Testosterone, Free, Bioavailable and Total, Males (Adult), Immunoassay
Quest Diagnostics
Sample type: Serum
Requires fasting: No
Phlebotomy required
Details
Testosterone, Free, Bioavailable and Total, Males (Adult), Immunoassay - This test panel may be helpful in assessing androgen status and screening for hypogonadism in men. This immunoassay cannot accurately measure the low testosterone levels generally found in women, children, and men with hypogonadism.
- Testosterone, Free
- Albumin
- Testosterone, Total
- Sex Hormone Binding Globulin (SHBG)
- Testosterone, Bioavailable
Estimated days for results: Results should be available in 2 - 5 business days after the sample is collected
Details
Testosterone, Free, Bioavailable and Total, Males (Adult), Immunoassay - This test panel may be helpful in assessing androgen status and screening for hypogonadism in men. This immunoassay cannot accurately measure the low testosterone levels generally found in women, children, and men with hypogonadism [1].
Testosterone circulates in 3 major forms: unbound (free), weakly bound to albumin, and tightly bound to sex hormone-binding globulin (SHBG). Free testosterone comprises 2% to 4% of total testosterone and is biologically active. Albumin-bound testosterone can dissociate from albumin in capillaries and become available to tissue. Thus, bioavailable testosterone refers to free testosterone plus albumin-bound testosterone. In this panel, free testosterone and bioavailable testosterone concentrations are calculated based on measurements of total T, SHBG, and albumin.
In men, fasting total testosterone concentrations measured in the morning are recommended for screening for hypogonadism [2]. In patients with conditions affecting SHBG concentrations or when total testosterone levels are near the lower limit, free testosterone levels may be more sensitive than total testosterone levels for assessing androgen status. When the total testosterone level is low, or the total testosterone level is normal but free testosterone is low, the fasting total testosterone should be confirmed on another morning [2]. This test may also be used to monitor testosterone replacement therapy.
Direct immunoassays cannot accurately quantify low concentrations of testosterone, especially concentrations under the lower limit of the normal range for men [1]. Chromatography/mass spectrometry is preferred for quantifying testosterone levels in children, women, or men with low testosterone levels [1]. Further studies are needed to elaborate the use of bioavailable testosterone concentrations.
Note: Dietary supplements containing biotin may interfere with this assay. Please refer to the collection instructions for more information.
The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.
References
1. Rosner W, et al. J Clin Endocrinol Metab. 2007;92(2):405-413.
2. Bhasin S, et al. J Clin Endocrinol Metab. 2018;103(5):1715-1744.
1. Rosner W, et al. J Clin Endocrinol Metab. 2007;92(2):405-413.
2. Bhasin S, et al. J Clin Endocrinol Metab. 2018;103(5):1715-1744.
What type of sample is required for this test?
2 mL serum collected in a red-top tube (no gel)
Test Resources
For more information, please consult your healthcare provider.
2–5 business days
Testosterone, Total, Males (Adult), Immunoassay
Male: 250–827 ng/dL
Female: Not applicable
Albumin: 3.6–5.1 g/dL
Sex Hormone Binding Globulin
Age Male (nmol/L) Female (nmol/L)
<3 Years Not established Not established
3–9 Years 32–158 32–158
10–13 Years 20–166 24–120
14–17 Years 20–87 12–150
18–55 Years 10–50 17–124
>55 Years 22–77 14–73
Free Testosterone
Age Male (pg/mL) Female
18–69 Years 46.0–224.0 Not applicable
>69 Years 6.0–73.0 Not applicable
Bioavailable Testosterone
Age Male (ng/dL) Female
18–69 Years 110.0–575.0 Not applicable
>69 Years 15.0–150.0 Not applicable
Male: 250–827 ng/dL
Female: Not applicable
Albumin: 3.6–5.1 g/dL
Sex Hormone Binding Globulin
Age Male (nmol/L) Female (nmol/L)
<3 Years Not established Not established
3–9 Years 32–158 32–158
10–13 Years 20–166 24–120
14–17 Years 20–87 12–150
18–55 Years 10–50 17–124
>55 Years 22–77 14–73
Free Testosterone
Age Male (pg/mL) Female
18–69 Years 46.0–224.0 Not applicable
>69 Years 6.0–73.0 Not applicable
Bioavailable Testosterone
Age Male (ng/dL) Female
18–69 Years 110.0–575.0 Not applicable
>69 Years 15.0–150.0 Not applicable
Dietary supplements containing biotin may interfere in assays and may skew results to be either falsely high or falsely low. For patients receiving the recommended daily doses of biotin, draw samples at least 8 hours following the last biotin supplementation. For patients on mega-doses of biotin supplements, draw samples at least 72 hours following the last biotin supplementation.
Blood Draw Options with Fullscript
Fullscript offers several convenient phlebotomy options to complete your lab testing:
Quest Diagnostics Patient Service Centers (PSC)
- Location: Visit a nearby Quest Diagnostics Patient Service Center.
- Cost: $10 sample collection fee (paid during lab order checkout).
- Scheduling: Schedule your appointment here. Appointments are recommended to reduce wait times. Walk-ins are accepted, but may experience delays. Aim to arrive 10 minutes before your appointment.
- Collection Instructions:
- Bring a valid ID.
- Bring your digital or printed requisition form, available in the Labs tab of your Fullscript account.
- Check-in: Scan the QR code from your confirmation email or follow kiosk instructions.
- More Info: Quest Diagnostics blood draw guide
Getlabs Mobile Phlebotomy
- Location: Sample collection at your home or office.
- Cost: $85 sample collection fee (paid during lab order checkout).
- Availability: Available in most locations – enter your ZIP code during checkout to confirm.
- Scheduling: Schedule your appointment here through your Fullscript account.
- Collection Instructions:
- Have your digital or printed requisition form and valid ID ready.
- Your phlebotomist will contact you by phone to coordinate arrival.
- More Info: Getlabs blood draw guide
Specimen
- Preferred Specimen(s): 2 mL serum collected in a red-top tube (no gel)
- Alternative: NA
- Minimum Volume: 1.5 mL
- Collection Instructions: NA
Storage and shipping instructions
- Transport Container: Transport tube
- Transport Temperature: Room Temperature
- Specimen Stability:
- Room temperature: 5 days
- Refrigerated: 7 days
- Frozen: 21 days
- Reject Criteria: NA
State restrictions:
Patient can't order this test if they are located in Hawaii, Puerto Rico, New Jersey, New York, or Rhode Island
