TEST DIRECTORY | MIDx Labs

TESTOSTERONE, FREE (FTST)

Reflects the biologically active, unbound fraction of testosterone.

LIS TEST CODE: FTESTO

CPT CODE: 84270 (SHBG) + 84403 (TESTO)

ALIASES: FTESTO, TGRP

METHODOLOGY: Calculation (Vermeulen Equation)

SPECIMEN:

- Type: Serum

- Container: Gold Top (SST) Vacutainer

- Minimum Volume Required: 1 mL

- Storage/Handling: Allow 30 minutes for blood to clot, then centrifuge specimen at 3500 RPM for 10 minutes. Maintain specimen in the refrigerator until testing can be performed.

- Stability: Room Temperature (20-25 °C): Not Accepted

Refrigerated (2-8 °C): 7 days

Frozen (-20 °C or colder): Not Accepted

- Turnaround Time: 24 hours from receipt.

Special Instructions: Remove serum from separator gel and transfer into a plastic screw-cap aliquot tube as soon as possible after complete clot formation.

REJECTION REASONS: QNS, Gross Hemolysis, Gross Lipemia, Contamination, Stability Violation, Expired Container, Incorrect Container

REFERENCE RANGES:

Males & Females (pg/mL)

>= 1 years of age: See Comment

Sex/Age Free Testosterone (pg/mL)
Male, 18 - 69 years old: 46.0 - 224.0
Male, > 69 years old: 6.0 - 7.3
Female, 18 - 69 years old: 0.2 - 5.0
Female, > 69 years old: 0.3 - 5.0

Free Testosterone is calculated using Total Testosterone (ng/dL) and SHBG (nmol/L), with Albumin assumed at 4.3 g/dL (Vermeulen Equation). This calculation method may not be suitable for patients with substantially altered protein status. Reference intervals are method-dependent and should be interpreted in conjunction with clinical findings.