Testosterone Free and Total (Minors <18y)

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General Information

Lab Name
Testosterone, Free and Total (Minors <18y)
Lab Code
RTESFT
Epic Name
Testosterone Free and Total (< 18 yo only) (Sendout)
External Test Id
TGRP
Description

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].

Synonyms
TGRP
Components
Code Name
RTTEST Testosterone
RTSTF Testosterone, Free

Interpretation

Method
  • Testosterone, Free: Equilibrium Dialysis/Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
  • Testosterone, Total: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Reference Range
See individual components
Interferences and Limitations

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.

Ordering & Collection

Specimen Type
Blood
Collection

8 mL blood in a RED TOP Tube

  • Unacceptable: GOLD SST Tube
Handling Instructions

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

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

Reject Due To: Gross hemolysis, lipemia, or icterus.

Quantity
Requested: 2.5 mL serum
Minimum: 1 mL serum

Processing

Receiving Instructions

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.

Reject Due To: Gross hemolysis, lipemia, or icterus.

Misc Sendout

Performance

Lab Department
Sendouts Mayo Lab (RF)(MARF)
Frequency
Performed: Monday through Saturday. Report Available: 3-8 days from sample receipt at Mayo Clinic Laboratories.
Available STAT?
No
Performing Location(s)
Sendout Mayo Clinic Laboratories (Superior Drive)
800-533-1710

3050 Superior Drive NW
Rochester, MN 55901

Billing & Coding

CPT Codes
84402, 84403
LOINC
58952-3
Interfaced Order Code
UOW1709