Cortisol, Free, Equilibrium Dialysis and LC/MS-MS
Use
Cortisol is the primary glucocorticoid in humans, affecting glucose control, inflammation, and response to stress.
Special Instructions
The test provides a direct measurement of free cortisol using equilibrium dialysis and HPLC tandem mass spectrometry. This methodology is important because cortisol binding can be affected by polymorphic forms of transcortin and glycosylation. It is useful in assessing adrenal sufficiency, especially in critically ill patients, as it directly measures free cortisol levels without the interference of binding proteins.
Limitations
The results are intended for investigational purposes and should not be utilized as a standalone diagnostic procedure. They necessitate confirmation with another established diagnostic product or procedure. Most circulating cortisol is bound to proteins, with the free hormone hypothesis suggesting the unbound cortisol is clinically important. Thus, factors like protein concentration, transcortin variants, and glycosylation can affect binding and hence the measurement.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 2145-1
Result Turnaround Time
6-10 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1.6 mL
Minimum Volume
0.8 mL
Container
Red-top tube or gel-barrier tube
Collection Instructions
Separate within two hours of venipuncture. Transfer specimen to a plastic transport tube before freezing.
Storage Instructions
Freeze. Stable at room temperature or refrigerated for seven days. Stable frozen for six months. Freeze/thaw cycles stable x6.
Causes for Rejection
Hemolysis; icteric or lipemic sample
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 7 days |
| Frozen | 6 months |