Test Details
Free Testosterone
Free testosterone is a measurement of testosterone that is not bound to SHBG. Testosterone is the most potent naturally occurring androgen and is produced by the interstitial cells of the testes in response to stimulation by luteinizing hormone (LH). Testosterone is also produced by the ovary and adrenal cortex in small amounts and is responsible for the regulation of gonadotropic secretion and spermatogenesis as well as the development of secondary sex characteristics.
Methodology
Calculation
Patient Preparation
None
Preferred Specimen
1.0 mL serum (0.5 mL minimum) collected in serum separator tube (SST / Tiger Top)
Alternate Specimen
Dried Blood collected on an AdvanceDx 100 card (Men Only)
Transport Temperature
Refrigerated (ship on frozen cold packs)
Stability
Refrigerated: 5 days
Lab Values
Free Testosterone
Female
| Age | Optimal |
| <20 yrs | Not Established |
| ≥20 yrs | 1.1 – 9.7 pg/mL |
Male
| Age | Optimal |
| <20 yrs | Not Established |
| ≥20 yrs | 57.3 – 240.0 pg/mL |
Clinical Significance
Free Testosterone
Testosterone is used in the diagnosis and treatment of the following disorders:1-4
- Primary and secondary hypogonadism
- Delayed or precocious puberty
- Impotence in males
- Hirsutism (excessive hair) and virilization (masculinization) in females due to polycystic ovaries, tumors and adrenogenital syndromes
References:
- Bhasin S, Cunningham GR, Hayes FJ, et al. Testosterone therapy in men with androgen deficiency syndromes: Endocrine Society clinical practice guidelines. J Clin Endorcinol Metab. 2010;95(6):2536-2559.
- Santen RJ, Allred DC, Ardoin SP, et al. Postmenopausal hormone therapy: an Endocrine Society scientific statement. J Clin Endocrinol Metab. 2010;95(7 Suppl 1):s1-s66.
- Kopper NW, Gudeman J, Thompson DJ. Transdermal hormone therapy in postmenopausal women: a review of the metabolic eff ects and drug delivery technologies. Drug Des Devel Ther. 2008;2:193-202.
- Goodman N, Cobin RH. Reproductive disorders. In: Camacho PM, Gharib H, Sizemore GW, eds. Evidence-Based Endocrinology. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins. 2012:190-228.
Treatment Options
Free Testosterone
- Identify etiology of elevated or decreased free testosterone levels with physical assessment and additional diagnostic tests as indicated
- Treatment is based on etiology of abnormal hormone level
