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Testosterone replacement therapy (TRT) is a
treatment for low testosterone, also known as male hypogonadism. Testosterone is a sex hormone
that’s essential for the body; it’s produced in the testicles. In men, it’s necessary for:
TRT increases the levels of testosterone in
your blood using testosterone that was manufactured in a lab. The goal is to reach and maintain
normal testosterone levels while relieving symptoms of low-T and improving your quality of
TRT is used by around
0.9-2.9% of cis men in the US, and its usage continues to grow. There are both potential
benefits and risks to TRT. Current research supports
treating younger individuals who have low testosterone. However, using it for older adults, where
low testosterone is a common condition, is still under debate.
A form of testosterone therapy can also be used by trans men to develop and maintain
typically masculine features. In this article, we’ll be primarily discussing people who
testosterone level for most men is between 300
ng/dL and 1,000 ng/dL, when measured via a blood test in the morning. (Testosterone should
always be measured between 7 and 11
am, since this is when it’s at its highest level.) Younger men typically have a testosterone
level of 600–900 ng/dL while older men are around 500–800 ng/dL.
Low testosterone, also called low-T or male hypogonadism, occurs when your body produces an
insufficient amount of the testosterone hormone. In middle-aged and older men, it’s referred to as
Research indicates that around
39% of men aged 45 or above experience hypogonadism, but only between 5 and 35% of them are treated.
There are two types of
hypogonadism, which can be categorized depending on their cause. If you have low testosterone, you
may have either one or both types.
After a blood test has confirmed low testosterone levels, measuring your LH and FSH levels can help
identify whether you have primary or secondary hypogonadism.
If you have low-T, you may have
no symptoms, or they may include:
Many of these symptoms may be similar to those caused by other conditions (like high blood
pressure) or by older age. This can make them difficult to notice and treat.
Low testosterone may
be suspected due to symptoms, and confirmed with blood testing. A blood test will measure the main types
“Total testosterone” is, as it sounds, the total of all three types of testosterone.
You may be diagnosed with hypogonadism if you have less than 300 ng/dL of total testosterone in your
blood after repeated testing, and show at least one other symptom.
You may also receive a diagnosis of hypogonadism if your total testosterone levels are normal, but
you still have symptoms. In fact, research
suggests that low levels of free testosterone may be linked to erectile dysfunction, even if total
testosterone levels are within the standard range.
If you have low testosterone,
increasing your testosterone levels to the normal range can improve low-T symptoms, resulting in:
Improvements in sex drive and mood typically occur soon after beginning TRT. You’ll likely experience
a decrease in body fat and increased bone mineral density within 6 months of starting
treatment. You may continue to see benefits after a longer period of TRT.
If your symptoms don’t show improvement after 3 months of TRT, your
doctor will likely reevaluate the potential causes behind your condition.
evidence about the potential side effects of testosterone replacement therapy, especially when used
long-term. The following are possible issues:
Testosterone replacement therapy may have additional side effects, but more research is needed to
confirm them. These include possible increased risks of heart attack and cancer.
Using TRT comes with a potential
increased risk of heart attack, stroke, and myocarditis (inflammation of the heart). As research has
particularly linked this issue to older men, it’s an important factor to take into account for TRT
patients over the age of 55, who are already at increased risk.
A large 2014 study
found an increased risk of heart attack in men aged 65 and above as well as in younger men with
heart disease after taking TRT. The study noted that taking testosterone may increase blood clotting
and blood pressure, which may contribute to heart attacks.
Another study also showed a higher chance of
negative cardiovascular events among older men who were using testosterone gel. Many of these men
also had other chronic diseases.
On the other hand, some recent research
has suggested that TRT may reduce cardiovascular risks in men with very low testosterone levels.
Compared to participants who did not receive treatment, men younger than 55 who used TRT had a 25%
lower chance of heart attack and stroke, while men over 60 on TRT had a 15% lower risk. The men
using TRT also had health improvements in other areas.
In another study,
testosterone was even used as a treatment for cardiovascular issues, improving exercise capacity in
men with heart failure. Only 24% of participants had low testosterone levels when they began the
More research is needed to evaluate the risk of TRT on heart conditions. For the moment, the FDA
requires that prescription testosterone product labels include warnings of the potential higher
chance of strokes and heart attacks. It’s important to seek immediate medical care if you experience
any of the following, particularly while taking testosterone:
There’s some concern
that TRT may heighten the risk of prostate cancer because testosterone promotes the growth of prostate
cancer cells. However, little, if any,
research supports this. While more research should be done in this area, multiple studies and
analyses indicate that TRT does not impact prostate cancer risk.
A recent study of over 12,000
men with late-onset hypogonadism found that using TRT was not linked to a higher chance of prostate
cancer. All of the men were at least 45 years old with no history of prostate cancer, and many had a
follow-up period of multiple years.
Research from 2017 also found no
elevated risk of prostate cancer, even after participants received TRT for a longer period. In fact,
those who took TRT had a lower chance of aggressive prostate cancer.
Similarly, a meta-analysis indicated that
using TRT did not cause an increase in prostate cancer compared to controls. It also found no
increase in prostate-specific antigen (a marker that tends to be elevated when prostate cancer is
present) related to TRT, except for a slight increase with testosterone injections.
More research is needed to confirm the link, or lack thereof, between TRT and cancer. It’s currently
recommended that individuals receiving
TRT undergo regular checks for prostate cancer. Additionally, you shouldn’t use TRT if you already
have prostate cancer.
Studies show that prescriptions of TRT
for off-label use have expanded, leading to patients receiving prescriptions for testosterone
even if they don’t have hypogonadism or if blood testosterone levels have not been assessed. In
up to around
25% of cases, men receiving testosterone may not have had their testosterone levels
checked before starting therapy. As of 2017, 3
out of 1,000 male military service members were being inappropriately treated with TRT.
