What is the purpose of this test?
Order this Testosterone, Free, Bioavailable and Total Blood Test, LC/MS/MS, which measures free, bioavailable, and total testosterone levels in the blood to screen for conditions related to hormone imbalance. Total testosterone circulates primarily as protein-bound (approximately 60% bound to sex hormone binding globulin (SHBG) and 50% to albumin). Only 2-3% exist in free, biological active form. Testosterone is weakly bound to albumin and can be reversed easily. Therefore, albumin-bound and free testosterone are bioavailable testosterone—the highest levels peak at 30 to 40 in adult men. The levels decline steadily after the fourth or fifth decade of adult male life. Decreased levels of testosterone and free testosterone indicate partial or complete hypogonadism. Therefore, it is essential to determine if low testosterone levels are due to aging or a pathological disorder. In men, testicular or androgen abuse might be suspected if testosterone levels exceed the upper limit of the normal range by more than 50%.
This test may be used to evaluate the following conditions:
- Infertility, erectile dysfunction, or osteoporosis in men.
- Hirsutism, polycystic ovarian disease, and virilization in women.
- The test may also be used to monitor the efficacy of testosterone-lowering therapies in prostate cancer.
What causes abnormal testosterone levels?
Several underlying health factors may affect testosterone levels. For example, testosterone levels are affected by an individual's sex and age. Although testosterone levels decrease with age for men, abnormally low levels may indicate a testosterone deficiency. Additionally, low levels of testosterone in men can be related to other health issues, including:
- Changes in thyroid function
- Genetic or chronic illness
- Benign tumors
- Problems with the testicles
- Obesity
- Disturbed sleep
However, for women, abnormal testosterone levels may indicate excess testosterone production by the ovaries or other glands that produce sex hormones. For instance, abnormal testosterone results may be caused by the following:
- Polycystic ovary syndrome (PCOS)
- Cancer of the ovary or adrenal gland
- Pituitary gland disorder
When should I order a Testosterone, Free, Bioavailable and Total Blood Test, LC/MS/MS?
Individuals may order this test if they have experienced the symptoms related to a testosterone excess or deficiency. Common signs or symptoms of a testosterone excess or deficiency may include:
- Early or delayed puberty
- Erectile dysfunction (ED)
- Fertility problems
- Osteoporosis or thinning of the bones
- Decrease in sex drive
- Irregular periods
- Loss of periods
- Changes in hair growth patterns
- Voice changes
- Oily skin or acne
LC Sample ReportQD Sample Report
Test Code(s):
14966, 070282
Also Known As:
Free & Weakly Bound
Preparation:
No special preparation is required.
Test Results:
5-7 days. May take longer based on weather, holiday, or lab delays.
Details:
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This test includes the following:
- Testosterone, Total, LC/MS (LabCorp Only)
- Testosterone, % Free + Weakly Bound (LabCorp Only)
- Testosterone, F + W Bound (LabCorp Only)
- Testosterone, Total, MS (different from ""LC/MS"") (Not Included with LabCorp)
- Testosterone, Free (not listed as “% Free + Weakly Bound”) (Not Included with LabCorp)
- Testosterone, Bioavailable (not listed in LabCorp) (Not Included with LabCorp)
- Sex Hormone Binding Globulin (SHBG) (Not Included with LabCorp)
- Albumin (Not Included with LabCorp)
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