iCa - 4 Art: 714179-00L Rev. Date: 01-Aug-11
The following substances are known not to significantly interfere with the i-STAT Ionized Calcium
assay at the stated test concentrations:
Substance
Test Concentration
(mmol/L)
Acetaminophen (therapeutic) 0.132
Acetylcysteine (therapeutic) 0.30
8,9
Ascorbate 0.34
Bromide (therapeutic) 2.5
11,12,13
β- Hydroxybuterate 6.0
14
Notes:
1) Acetaminophen has been shown to interfere at a concentration proscribed by the CLSI guideline, 1.32
mmol/L, which represents a toxic concentration. Acetaminophen at 0.132 mmol/L, which represents the
upper end of the therapeutic concentration, has been shown not to significantly interfere with i-STAT ion-
ized calcium results.
2) Acetylcysteine has been tested at two levels; the CLSI recommended level and a concentration of
0.30 mmol/L. The latter is 3 times the peak plasma therapeutic concentration associated with treatment
to reverse acetaminophen poisoning. APOC has not identified a therapeutic condition that would lead
to levels consistent with the CLSI recommended level. Acetylcysteine at a concentration of 10.2 mmol/L
decreased i-STAT ionized calcium results, while acetylcysteine at a concentration of 0.3 mmol/L did not
significantly interfere with ionized calcium results.
3) Bromide has been tested at two levels; the CLSI recommended level and a therapeutic plasma con-
centration level of 2.5 mmol/L. The latter is the peak plasma concentration associated with halothane
anesthesia, in which bromide is released. APOC has not identified a therapeutic condition that would
lead to levels consistent with the CLSI recommended level. Bromide at a concentration of 37.5 mmol/L
increased i-STAT ionized calcium results, while bromide at a concentration of 2.5 mmol/L did not signifi-
cantly interfere with i-STAT ionized calcium results.
4) Salicylate has been shown to significantly decrease ionized calcium results at a concentration pro-
scribed by the CLSI guideline, 4.34 mmol/L, which represents a toxic concentration.Salicylate at 0.5
mmol/L, which represents the upper end of the therapeutic concentration, has been shown to decrease
ionized calcium results by approximately 0.03 mmol/L.
*It is possible that other interfering substances may be encountered. The degree of interference at concentrations other than those listed might not
be predictable.
To Next Page
Loading...