People may also take testosterone without receiving a prescription. Anabolic-androgenic
steroids contain synthetic versions of testosterone that can be injected into muscles, taken
orally, or used as a gel or cream. Some athletes — primarily men — use these steroids to
enhance their physical performance or build muscle mass.
Testosterone is an important treatment for
some medical conditions, but it shouldn’t be taken recreationally. Non-medical doses can be 10 to 100
times higher and may lead to a range of health problems, including:
Using anabolic-androgenic steroids may also reduce natural testosterone production. According
to research, previous
use of steroids is the most common cause of profound hypogonadism — nearly non-existent
testosterone levels — in men under 50.
Testosterone plays an essential role
in spermatogenesis (sperm production), primarily through helping control processes including meiosis
(cell division) and the release of mature sperm. However, testosterone levels are between 25 and 125 times higher in the
testes than in the blood, so even if you have low blood testosterone levels, you still likely have
enough for sperm production.
Testosterone is an important hormone for male fertility, but boosting your testosterone levels
doesn’t translate to increased fertility. In fact, the opposite is true. Injecting exogenous
(external) testosterone will disrupt the hormone balance and actually halt sperm production —
something that’s important to consider if you’re interested in trying TRT.
Several parts of your body work together to
keep your reproductive system functioning normally. This system is called the hypothalamic-pituitary-gonadal
An area of your brain called the hypothalamus releases gonadotropin-releasing hormone (GnRH),
which stimulates the pituitary gland to release follicle-stimulating hormone (FSH) and
luteinizing hormone (lH). In turn, FSH and LH impact the functions of the testicles. FSH
controls the maturation and function of Sertoli cells, which play a critical role in sperm
production. Meanwhile, LH is needed for the testes to make testosterone.
Finally, the testosterone created by the testicles does a “feedback loop” back to the brain
to turn on — or off — GnRH, FSH, and LH production. This is one of many hormone “cascades”
in the human body.
Changes within the system affect other parts of it. When you increase your blood testosterone
levels by taking testosterone, your hypothalamus and pituitary glands respond by shutting
down production of the hormones that are vital for sperm production. Research
shows that TRT causes suppression of FSH and LH to abnormally low levels — less than
one-half of their original levels in the men studied.
exogenous testosterone reduces FSH and LH, it also impairs sperm production and fertility. Testosterone
has actually been studied for use as a male contraceptive, resulting in azoospermia
(lack of sperm in semen) within 4 months in 65% of men with previously
normal sperm counts.
While TRT can improve sexual function, it also reduces fertility, presenting a difficult choice for
individuals with symptoms of hypogonadism who want to have children. If you’re currently trying to
conceive, you should not use TRT or should stop using it immediately. You can also consider sperm freezing before TRT.
Because the dose of
testosterone in anabolic
steroids is so high, it’s been shown to permanently halt sperm and testosterone production in
However, TRT is typically a much lower dose, and is therefore not likely to permanently affect your
fertility. Research shows that sperm production typically recovers within 1 year after men stop taking
testosterone; in some men, it may take as long as 2 years. However, restored
sperm counts aren’t a guarantee, and are less understood for older individuals and those using TRT
long term. One to two years may also be longer than some people wish to wait to conceive.
It may be possible to reduce the
impact of TRT on fertility. Human
chorionic gonadotropin (hCG), also known as the “pregnancy hormone” because it’s produced during
pregnancy, mimics the effect of LH in the body, prompting the testes to continue to produce their own
Taking hCG alongside TRT may help offset the effect of exogenous testosterone on sperm production. Research has indicated that taking hCG
alongside TRT maintained intratesticular testosterone at normal levels, though it noted that more
studies need to be done on sperm production under these conditions. A subsequent study examined this issue, finding that
hCG seemed to preserve semen parameters, and potentially fertility, during TRT.
Taking hCG may also allow for a quicker restoration of sperm counts following TRT. According to one
study of men who
had very low sperm counts while using testosterone, taking 3,000 units of hCG every other day after
stopping TRT improved sperm counts in 95.9% of participants over an average of 4.6 months — a
shorter period than typically achieved without hCG.
Your doctor may prescribe hCG along with TRT. However, it’s once again not guaranteed to preserve or
recover sperm production.
If you’ve been diagnosed with low-T and you
want biological children in the future, the best thing you can do to protect your fertility
options is to freeze some sperm. Sperm freezing is the process of using liquid nitrogen to
preserve one or more sperm samples for possible use later on.
It’s a fairly simple process. First, you produce a semen sample via masturbation. This sample
is then assessed under a microscope in a semen analysis, to determine
if your sperm are healthy and viable for freezing. Finally, sperm are plunged into liquid
nitrogen to freeze them at a temperature of -196ºC — the temperature at which biological
activity pauses — and transferred to liquid nitrogen storage tanks to maintain their low
Once frozen, your sperm can be stored indefinitely without a decrease in quality or
likelihood that it will create a pregnancy. Frozen sperm can be used in intrauterine
insemination (IUI), the “turkey baster” method, as well as IVF, a process in which eggs and
sperm are combined outside the body in a lab. Learn more about sperm
Legacy makes the sperm
freezing process even easier with at-home semen analysis and sperm freezing kits.
According to the FDA,
TRT should only be used by men whose low testosterone levels are a result of medical conditions. Doctors
sometimes prescribe testosterone therapy for individuals who have lower testosterone due to their age,
and some research as well as the 2018 Endocrine Society Clinical
Practice Guidelines support this for men over 65 who have both low testosterone levels and
related symptoms. However, you should be aware that this is currently not an approved use by the FDA.
TRT may be a good option for you if:
You should not start TRT if you have: