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Testosterone is a powerful hormone, with the ability to control sex drive, regulate sperm production, promote muscle mass, increase energy, and even influence human behavior (such as aggression and competitiveness). It’s no wonder that a decrease in testosterone would cause quite a stir. However, it is a natural part of aging.
Testosterone plays an important role in shaping the developing fetus during pregnancy. It drives the development of the male reproductive system. Testosterone also masculinizes the brain.
However, testosterone levels have to fall within a very narrow margin in order for the fetal brain to be healthy. High levels of fetal testosterone may be linked to autism. Other research has found that low levels of fetal testosterone may boost your chances of getting Alzheimer’s disease later in life.
Testosterone levels are at their highest during adolescence and early adulthood. The first physical signs of testosterone, or androgens, in the body are apparent during puberty. A boy’s voice changes, his shoulders broaden, and his facial structure becomes more masculine. But as men get older, their testosterone levels decline about 1 percent per year after age 30.
This chart breaks down the normal ranges of testosterone by age and gender, according to the Mayo Clinic:
|Age:||T Level (ng/dL):||Age:||T Level (ng/dL):|
|0-5 mo.||75-400||0-5 mo.||20-80|
|6 mos.-9 yrs.||< 7-20||6 mos.-9 yrs.||< 7-20|
|10-11 yrs.||< 7-130||10-11 yrs.||< 7-44|
|12-13 yrs.||< 7-800||12-16 yrs.||< 7-75|
|14 yrs.||< 7-1,200|
|17-18 yrs.||300-1,200||17-18 yrs.||20-75|
|19+ yrs.||240-950||19+ yrs.||20-75|
|Avg. adult male||270-1,070||Avg. adult female||15-70|
|30+ yrs.||-1% per year|
Testosterone is often thought of as the "fountain of youth" hormone. But naturally declining testosterone levels don’t cause signs and symptoms of aging, according to the Mayo Clinic.
However, low testosterone levels can cause changes in sexual function, including:
Other signs of decreased testosterone levels include:
The normal range of testosterone levels in healthy adult males is between 280 to 1,100 nanograms per deciliter (ng/dL), reports the University of Rochester Medical Center. It’s important to determine if a low testosterone level is due to normal aging or if it’s due to a disorder.
Testosterone levels affect women as well. However, women create lower levels and are more sensitive to androgens than men. Testosterone levels in women vary. According to the University of Rochester Medical Center, normal measurements range from 15 to 70 ng/dL.
Excess androgens in a woman’s blood stream can cause obvious physical effects, including:
Testosterone deficiency, on the other hand, can cause fertility problems, weak bones, and loss of libido.
While the symptoms described here are considered a normal part of aging, they could also be signs of several underlying factors. These include:
According to Mayo Clinic, the best way to diagnose low testosterone is to visit your doctor for a blood test. The University of Rochester Medical Center suggests that the best time of day to have a blood sample taken for a testosterone test is around 8 a.m. Results outside of the normal range could be caused by conditions like:
It’s natural to be concerned about lower levels of testosterone. However, a gradual decrease is a normal part of aging. Talk to your doctor if you’re worried that there could a different cause.
Written by: Alexia Severson and R. Sam Barclay
Medically reviewed on: Mar 23, 2015: Steven Kim, MD
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