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Mild Bleeding Work-up


Comprehensive platelet aggregation studies are a standard and accepted part of any coagulation work-up following initial screening tests, PT/INR, aPTT and von Willebrand factor testing. Platelet function testing is an important part of the evaluation of common and rare bleeding disorders [1, 2, 3, 8]. Platelet function testing has been a part of clinical laboratory practice since early in the 20th century (8). Machaon Diagnostics measures platelet aggregation by light transmission aggregometry (LTA) which is the current GOLD STANDARD test for measuring platelet function [4, 5, 6, 8]. We test 7 different platelet activators or agonists, some at multiple concentrations, for a total of 11 platelet aggregation tests as part of our comprehensive platelet function assessment. Each agonist is tested individually against platelets suspended in platelet rich plasma environment and at a standardized platelet concentration (250,000 platelets/μL). The concentrations of agonists included in our assessment have been selected from those recommended by platelet aggregation testing guidelines published by the College of American Pathologists (CAP), Clinical and Laboratory Standards Institute (CLSI), North American Specialized Coagulation Laboratory Association (NASCOLA) and the British Society of Haematology[1, 2, 3, 8]. Platelets promote hemostasis by 4 interconnected mechanisms: 1.) adhering to sites of vascular injury or artificial surfaces, 2.) releasing compounds from their granules, 3.) aggregating together to form a hemostatic platelet plug, and 4.) providing a procoagulant surface for activated coagulation protein complexes on their phospholipid membranes [2]. Platelet aggregation testing is performed to assess each of these mechanisms by exposing platelets to stimuli that mimic physiologic situations encountered during vascular injury and hemolytic processes [3]. Since the activation of platelets is a multiphasic reaction involving different membrane bound receptors and intracellular signaling pathways it is essential to test multiple agonists at multiple concentrations. Lastly, there is good correlation between defects in platelet aggregation and bleeding disorders in affected individuals [1, 2, 3, 7, 8].

STAT: < 24 hours (M-F)

Clot-based, LTA, LIA

Draw Tube: Blue Top

Sample Type: Citrated Plasma and Citrated Whole Blood

Specimen Requirements

Sample Type Volume Required Minimum Volume Stability
PREFERRED Citrated Plasma and Citrated Whole Blood Five tubes, 3mL whole blood each (or equivalent volume); Three aliquots, 1mL each (Citrated Plasma) For pediatric minimum, please call (800) 566-3462. See stability of component tests
REJECTION CRITERIA Samples received more than 2 hours after draw for room temperature samples; and thawed in transit, refrozen or clotted sample for frozen samples

General Information

STAT TAT < 24 hours (M-F)
STAT TAT Performance > 90% of results released in 24 hours
ROUTINE TAT < 1 week
NORMAL RANGE Interpretation: Normal

1. Hayward C, Moffat K, Raby A, Israels S, Plumhoff E, Flynn G, Zehnder J. Development of North American consensus guidelines for medical laboratories that perform and interpret platelet function testing using light transmission aggregometry. Am J Clin Pathol 2010;134:955-963.
2. Kottke-Marhcant K and Corcoran G. The laboratory diagnosis of platelet disorders; an algorithmic approach. Arch Pathol Lab Med 2002;126: 133-146.
3. Guidelines on platelet function testing: The British Society for Haematology BCSH Haemostasis and Thrombosis Task Force. J Clin Pathol. 1988;41: 1322-1330.
4. Karon B and Jaben E. Platelet Function; Laboratory methods for evaluating effectiveness of anti-platelet therapy. Clinical Laboratory News. 2011 April;37(4).
5. Lordkipanidze M, Pharand C, Shampaert E, Palisaitis DA, Diodati JG. Evaluation of the platelet count drop method for assessment of platelet function comparison with “gold standard” light transmission aggregometry. Thromb Res 2009 Sep;124(4): 418-422. Epub 2009 Feb 28.
6. White MM, Krishan R, Kueter TJ, Jacoski, MV, Jennings LK. The use of the pint of care Helena ICHOR/Plateletworks and the Accumetrics Ultegra RPFA for assessment of platelet function with GPIIB-IIIa antagonists. J Thromb Thrombolysis 2004 Dec;18(3): 163-169.
7. Jackson S. The growing complexity of platelet aggregation. Blood 2007 June 15;109(12).
8. CLSI. Platelet Function Testing by Aggregometry; Approved Guidelines. CLSI document H58-A. Wayne, PA: Clinical and Laboratory
Standards Institute; Vol. 28 No. 31., 2008.

SAMPLE REPORT Upon request

Test Codes

CPT CODE 85730, 85240, 85384, 85576x11, 85610, 85245, 85246, 85670
LOINC CODE 14979-9, 3209-4, 3255-7, 48805-6, 5902-2, 6301-6, 6014-5, 3243-3