Testosterone Free and Total (Minors <18y) (Sendout)

Useful For: Alternative, second-level test for suspected increases or decreases in physiologically active testosterone:

• Assessment of androgen status in cases with suspected or known sex hormone-binding globulin-binding abnormalities
• Assessment of functional circulating testosterone in early pubertal boys
• Assessment of functional circulating testosterone in women with symptoms or signs of hyperandrogenism, but normal total testosterone levels

Ordering Note: For patients =>18 years old, order Testosterone, Total and Free (Patients => 18 yrs) [FTTEST].

Free Testosterone: Equilibrium Dialysis/Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Total Testosterone: Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Cautions:

Early-morning testosterone levels in young male individuals are, on average, 50% higher than p.m. levels. Reference values were established using specimens collected in the morning.

Testosterone levels can fluctuate substantially between different days, and sometimes even more rapidly. Assessment of androgen status should be based on more than a single measurement.

The low end of the normal reference range for total testosterone in prepubertal subjects is not yet established.

While free testosterone can be used for the same indications as bioavailable testosterone, determination of bioavailable testosterone levels may be superior to free testosterone measurement in most situations.

6 mL blood in a RED TOP Tube

Unacceptable: Serum gel/SST tubes

Outside Laboratories: Centrifuge sample and transfer serum to a separate plastic vial. Refrigerate serum while awaiting shipment. Transport with a cold pack.

Stability: Refrigerated (preferred): 14 days; Frozen: 60 days; Ambient: Unacceptable.

Centrifuge sample and transfer serum to a separate plastic vial. Refrigerate serum.

Sendouts:

• Order Mayo Test: TGRP
• Interfaced: Yes [Interface: 601; Worksheet: MARF]
• Note: Do not send research samples (RTS), regardless of age.

Stability: Refrigerated (preferred): 14 days; Frozen: 60 days; Ambient: Unacceptable.