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: 0.25 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. Bilirubin is photosensitive. Specimen must be protected from light.  Primary tubes acceptable if the test label covers the majority of the tube for transport.  If aliquoted, place in amber vial or protect from light.

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.