Free Dihydrotestosterone (DHT), Serum Test
The free DHT test measures the concentration of free dihydrotestosterone in a serum sample, the portion not bound to sex hormone binding globulin (SHBG). Quest describes DHT as the most potent androgen, involved in male external genitalia development, prostate growth and skin metabolism.
About this test
Dihydrotestosterone, or DHT, is an androgen hormone. This test measures the free fraction, the portion of DHT in serum that is not bound to sex hormone binding globulin (SHBG).
The sample is collected in a red-top tube and analyzed using equilibrium dialysis combined with chromatography/mass spectrometry. Quest notes that results are interpreted alongside clinical and family history and physical examination findings, not read on their own.
Who might consider this test?
- Quest describes this test as useful in evaluating 5-alpha-reductase deficiency
- A condition affecting male sexual development
- In evaluating therapies that affect androgen levels
Test details
| Quest code | 36168 |
|---|---|
| Methodology | Equilibrium Dialysis • Chromatography/Mass Spectrometry |
| Sample type | 1.5 mL serum |
| Collection | Quest patient service center |
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Additional details
What this test looks at
The test reports the concentration of free dihydrotestosterone in serum, using equilibrium dialysis and chromatography/mass spectrometry. Quest also lists it under the alias male hormone low t.
How it's often used alongside other tests
Quest describes an elevated ratio of testosterone to DHT as something that may support evaluation for 5-alpha-reductase deficiency, though it notes that a definitive diagnosis requires DNA analysis of the SRD5A2 gene. Results are read alongside clinical and family history and physical examination findings, not in isolation.
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 the free DHT test measure?
It measures the concentration of free dihydrotestosterone in serum, the portion not bound to sex hormone binding globulin, using equilibrium dialysis and chromatography/mass spectrometry.
How is the sample collected?
The test uses a serum sample collected in a red-top tube 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.
What is free DHT used to evaluate?
Quest describes it as useful in evaluating 5-alpha-reductase deficiency, a condition affecting male sexual development, and in evaluating therapies that affect androgen levels.
Can this test diagnose 5-alpha-reductase deficiency on its own?
No. Quest notes that a definitive diagnosis requires DNA analysis of the SRD5A2 gene; this test's result is read alongside clinical and family history and physical examination findings.
How much is a DHT Free & Total test?
$260, paid once at checkout. The price includes the physician's order this test requires and sample collection at a Quest patient service center.