Testosterone, Free and Total, Includes Sex Hormone-Binding Globulin (Adult Males or Individuals on Testosterone Hormone Therapy)
Also known as: FREE T
Use
This test provides a calculated value for free testosterone concentration using total testosterone measured by immunoassay. It is used to evaluate hypogonadism in cisgender males with a total testosterone concentration at the lower limit of normal and may be used to evaluate testosterone status in individuals with protein-binding abnormalities or to monitor testosterone hormone therapies. It is not recommended for instances where low testosterone concentrations are expected, such as in children and cisgender females; in these cases, testing by mass spectrometry is recommended.
Special Instructions
Collect specimens between 6-10 a.m. using a serum separator tube or green (lithium heparin) tube. Allow serum specimens to clot completely at room temperature and separate serum or plasma from cells as soon as possible or within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube, with a minimum of 0.6 mL required.
Limitations
Testosterone immunoassays are both imprecise and inaccurate at low testosterone concentrations, such as those found in children and cisgender females. For these individuals, testing by mass spectrometry is recommended to ensure accurate results. The concentration of free testosterone is calculated based on the binding constant of testosterone to sex hormone-binding globulin, and the reference intervals are not established for males younger than 14 years or cisgender females.
New York Approved
Methodology
Immunoassay (ECLIA)
Biomarkers
LOINC Codes
- 13967-5
- 15432-8
- 2986-8
- 2991-8
- 2991-8
- 15432-8
- 2986-8
- 13967-5
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.6 mL
Container
Serum separator tube or green (lithium heparin)
Collection Instructions
Allow serum to clot completely at room temperature. Separate serum or plasma from cells ASAP or within 2 hours of collection. Transfer to an ARUP Standard Transport Tube.
Patient Preparation
Collect specimen between 6-10 a.m.
Storage Instructions
Refrigerated
Causes for Rejection
EDTA plasma
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |
| Refrigerated | 1 week |
| Frozen | 2 months |
Other tests from different labs that may be relevant