Gold serum separator (SST) tube
Immediately following collection, mix sample by gently inverting 5 times
Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp)
Red serum vial/tube - 5 mL
Frozen (preferred) – 1 year
Refrigerated – 1 day
Ambient – 1 day
HPLC/tandem mass spectrometry
Radioimmunoassay (RIA)
Calculation of free cortisol