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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. DO NOT collect any specimens before 0800 or after 1600.

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 11/29/2017 3:47:45 PM
Entry Number 1713
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