Rev. Date: 12-Jul-11 Art: 714174-00J
POTASSIUM/K
Potassium is measured by ion-selective electrode potentiometry. In the calculation of results for potassium,
concentration is related to potential through the Nernst equation.
The i-STAT System uses direct (undiluted) electrochemical methods. Values obtained by direct methods may
differ from those obtained by indirect (diluted) methods.
1
See below for information on factors affecting results. Certain substances, such as drugs, may affect analyte
levels in vivo.
2
If results appear inconsistent with the clinical assessment, the patient sample should be retested using
another cartridge.
Intended Use
The test for potassium, as part of the i-STAT System, is intended for use in the in vitro quantification of
potassium in arterial, venous, or capillary whole blood.
Potassium measurements are used in the diagnosis and monitoring of diseases and clinical conditions that
manifest high and low potassium levels.
Contents
Each i-STAT cartridge contains one reference electrode (when potentiometric sensors are included in the
cartridge configuration), sensors for the measurement of specific analytes and a buffered aqueous calibrant
solution that contains known concentrations of analytes and preservatives. For cartridges that contain a
sensor for the measurement of potassium, a list of reactive ingredients is indicated below:
Reactive Ingredient
Potassium (K
+
)
Metrological Traceability
The i-STAT System test for potassium measures potassium amount-of-substance concentration in the
plasma fraction of arterial, venous, or capillary whole blood (dimension mmol L
-1
) for in vitro diagnostic use.
Potassium values assigned to i-STAT’s controls and calibration verification materials are traceable to the
U.S. National Institute of Standards and Technology (NIST) standard reference material SRM956. i-STAT
System controls and calibration verification materials are validated for use only with the i-STAT System and
assigned values may not be commutable with other methods. Further information regarding metrological
traceability is available from Abbott Point of Care Inc..
Expected Values
Reportable Reference
Test/Abbreviation Units* Range Range
3
Potassium/K mmol/L(mEq/L) 2 – 9 3.5 – 4.9**
*The i-STAT System can be configured with the preferred units.
**The reference range for potassium listed above has been reduced by 0.2 mmol/L from the range cited in Reference 3 to account for the difference
between serum and plasma results.
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