Platelet Function ASA (Verify Now)

Abbrev Code:ASA   
Order Code:LAB5337Order Name:Platelet Function ASA
Synonyms:Aspirin; VerifyNow ASA; Platelet Function ASA; Platelet Function Aspirin
Methodology:Turbidmetric-based optical detection
CPT Codes: 85576 x1
Turnaround Time:Performed and reported 24 hours/day.
Special Instructions:
This test requires a special tube be used that can only be filled to one amount for proper testing results. Test must be performed within 4 hours of collection. Specimen must be hand delivered; do not send via Pneumatic Tube System (PTS). This test is intended for patients on anti-platelet medication and is not intended for patients with genetic abnormalities.

Patients who have been treated with glycoprotein IIb/IIIa inhibitors should not be tested until the platelet function has recovered. This time period is approximately 48 hours after discontinuation of eptifibatide and tirofiban, and 14 days after discontinuation of abciximab. Other platelet drugs such as P2Y12 inhibitors (e.g. clopidogrel), NSAIDs, etc. may also affect the results of this assay.  

Collection Instructions

Optimal Volume:Two 2 mL Greiner tubes.
Minimum\Peds Volume:One 2 mL Greiner tube.
Container:9 NC Coagulation Sodium Citrate (Greiner tube)
Collection Instructions:
  • Peripheral Samples: Blood samples should be obtained from an extremity free of peripheral venous infusions. Whole blood samples must be collected using a 21 or larger gauge needle. Collect a discard sample of at least 2 mL in a tube containing sodium citrate or no additive.  Gently invert the sample tubes at least 5 times to ensure complete mixing of the contents.
  • Indwelling Venous Catheters: Collect a discard sample of at least 5 mL in a tube containing sodium citrate or no additive. Transfer blood to the blood collection tubes immediately after collection. Gently invert the sample tubes at least 5 times to ensure complete mixing of the contents.

Only one test may be assayed per tube. If ordering both ASA and P2Y12, additional specimens are required.
NOTE: If drawing an EDTA tube at the same time as sample collection for VerifyNow Aspirin test, fill the EDTA tube last.
Causes for Rejection:Specimen that is clotted, hemolyzed, underfilled, overfilled, centrifuged, not tested within 4 hours of collection, sent via PTS, or stored in the refrigerator or freezer prior to testing.

Processing and Shipping

Specimen Processing:Whole blood. Do not process.
Shipping Instructions:Hand-deliver. Must arrive for testing within 4 hours of collection at room temperature.
Test Performed at or Referral Lab Coagulation  (Southdale, UMMC East Bank, UMMC/UMMCH-West Bank)


Reference Range:
Aspirin Assay Result
Therapeutic range Less than 550 ARU
Non-therapeutic range
(less inhibition by aspirin
Greater than or equal to 550 ARU
Test results are reported in Aspirin Reaction Units (ARU), which indicate the amount of thromboxane A2-mediated activation of glycoprotein IIb/IIIa receptors involved in platelet aggregation. ARU is calculated as a function of the rate and extent of platelet aggregation. The lower the value, the more inhibition is present, consistent with a response to aspirin.

Test performance is affected by hematocrits less than 29% or greater the 56%, and platelet counts less than 92 x 109/L.
Therapeutic Range:Therapeutic Range (for aspirin): Less than 550 ARU
Use:Aids in the detection of platelet inhibition due to aspirin therapy.

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