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Potassium, Serum / Plasma

Item Value
Approval req'd? No
Available Stat? Yes
Test code K
Test group Potassium
Performed by Parnassus & Mt. Zion Chemistry
In House Availability Test available 24 hours per day 7 days per week
Method Ion Specific Electrode (ISE)
Container type Gold top or Light Green top
Amount to Collect 1 mL blood Click here for Microdetermination info
Sample type Serum, Heparinized plasma
Preferred volume 0.5 mL serum or plasma
Min. Volume 0.2 mL serum or plasma Click here for Microdetermination info
Units mmol/L
Normal range
< 1 year 3.2-6.0 mmol/L
> 1 year 3.8-5.1 mmol/L


1. Normal range for infants 0 to <1 year adopted from Soldin, Steven J., "Pediatric Reference Intervals", 6th edition, AACC Press, 2007, method 4.
2. Adult range used for children >1 year old.
3. Normal range for adults was determined by testing 271 male and female healthy blood donors at UCSF.
Critical value < 3.0 mmol/L or > 6.0 mmol/L
Synonyms K; K+; Electrolytes
Stability Room temperature 8 hours, refrigerated 2 days, frozen at -20C 1 week
Turn around times STAT 1 hour, Routine 4 hours
Additional information Hemolysis may artifactually increase the result. Levels in serum are normally 0.3 mmol/L higher than plasma levels due to liberation of potassium by platelets during clotting (c. 0.07 mmol/L per 100K platelets). Thus not only hemolysis but thrombocytosis can falsely elevate potassium levels, which can be circumvented by measuring plasma rather than serum potassium. Values < 1.5 or > 12 are automatically reassayed.
LOINC code 2823-3
Last Updated 10/15/2014 11:47:09 AM
Entry Number 766
Lab Procedure Link Click here for Procedure
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