PT/INR - 6 Art: 715236-00N Rev. Date: 01-Mar-12
Factors Affecting Results
• The presence of exogenously added heparin, citrate, oxalate, or EDTA from blood collection devices
will interfere with test results.
• Poor technique in sample collection may compromise the results. (See Specimen Collection and
Preparation below.)
• Glass syringes or tubes may prematurely activate coagulation, resulting in accelerated clotting times
and lower INRs. Venous samples must be collected into plastic syringes or tubes.
• PT/INR results may be affected by commonly administered drugs.
• Abbott Point of Carehas not characterized the i-STAT PT/INR test with patients that have lupus
anticoagulant antibodies. If the presence of lupus anticoagulant antibodies is known or suspected,
consider using a prothrombin time laboratory assay using a reagent that is known to be insensitive
to lupus anticoagulant antibodies or an alternate laboratory method.
Limitations of the i-STAT PT/INR Test
• The analyzer must remain on a level, vibration free surface with the display facing up during testing.
A level surface includes running the handheld in the downloader/recharger.
• The i-STAT PT/INR test is not affected by fibrinogen concentrations between 70 and 541 mg/dL.
• The i-STAT PT/INR test is not affected by unfractionated heparin concentrations up to 1.0 U/mL.
• Hematocrits in the range of 24 – 54% PCV have been demonstrated not to affect results.
• Cubicin
®
(daptomycin for injection) has been found to cause a concentration-dependent false
prolongation of prothrombin time (PT) and elevation of INR when using the i-STAT PT/INR test. It
is recommended that for patients being treated with this antibiotic, an alternate method be used to
evaluate PT/INR.
• The i-STAT PT/INR test may report a false prolongation of the prothrombin time (PT) and an
elevation of the INR on samples contaminated with Chlorhexidine Gluconate.
• Thei-STATPT/INRtestisnotintendedforevaluatingindividualfactordeficiencies.
Specimen Collection and Preparation
Caution: The i-STAT PT/INR cartridge is designed to accept a sample between 20 and 45 microliters.
A single drop of blood from either a finger puncture or as formed at the tip of a syringe will
typically be within this range. If a larger volume is delivered to the sample well, use caution
when closing the cartridge as excess blood may be expelled from the cartridge.
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