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Testosterone is the predominant "male" hormone or androgen made in the human body, although both men and women need and utilize testosterone.
In men, testosterone is made in the testes. It plays a major role in regulating sperm production and is active throughout the body, impacting many areas of health including bone and muscle health/mass, libido, fat distribution, heart health, blood sugar metabolism, and hair growth/distribution. Testosterone declines with age in both men and women, but its level can also go up or down for other reasons.
After age 40, men lose about 1.5 percent of their testosterone production each year, and by age 45 about 40 percent of men will have a diagnosable low testosterone level (too low for their age and producing symptoms). Other causes of low testosterone levels in men include diseases of the liver or kidney, injury or infection of the testicles, diabetes, insulin resistance, obesity, genetic disorders (such as Klinefelter syndrome or hereditary hemochromatosis), pituitary tumors, and some prescription medications.
Women also need testosterone in small quantities to maintain good reproductive health. In women, testosterone is made in the ovaries and the adrenal glands, so a low level of testosterone can indicate a problem with the function of either organ, or it can be indicative of a normal decline from aging. Testosterone has many protective functions in females, including mitigating bone and muscle mass loss, supporting weight management, helping to maintain mental health, and supporting a healthy libido.
On the other hand, a woman's testosterone level can be too high, particularly in women of childbearing age. An elevated testosterone level, often coupled with a low sex-hormone binding globulin level, is often associated with polycystic ovary syndrome (PCOS) and infertility.
Sex Hormone-Binding Globulin (SHBG)
Having a normal SHBG level is an important part of having a normal testosterone level in both men and women. SHBG is a protein that attaches to circulating testosterone and carries it around the body. Every individual always has some portion of their testosterone that is bound to SHBG, as well as a portion of their testosterone that is unbound or "free." SHBG can also bind to estrogen, although it does not bind as tightly as it does to testosterone.
An elevated SHBG level will result in more of it attaching to testosterone, thus lowering the amount of free testosterone, whereas a low SHBG level can present as having relatively higher "free" testosterone.
Because SHBG is produced in the liver, its level can be decreased as a result of heavy alcohol consumption, obesity, insulin resistance, diabetes, aging, and the use of some prescription medications (especially hormones such as testosterone or estrogen).
In men, if your testosterone level and/or SHBG level are abnormal for your age, then you can experience one or more of the following symptoms:
- Heightened or reduced libido
- Erectile dysfunction
- Infertility or low sperm count
- Muscle loss and/or weakness
- Depressed mood or increased aggression
- Weight gain
- Changes in body and facial hair, or male pattern baldness
- Development of breast tissue
- Metabolic syndrome
In women, if your testosterone level and/or your SHBG level are abnormal for your age and menstrual status, then you can experience one or more of the following symptoms:
- Decreased libido
- Muscle weakness or fatigue
- Depressed mood
- Weight gain
- Facial hair growth or thinning head hair
- Difficulty getting pregnant
- High cholesterol
- Metabolic syndrome
- Abnormal menstrual cycles Test
You should take this test if you
- Notice unfavorable changes in body composition
- Have loss of libido
- Are a male experiencing erectile dysfunction
- Are a female taking hormone replacement or using hormones for birth control
- Are experiencing chronic fatigue or mood swings
- Are a man or woman over 40
- Are a woman of childbearing age with fertility issues
- Are experiencing abnormal hair growth or loss
Testosterone is the predominant androgen or “male hormone” – although it is important to the health of both men and women. Testosterone impacts a wide range of health concerns, including muscle and bone mass, libido, hair growth, energy, mood, and sleep.
Sex hormone-binding globulin (SHBG) is a protein produced in the liver that binds to testosterone (and estrogen to a lesser extent). The extent of this binding by SHBG will change the amount of “free” or bioavailable testosterone, and thus can result in a deficiency or an excess of free testosterone. A low SHBG level is also associated with other health risks, independent of its impact on testosterone.