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ARU Test Aspirin Reaction

Item Value
Approval req'd? No, but must contact Hematology at x3-1747 to receive collection kit. For Neurointerventional radiology only.
Available Stat? No
Test code ARU
Performed by Hematology, Parnassus
In House Availability Monday - Friday 0800 - 1600
Method VerifyNow System
Collection Instructions Contact Hematology at x3-1747 for collection kits.

1. Whole blood samples must be collected in or immediately transferred to Greiner 2.0 mL partial fill blue top tubes containing 3.2% Sodium Citrate. The tube must be filled to its intended whole blood capacity (indicated by small black line).
2. Whole blood may be collected from venous sites using a 21 gauge or larger needle in an appropriate blood collection tube.
3. Blood samples should be obtained from an extremity free of peripheral venous infusions.
4. Collect a discard tube first (approximately 2 mL), Greiner partial fill blue tops 2nd, and a lavender for CBC last.
5. Gently invert the sample tube at least 5 times to ensure complete mixing of the contents.
6. Blood must set a minimum of 10 minutes after collection before testing but no longer than 4 hours.


Samples cannot be pneumatic tubed.

An ARU will be ordered in computer. If no CBC or CBCD is requested, Central Processing will order a hematocrit (HCT) and platelet count (PLT).
Container type
1. Greiner partial fill discard
2. Greiner partial fill 3.2% Sodium citrate blue top
3. Lavender EDTA tube

Amount to Collect 8 mL
Sample type Citrated and EDTA anticoagulated whole blood
Preferred volume 8 mL
Min. Volume 6 mL
UCSF Rejection Criteria Clotted samples or if stability period exceeded.

Incorrect tube type and/or no discard tube received.

Patients with Hct's < 33% and/or Plt's < 119
Processing notes Deliver immediately to Hematology
Units ARU
Normal range 620 - 672
Synonyms Aspirin Reaction
Stability 4 hours
Turn around times 4 hours
Additional information The VerifyNow Aspirin Test is designed to measure aspirin's expected antiplatelet effect.

Plavix¨, Ticlid¨, and Effient¨ are commonly prescribed in conjunction with aspirin. While infrequent, these agents may cause a reduction of ARU in some patients.

Test performance was not affected by hematocrit values between 29-56%, platelet count values of ≥ 92,000/µL or moderate to extensive blood hemolysis induced by physical manipulation. Based on an in-house study performed on 3/29/16, correlation showed that as platelet count increased, ARU results increased.

According to manufacturer:
≥ 550 ARU - Platelet dysfunction consistent with aspirin has not been detected

< 550 ARU - Platelet dysfunction consistent with aspirin has been detected

Results should be interpreted in conjunction with other laboratory and clinical data available to the clinician.

CPT coding 85576
LOINC code 49011-0
Last Updated 4/18/2016 4:26:10 PM
Entry Number 1713
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