Specimen Requirements

Container/Tube:

Preferred:  Mint Green-top (lithium heparin) tube-Hemolyzed specimen or sodium heparin tube is not acceptable.

Acceptable:  Green-top tube, gold-top serum gel tube or plain, red-top tube

Specimen: 0.2 mL of lithium heparin plasma or serum

Stability: 3 days at 4°C

Collection Instructions: For glucose testing a fasting specimen is preferred. Tube should be kept capped as much as possible to avoid decreasing the CO2 concentration.  Immediate testing is preferred.

Note: Elevated platelets can cause a falsely elevated serum potassium level because of the release of potassium during clotting process. Specimens from patients with elevated platelet counts must be drawn in a heparinized plasma tube.