Testosterone, Free (Dialysis) and Total, MS Test
This test measures both free and total testosterone from one blood sample, using chromatography/mass spectrometry and equilibrium dialysis. Quest describes it as used in assessing testicular function and certain hormone-related conditions.
About this test
Testosterone circulates in the blood both bound to carrier proteins and in a small free fraction available to tissues. This test reports total testosterone, measured by chromatography/mass spectrometry, and free testosterone, calculated from an equilibrium dialysis measurement, from the same 1.
Quest describes the paired result as used in assessing testicular function in prepubescent hypogonadal males and in managing hirsutism and virilization in females. Because the test reports both the total hormone level and the portion that is free and biologically available, a clinician can look at each figure in the context of the clinical question being asked.
Who might consider this test?
- People who talk with their clinician about this test are typically working through a specific hormone-related question
- Because the test reports two related values rather than one, the reason for ordering shapes which figure the clinician weighs more heavily.
Test details
| Quest code | 36170 |
|---|---|
| Methodology | Chromatography/Mass Spectrometry • Equilibrium Dialysis • Calculation |
| Sample type | 1.8 mL serum |
| Collection | Quest patient service center |
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Quest resources
Additional details
What this test looks at
The test reports two testosterone values from one serum sample: total testosterone, measured by chromatography/mass spectrometry, and free testosterone, determined using equilibrium dialysis with a calculation. Quest lists this combination under several names, including Free & Total Testosterone LC/MS/MS, Testosterone Index and Free and Unbound Testosterone.
How it's often used alongside other tests
Quest describes this paired testosterone measurement as used in assessing testicular function in prepubescent hypogonadal males and in managing hirsutism and virilization in females. A clinician reads the total and free values together with the clinical picture that prompted the test, rather than looking at either number alone.
Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.
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 testosterone from one serum sample. Total testosterone is measured by chromatography/mass spectrometry, and free testosterone is determined using equilibrium dialysis with a calculation.
How is the sample collected?
The test uses a 1.8 mL serum sample from a routine blood draw at a Quest Diagnostics patient service center.
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.
Who is this test used for?
Quest describes it as used in assessing testicular function in prepubescent hypogonadal males and in managing hirsutism and virilization in females.
What is the difference between free and total testosterone here?
Total testosterone reflects the hormone bound to carrier proteins plus the free fraction; free testosterone is the portion not bound to protein. This test reports both from the same sample.
Can I get the Testosterone, Free and Total, MS test without a doctor's visit or insurance?
Yes. The $185 cash price includes an independent physician's order, so no referral is needed, and insurance is never involved.