Testosterone, free and total, by equilibrium ultrafiltration mass spectrometry
Test Mnemonic
TFTEST
CPT Codes
- 84402 - QTY (1)
- 84403 - QTY (1)
Includes
- Testosterone, % Free, S
- Testosterone, Free, S
- Testosterone, Total, S
Performing Laboratory
LabCorp
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 2.2 mL | Serum | No additive (Red) | Ambient | Separate serum from cells within 1 hour and transfer to standard aliquot tube. |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1.8 mL | Note: This volume does not allow for repeat testing. |
Stability
| Environmental Condition | Description |
|---|---|
| Refrigerated | 7 days |
| Frozen | 5.58 years (9 freeze/thaw cycles) |
| Ambient | 7 days |
Days Performed
Varies
Turnaround Time
5 - 7 days
Methodology
| Name | Description |
|---|---|
| High Performance Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS) | |
| Equilibrium Ultrafiltration |
Reference Range
Special Info
NOTE: Patient's age and sex are required. Hemolyzed, icteric or grossly lipemic specimens will be rejected. Specimens from patients with recently administered isotopes will be rejected. This test is New York DOH approved.
Clinical Info
This test is useful to evaluate hirsutism and masculinization in women, or to evaluate testicular function in clinical states in which the testosterone-binding proteins may be altered (obesity, cirrhosis, thyroid disorders). The concentration of free testosterone is very low, typically <2% of the total testosterone concentration. In most men and women, >50% of total circulating testosterone is bound to sex hormone-binding globulin (SHBG) and most of the rest is bound to albumin. Routinely available assay methods used to measure total testosterone are not sensitive enough to quantitate accurately the free testosterone fraction directly. Free testosterone is estimated in this profile by an indirect method, equilibrium ultrafiltration.