14 days
Equilibrium dialysis and high-pressure liquid chromatography (HPLC) with tandem mass spectrometry.
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Highly aurate measurement of free cortisol. Used in adrenal and Cushing assessments.
Serum
1.6 mL
Red-top tube or gel-barrier tube
No special preparation is required for this test. You may eat, drink, and take your medications as normal, unless instructed otherwise by your healthcare provider.
Strictly frozen, requires own sample container
| Temperature | Period |
|---|---|
| Room temperature | 7 days |
| Refrigerated | 7 days |
| Frozen | 6 months |
| Freeze/thaw cycles | stable x6 |