Rev. Date: 03-Aug-12 Art: 716675-00L CK-MB - 5
Whole Blood
Sample Concentration Diluted Concentration % Recovery
(ng/mL) (ng/mL)
A 73.24 40.73 108.7%
B 8.90 6.07 101.5%
C 47.74 26.91 109.3%
Plasma
Sample Concentration Diluted Concentration % Recovery
(ng/mL) (ng/mL)
A 73.24 — —
B 8.90 — —
C 47.74 — —
A+B — 42.17 108.9%
B+C — 30.85 102.7%
A+C — 63.95 105.7%
Test Limitations
The frequency of suppressed results is affected by atmospheric pressure. Suppressed result rates may
increase with higher elevations (decreased barometric pressure) and may become persistent if testing
is performed at more than 7500 feet above sea level. Where unavailability of results is unacceptable,
i-STAT recommends having an alternate test method available.
Samples from patients who have been exposed to animals or who have received therapeutic or
diagnostic procedures employing immunoglobulins or reagents derived from immunoglobulins may
contain antibodies, e.g. HAMA or other heterophile antibodies, which may interfere with immunoassays
and produce erroneous results.
13-19
The generation of potentially interfering antibodies in response to
bacterial infections has been reported.
13
While this product contains reagents that minimize the effect
of these interferents, and QC algorithms designed to detect their effects, the possibility of interference
causing erroneous results should be evaluated carefully in cases where there are inconsistencies in the
clinical information.
Partially clotted samples can result in elevated CK-MB readings above the reference range, as well as
quality check code errors. To prevent this from occurring, upon drawing the whole blood sample into
a heparinized collection tube, the sample should be inverted gently at least 10 times to ensure even
dissolution of the heparin anticoagulant.
Grossly hemolyzed samples can cause a decreased alkaline phosphatase activity, resulting in decreased
detection of CK-MB, increased assay backgrounds, and/or quality check codes.
Hematocrits in the range of 0-70 % PCV have been demonstrated not to affect results. Samples with
hematocrit levels above this range have demonstrated increases in the test imprecision and quality
check codes.
The analyzer must remain on a flat surface with the display facing up during testing. Motion of the
analyzer during testing can increase the frequency of suppressed results or quality check codes. A level
surface includes running the handheld in the downloader/recharger.
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