Low Testosterone & TRT: Benefits, Risks | Dr. Theodore Cisu

The short answer: Low testosterone, which doctors call testosterone deficiency, means low testosterone levels in the blood together with symptoms such as low sex drive, weaker erections or low energy. The AUA guideline calls for two early-morning blood tests on different days to confirm it. Testosterone therapy can help some symptoms, but it needs ongoing monitoring. It also lowers sperm production, so men who want children need a different plan.

Written by Theodore Cisu, MD, board-certified urologist. Based on the American Urological Association (AUA) guideline on the evaluation and management of testosterone deficiency (published 2018, reviewed and reaffirmed 2024). Last reviewed November 2026.

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What is low testosterone?

Testosterone is made mainly in the testicles. A signal from the pituitary gland in the brain, called LH, tells the testicles how much to make. Levels are highest in the morning and slowly decline with age.

Low testosterone can start in the testicles themselves, or in the brain signals that control them. The AUA guideline is clear that a low number alone isn't enough for a diagnosis. You need both low levels and symptoms or signs that fit.

Symptoms of low testosterone

• Low sex drive
• Weaker erections or fewer morning erections
• Low energy and fatigue
• Low mood or irritability
• Loss of muscle and more body fat
• Less body hair, or hot flashes
• Mild anemia or thinning bones found on testing

These symptoms overlap with poor sleep, stress, depression, thyroid problems and other conditions. That is why testing matters before starting treatment.

What causes low testosterone?

• Aging
• Extra weight and type 2 diabetes
• Untreated sleep apnea
• Opioid pain medicines
• Past use of anabolic steroids
• Pituitary problems, including high levels of a hormone called prolactin
• Testicle injury, past chemotherapy or radiation, or genetic conditions such as Klinefelter syndrome

How is low testosterone diagnosed?

Two morning blood tests

The AUA recommends measuring total testosterone on two separate occasions, both early in the morning. Levels swing from day to day, so one low result can be misleading. The guideline uses a total testosterone below about 300 ng/dL as a reasonable cutoff, along with symptoms.

Follow-up tests

• LH helps show whether the problem starts in the testicles or the brain.
• Prolactin is checked when LH is low or normal. A high level can point to a pituitary issue that needs further testing.
• Blood count (hematocrit) is measured before treatment, because testosterone can thicken the blood.
• PSA, a prostate blood test, is checked in men over 40 before starting therapy.
• Estradiol is checked if you have breast tenderness or enlargement.

Your urologist will also ask whether you hope to have children now or in the future. That answer shapes the treatment plan.

Treatment options

Lifestyle steps

The AUA notes that weight loss and exercise can raise testosterone in men with extra weight. Treating sleep apnea and reviewing medicines such as opioids can also help. These steps are worth doing whether or not you start therapy.

Testosterone therapy

Testosterone comes in several forms:

• Gels or creams applied to the skin each day. Wash your hands afterward and cover the area, because the medicine can rub off on women and children.
• Injections into a muscle or under the skin, at home or in the office.
• Pellets placed under the skin every few months.
• Patches, oral capsules and a nasal gel are other options.

The AUA suggests aiming for a level in the middle of the normal range. Higher isn't better. The AUA also encourages using FDA-approved products from a licensed pharmacy.

Options for men who want children

Some medicines raise your own testosterone while protecting sperm production. These include clomiphene, hCG and aromatase inhibitors such as anastrozole. Some are used off-label for this purpose. Your urologist can help you weigh them.

Benefits and risks of testosterone therapy

What it can help

For men with confirmed testosterone deficiency, the AUA describes improvements in sex drive and erections, anemia, bone density and lean muscle. Some men notice better mood. The evidence is weaker for energy, memory and blood sugar. Results vary. If symptoms don't improve after a fair trial, it's reasonable to rethink treatment.

Fertility

Testosterone therapy signals the brain to shut down the testicles' own production. That can drop sperm counts sharply, sometimes to zero. Sperm production often recovers after stopping, but it can take months and recovery isn't guaranteed. The AUA advises against testosterone therapy for men who are trying to conceive.

Heart and blood pressure

The large TRAVERSE trial studied men with low testosterone and heart risk. Men using testosterone gel did not have more heart attacks or strokes than men using a placebo. In 2025, the FDA removed heart-risk language from the boxed warning on testosterone products. The FDA also added a warning that testosterone can raise blood pressure. In TRAVERSE, a few problems, such as an irregular heart rhythm called atrial fibrillation and blood clots in the lungs, were somewhat more common with testosterone. The AUA guideline also advises waiting several months after a heart attack or stroke before starting therapy.

Prostate

The AUA guideline states there is no definitive evidence that testosterone therapy causes prostate cancer. PSA is still monitored in men over 40, and changes are followed up.

Other side effects

Acne, oily skin, breast tenderness, smaller testicles, skin irritation from gels and worsening sleep apnea can occur.

Monitoring while on testosterone

• Testosterone levels, to keep you in a healthy range
• Blood count, adjusting the dose or pausing therapy if it rises too high
• PSA and urinary symptoms, for men over 40
• Blood pressure
• How you feel, since symptom relief is the point of treatment

Checks are more frequent at first, then often every 6 to 12 months once you are stable.

When to see a urologist

• Symptoms of low testosterone, or a low result on a blood test
• You're on testosterone and want to have children
• You started testosterone elsewhere and aren't being monitored
• Rising blood count or PSA while on therapy

Seeing Dr. Cisu for low testosterone

Dr. Theodore Cisu evaluates low testosterone and offers testosterone therapy and fertility-friendly alternatives at his clinics in Charlottesville and Fishersville. You can start with a telehealth visit from anywhere in Virginia. Our office can request your prior lab results so Dr. Cisu reviews them first. Second opinions are welcome, and no referral is needed. Book a visit.

Frequently asked questions

What is a normal testosterone level for a man?

Lab ranges vary. The AUA uses a total testosterone below about 300 ng/dL, on two morning tests, as a reasonable cutoff for low testosterone when symptoms are present.

Why does my testosterone test need to be in the morning?

Testosterone peaks in the early morning and varies from day to day. Two morning tests give a more reliable picture than a single afternoon test.

Will testosterone therapy make me infertile?

It can. Testosterone lowers sperm production, sometimes to zero. If you want children now or soon, ask about alternatives such as clomiphene or hCG.

Is testosterone therapy safe for my heart?

The TRAVERSE trial found no increase in heart attacks or strokes with testosterone gel in men with low testosterone. Testosterone can raise blood pressure, though, so it is monitored. Talk with your urologist if you've had a recent heart attack or stroke.

Does testosterone cause prostate cancer?

According to the AUA guideline, there's no definitive evidence that it does. PSA is still checked before and during therapy in men over 40.

Can I stop testosterone once I start?

Yes. Symptoms usually return to where they were before treatment. Your body's own production may take time to restart, so plan the change with your doctor.

Do over-the-counter testosterone boosters work?

Most have little good evidence behind them, and supplements aren't checked by the FDA for what they contain. A proper evaluation is a better first step.

Sources

• American Urological Association. Evaluation and Management of Testosterone Deficiency: AUA Guideline (2018; reviewed and validity confirmed 2024).
• U.S. Food and Drug Administration. FDA issues class-wide labeling changes for testosterone products (2025).

This article is for general education and isn't a substitute for medical advice. Don't start or stop testosterone without talking with your doctor. If you have chest pain, sudden shortness of breath, or weakness on one side of the body, call 911.