aggregation thrombin induced
- platelet aggregation thrombin receptor activating peptide-6 induced
Additional terms
References
- ↑ Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 705
- ↑ 2.0 2.1 2.2 Medical Knowledge Self Assessment Program (MKSAP) 16, 18. American College of Physicians, Philadelphia 2012, 2018.
- ↑ Panel of 5 tests Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0030160.jsp
- ↑ Favaloro EJ, Lippi G, Franchini M. Contemporary platelet function testing. Clin Chem Lab Med. 2010 May;48(5):579-98 PMID: https://pubmed.ncbi.nlm.nih.gov/20148722