Result Test Name
QUEST ALBUMIN
Laboratory
QUEST LAB
Result Test Code
1230910238
Laboratory Test Name
QUEST TESTOSTERONE FREE BIOAVAILABLE AND TOTAL MALES (ADULT) IMMUNOASSAY
Reportable Test Name
-
Result LOINC
1751-7
Collection Container
SST
Units
-
Collection Requirements
2 mL serum collected in a red-top tube (no gel) Alternative Specimen(s) Serum Separator Tube (SST?) Minimum Volume 1.5 mL Collection Instructions Dietary supplements containing biotin may interfere in assays and may skew analyte 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.
Container Temp
Room Temperature (1)
Container Volume
1.500
Test Info
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.
Shipping Instructions
Transport Container Transport tube Transport Temperature Room temperature Specimen Stability See individual tests Reject Criteria See individual tests