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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Platelet Aggregation, Whole Blood

Test Code(s): WBPA / HCWBPA

CPT Code(s): 85576x4, 823975x5

Methodology: Impedance/Luminescence

Clinical Significance: Test measures the ability of platelets to aggregate and/or release in whole blood in response to ADP, arachidonic acid, collagen, thrombin and ristocetin.

Days Performed: Mon-Fri, 0800-1300 - day varies. Specimens must be received in the laboratory by 1230. Testing required during off hours must be approved by a Coagulation physician. Call 263-5005 before collection.

Turnaround Time: Stat: 3 hours.
Routine: 4 hours.

Specimen Requirements

Specimen: Blood

Patient Preparation: Patient must NOT have ingested aspirin for 7 days and/or antihistamines, non-narcotic analgesics, or NSAIDs for 48 hours prior to sample collection.

Collection Instructions: Do NOT draw through a line containing heparin. The venipuncture MUST be atraumatic to avoid hemolysis and contamination with tissue factors and platelet activators. Tube must be allowed to fill completely.

Please indicate patient history and if patient is receiving anticoagulant (Warfarin/Heparin/Vitamin K antagonist), direct thrombin inhibitor or fibrinolytic agent therapy and duration on request form.

Collection Container: Preferred: Light blue top (3.2% NaCitrate)

Collection Volume: Preferred: Five full 3.5 mL tubes
Pediatrics: Six full pediatric tubes filled to fill mark.

Sample Analyzed: Whole Blood

Volume Required: Preferred: 15 mL
Pediatrics: 10 mL

Specimen Processing: Do NOT freeze, refrigerate, or centrifuge. Do NOT open tube.

Specimen Transport: Hand deliver specimen to UWHC Core Laboratory (B4/220) ASAP. Do NOT send through a pneumatic tube. Specimens must be received by UWHC laboratory by 1230 Monday through Friday.

Unacceptable Criteria: Hemolyzed or clotted specimens are not acceptable. A partially filled tube is NOT acceptable. Patient ingestion of aspirin for 7 days and/or antihistamines, non-narcotic analgesics, or NSAIDs for 48 hours prior to sample collection is not acceptable.

Stability: Ambient: 3 hours unspun
Refrigerated: Not acceptable
Frozen: Not acceptable


Reference Interval:

Normal, Increase

Test Limitations:

Platelet count must be greater than 75 K/mcL for test results to be valid.

Additional Information:

NOTE: A Platelet Function Screening test utilizing the Dade Behring PFA-100 is also available. See "Platelet Function Screen" or call (608)263-5005 for information.

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