Cortisol, Free and Total, LC/MS Test
This test measures both free and total cortisol concentrations in a blood serum sample. Quest describes free cortisol measurement as used in evaluating Cushing's syndrome, a condition in which free cortisol is elevated.
About this test
The test analyzes a serum sample, collected in a red-top tube without gel, using equilibrium dialysis combined with chromatography/mass spectrometry (LC/MS). This method reports both the total cortisol concentration and the free, unbound portion.
Quest describes elevated free cortisol concentrations as associated with Cushing's syndrome, and notes that free cortisol measurement is used in evaluating that condition. Reporting free cortisol alongside the total gives a clinician a more complete read than the total value alone.
Test details
| Collection | Quest patient service center |
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Quest resources
Additional details
What this test looks at
The test reports two values from the same sample: total cortisol and free cortisol, both measured by equilibrium dialysis combined with chromatography/mass spectrometry on a 2 mL serum sample. The LC/MS methodology is a chromatography and mass spectrometry technique that separates and identifies cortisol precisely within the sample.
This test isn't part of the Celio Health store at the moment, so it can't be ordered or requested here. The test menu lists everything that can.
Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.
Frequently asked questions
What does this test measure?
It measures both total and free cortisol concentrations in a serum sample, using equilibrium dialysis combined with chromatography/mass spectrometry.
How is the sample collected?
The test uses a 2 mL serum sample, collected in a red-top tube without gel.
Do I need to prepare for this test?
No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.
Why measure free cortisol separately from total cortisol?
Quest describes free cortisol measurement as used in evaluating Cushing's syndrome, a condition in which free cortisol concentrations are elevated, distinct from the total cortisol value.