What is this test?
The test evaluates the free, unbound portion of testosterone that is more accessible to the tissues.
Why might it be ordered?
- With symptoms of androgen deficiency or excess, when total testosterone does not provide sufficient information.
- For evaluation of changes in SHBG, menstrual disorders, infertility or sexual symptoms.
What sample is needed?
A healthcare professional collects a venous blood sample. Depending on the method, the laboratory uses serum or plasma.
How should you prepare?
Collection time matters, especially in men. Follow instructions for a morning sample and report any hormone treatment. Tell the laboratory about all medicines, hormone treatments, vitamins and supplements you take. Do not stop or change treatment unless your clinician tells you to. Follow any instructions about fasting and the time of collection.
How should you understand the result?
The result depends on the method and is interpreted with total testosterone and SHBG. Do not directly compare values from different methods. Your result is interpreted using the reference interval on the laboratory report and in the context of your symptoms, medical history and other test findings.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.