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HelpOrder Code LABFFTST Testosterone, Free and Weakly Bound, With Total Testosterone, LC/MS-MS
Additional Codes
Mayo Test Code: FFTST
EPIC Test Code: LABFFTST
Specimen Required
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/tube: Plastic vial
Specimen Volume: 2 mL
Collection Instructions:
1. Within one hour of collection, centrifuge and aliquot 2 mL serum into a plastic vial.
2. Ship refrigerated.
Method Name
Ammonium sulfate precipitation; liquid chromatography/tandem mass spectrometry (LC/MS-MS)
Reporting Name
Testosterone,F/WklyBd+T LC/MSSpecimen Type
SerumSpecimen Minimum Volume
1.4 mL (does not allow for repeat testing)
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 7 days |
| Ambient | 7 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
| Gross icterus | OK |
Reference Values
Males:
|
Age: |
Range (ng/dL): |
|
Premature Infants (26 to 28 weeks) Day 4 |
59.0-125.0 |
|
Premature (31-35 weeks) Day 4 |
37.0-198.0 |
|
Newborns |
75.0-400.0 |
|
Prepubertal (1 to 10 years) |
<2.5-10.0 |
1 to 7 Months
Levels decrease rapidly the first week to 20.0-50.0 ng/dL, then increase to 60.0-400.0 ng/dL (mean=190.0) between 20-60 days. Levels then decline to prepubertal range of <2.5-10.0 by seven months.
Females:
|
Age: |
Range (ng/dL): |
|
Premature Infants (26 to 28 weeks) Day 4 |
5.0-16.0 |
|
Premature (31-35 weeks) Day 4 |
5.0-22.0 |
|
Newborns |
20.0-64.0 |
|
Prepubertal (1 to 9 years) |
<2.5-10.0 |
1 to 7 Months
Levels decrease during the first month to <10.0 ng/dL and remain there until puberty.
Puberty:
|
Tanner Stage (Males) |
Age (Years) |
Range (ng/dL) |
Mean (ng/dL) |
|
1 |
<9.8 |
<2.5-10.0 |
4.9 |
|
2 |
9.8-14.5 |
18.0-150.0 |
42.0 |
|
3 |
10.7-15.4 |
100.0-320.0 |
190.0 |
|
4 |
11.8-16.2 |
200.0-620.0 |
372.0 |
|
5 |
12.8-17.3 |
350.0-970.0 |
546.0 |
|
Tanner Stage (Females) |
Age (Years) |
Range (ng/dL) |
Mean (ng/dL) |
|
1 |
<9.2 |
<2.5-10.0 |
4.9 |
|
2 |
9.2-13.7 |
7.0-28.0 |
18.0 |
|
3 |
10.0-14.4 |
15.0-35.0 |
25.0 |
|
4 |
10.7-15.6 |
13.0-32.0 |
22.0 |
|
5 |
11.8-18.6 |
20.0-38.0 |
28.0 |
Adults:
|
≥18 Years |
Range (ng/dL) |
|
Males |
350.0-1030.0 |
|
Females |
|
|
Premenopausal |
10.0-55.0 |
|
Postmenopausal |
7.0-40.0 |
Testosterone % Free+Weakly Bound:
Female: 3.0-18.0%
Male: 9.0-46.0%
Testosterone, F+W Bound:
Female: 0.0-9.5 ng/dL
Male: 40.0-250.0 ng/dL
Day(s) Performed
Daily
Performing Laboratory
LabCorp BurlingtonCPT Code Information
84410
Useful For
Free and weakly bound testosterone (FWBT), also referred to as bioavailable testosterone, is thought to reflect an individual's biologically active, circulating testosterone. FWBT includes free testosterone and testosterone that is bound to albumin. FWBT does not include sex hormone-binding globulin-bound testosterone. The SHBG-bound fraction is biologically inactive because of the high binding affinity of SHBG for testosterone. The rapid dissociation of "weakly bound" testosterone from albumin results in the availability of essentially all albumin-bound testosterone for steroid-receptor interaction.(1)