Testosterone Free, Profile I

Casandra

Casandra Test Code LC35703Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 140226CPT Codes 82040, 84270, 84403

Testosterone Free, Profile I

Also known as: Free Testosterone by Vermeulen Equation, Free Testosterone, Calculated

Clinical Use

Order Test

Use

Free testosterone is the concentration of unbound testosterone in serum.1 The majority (approximately 60% to 90%) of serum total testosterone is associated with sex hormone binding globulin (SHBG); this fraction is tightly bound and biologically unavailable to its target tissues. The remaining bioavailable testosterone is mostly bound to albumin, with only a small fraction (approximately 0.5% to 2%) circulating in the free form.1,2 Free testosterone is the form of testosterone that can diffuse into the tissues and act on receptors and is considered the active fraction by many physicians.1,3,4 Free testosterone assessment is recommended as a primary or secondary measure of androgen activity in men2,5-11 and women.12-16 The equilibrium dialysis or ultrafiltration methods are recommended, however they are relatively difficult and expensive to perform. All of these methods are currently available from LabCorp.

Special Instructions

This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.