Testosterone, Free, Direct With Total Testosterone

State patient’s age and sex on the test request form.

This panel includes Testosterone, Total, which 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.

Expected Turnaround Time

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Specimen Requirements

Specimen

Volume

Minimum Volume

0.7 mL (Note: This volume does not allow for repeat testing.)

Container

Collection

If a red-top tube is used, transfer separated serum to a plastic transport tube.

Storage Instructions

Stability Requirements

Causes for Rejection

Gross lipemia (may yield erroneously high free testosterone results); plasma specimen

Test Details

Use

Evaluate hirsutism and masculinization in women; evaluate testicular function in clinical states where the testosterone binding proteins may be altered (obesity, cirrhosis, thyroid disorders). See individual test descriptions for more information.

Limitations

A pediatric reference interval has not been established for the direct free testosterone test.

Methodology

Free: Direct analog enzyme immunoassay (EIA); Total: electrochemiluminescence immunoassay (ECLIA)

LOINC® Map

Order Code	Order Code Name	Order Loinc	Result Code	Result Code Name	UofM	Result LOINC
140103	Testosterone,Free and Total	58952-3	004227	Testosterone	ng/dL	2986-8
140103	Testosterone,Free and Total	58952-3	144981	Free Testosterone(Direct)	pg/mL	2991-8

For Providers

The LOINC® codes are copyright © 1994-2021, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf

Testosterone panel