Specimen must remain unopened-cannot be exposed to air
Container/Tube: (Preferred) PST
Alternate specimen: whole blood drawn in a lithium heparin vacutainer tube is acceptable
Specimen Volume: 5 mL of heparinized whole blood
Collection/Stability:
- Plasma – Collect the sample in a green lithium heparin plasma separator tube, spin within 30 minutes of collection and refrigerate for up to 72 hours. Do not expose the plasma to air.
- Whole blood-samples should be analyzed as soon as possible (within 30 minutes of collection). If immediate analysis is not possible, the sealed blood samples must be placed in a bath containing ice and water to slow down the metabolic process. Ice-water stored samples at 1 to 4°C (33.8 to 39.2°F) may give reliable ionized calcium results for up to 12 hours.