Provides a calculated value for free testosterone concentration using total testosterone measured by mass spectrometry. May be used to evaluate hyperandrogenism in children and cisgender females, monitor testosterone-suppressing hormone therapies (eg, antiandrogens or estrogens), evaluate testosterone status in individuals with protein-binding abnormalities, or evaluate hypogonadism in cisgender males.
To compare this test to other testosterone tests, refer to the ARUP Testosterone Tests Comparison table.
Patient Preparation
Collect between 6-10 a.m.
Collect
Serum separator tube or green (sodium or lithium heparin).
Specimen Preparation
Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP standard transport tube. (Min: 0.8 mL)
Storage/Transport Temperature
Refrigerated.
Stability (from collection to initiation)
After separation from cells: Ambient: 24 hours; Refrigerated: 1 week; Frozen: 6 months
Unacceptable Conditions
EDTA plasma.
Notes
Total testosterone and SHBG are measured and free testosterone is estimated from these measurements.
Quantitative High Performance Liquid Chromatography-Tandem Mass Spectrometry/Electrochemiluminescent Immunoassay/Calculation
Reference Interval
Components
Reference Interval
Testosterone, Free by Mass Spec
Age
Male (pg/mL)
Female (pg/mL)
1-6 years
Less than 0.6
Less than 0.6
7-9 years
0.1-0.9
0.6-1.8
10-11
0.1-6.3
0.1-3.5
12-13
0.5-98.0
0.9-6.8
14-15
3-138.0
1.2-7.5
16-17
38.0-173.0
1.2-9.9
18 years and older
47-244
Not Applicable
18-30
Not Applicable
0.8-7.4
31-40
Not Applicable
1.3-9.2
41-51
Not Applicable
1.1-5.8
Postmenopausal
Not Applicable
0.6-3.8
Tanner Stage I
Less than or equal to 3.7
Less than 2.2
Tanner Stage II
0.3-21
0.4-4.5
Tanner Stage III
1.0-98.0
1.3-7.5
Tanner Stage IV
35.0-169.0
1.1-15.5
Tanner Stage V
41.0-239.0
0.8-9.2
Interpretive Data
Free testosterone concentration is calculated using total testosterone (measured by mass spectrometry) and the binding constant of testosterone and sex hormone-binding globulin (SHBG).
For individuals on testosterone-suppressing hormone therapies (e.g., antiandrogens or estrogens), refer to cisgender female reference intervals. For a complete set of all established reference intervals, refer to ltd.aruplab.com/Tests/Pub/0081059.
Synonyms
Testosterone
Free Testosterone
0081059
CPT Codes
84402
LOINC
13967-5
49042-5
Interface Order Code (OBR)
TSTFFC
Collecting
Ordering Recommendations
Provides a calculated value for free testosterone concentration using total testosterone measured by mass spectrometry. May be used to evaluate hyperandrogenism in children and cisgender females, monitor testosterone-suppressing hormone therapies (eg, antiandrogens or estrogens), evaluate testosterone status in individuals with protein-binding abnormalities, or evaluate hypogonadism in cisgender males.
To compare this test to other testosterone tests, refer to the ARUP Testosterone Tests Comparison table.
Patient Preparation
Collect between 6-10 a.m.
Collect
Serum separator tube or green (sodium or lithium heparin).
Specimen Preparation
Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP standard transport tube. (Min: 0.8 mL)
Storage/Transport Temperature
Refrigerated.
Stability (from collection to initiation)
After separation from cells: Ambient: 24 hours; Refrigerated: 1 week; Frozen: 6 months
Unacceptable Conditions
EDTA plasma.
Notes
Total testosterone and SHBG are measured and free testosterone is estimated from these measurements.
Quantitative High Performance Liquid Chromatography-Tandem Mass Spectrometry/Electrochemiluminescent Immunoassay/Calculation
Reference Interval
Components
Reference Interval
Testosterone, Free by Mass Spec
Age
Male (pg/mL)
Female (pg/mL)
1-6 years
Less than 0.6
Less than 0.6
7-9 years
0.1-0.9
0.6-1.8
10-11
0.1-6.3
0.1-3.5
12-13
0.5-98.0
0.9-6.8
14-15
3-138.0
1.2-7.5
16-17
38.0-173.0
1.2-9.9
18 years and older
47-244
Not Applicable
18-30
Not Applicable
0.8-7.4
31-40
Not Applicable
1.3-9.2
41-51
Not Applicable
1.1-5.8
Postmenopausal
Not Applicable
0.6-3.8
Tanner Stage I
Less than or equal to 3.7
Less than 2.2
Tanner Stage II
0.3-21
0.4-4.5
Tanner Stage III
1.0-98.0
1.3-7.5
Tanner Stage IV
35.0-169.0
1.1-15.5
Tanner Stage V
41.0-239.0
0.8-9.2
Interpretive Data
Free testosterone concentration is calculated using total testosterone (measured by mass spectrometry) and the binding constant of testosterone and sex hormone-binding globulin (SHBG).
For individuals on testosterone-suppressing hormone therapies (e.g., antiandrogens or estrogens), refer to cisgender female reference intervals. For a complete set of all established reference intervals, refer to ltd.aruplab.com/Tests/Pub/0081059.
Laboratories.