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Test Code K Potassium Level

Clinical System Name

Potassium Level


Measurement of serum potassium is used for evaluation of electrolyte imbalance, cardiac arrythmias, muscular weakness, hepatic encephalopathy, and renal failure, and for monitoring of ketoacidosis in diabetes mellitus and intravenous fluid replacement therapy. Low potassium is common in hypertensive patients with aldosteronism, vomiting, diarrhea, alcoholism, and folic acid deficiency. High potassium values occur in rapid potassium infusion, end stage renal failure, hemolysis, trauma, Addison’s disease, metabolic acidosis, acute starvation, dehydration, and acute medical emergencies.

Sample Requirements

Specimen: Whole Blood

Container(s):  Gold SST, Dark Green/Sodium Heparin, Red, Gold Microtainer, Lt. Green/Li Heparin Microtainer, or Heparinized Syringe

Preferred Vol:  1.0 mL

Minimum Vol:  0.5 mL


Notes: Avoid hemolysis and contamination from IV line or tissue fluids. Method is affected by moderate to marked lipemia, slight - moderate hemolysis (increases K by 0.3 mMol/L), tissue fluid from difficult fingerstick, line dilution or contamination. Not affected by lithium, NH3 or sodium heparin. Red, and Gold SST tubes are acceptable, but not preferred. Warming hand or foot prior to drawing capillary sample is recommended. Potassium is leaked from cells on standing.


Processing Instructions

Reject due to:  Age of Specimen

Spin: Y

Aliquot: Y

Temp:  2-8oC

Storage location:  Core 5 Chemistry Refrigerator


Off-site collection: Avoid hemolysis and contamination from IV line or tissue fluids. Spin blood, aliqout serum or plasma and refrigerate at 2-8oC . Potassium is leaked from cells on standing.



Specimen Type Temperature Time
Serum or Plasma RT

6 W

Serum or Plasma 2-8oC

 6 W

Serum or Plasma -20oC or -70oC

 365 D



STAT Performed TAT
Y 24/7 1 H


Performing Laboratory

Seattle Children's Laboratory    


Department:  Core Chemistry

Phone Number: 206-987-2617



Reference Range

Age mEq/L
0-2 D 3.7 - 5.9
2 D - 3 M 3.4 - 5.6
> 3 M 3.5 - 5.5



Method:  Potentiometric method by Vitros 4600

Analytical Volume:  0.05 mL serum or plasma (Vitros 4600)


CPT Codes


Critical Values


Age mEq/L
0-2 D

< 3.1 mEq/L  or ≥ 6.4 mEq/L

2 D - 3 M

< 3.1 mEq/L  or > 5.9 mEq/L

> 3 M

< 3.1 mEq/L  or > 5.9 mEq/L