What Is TRT? A Plain-English Guide to Testosterone Replacement Therapy

Testosterone replacement therapy, or TRT, is prescription testosterone used to bring low testosterone back into a normal range in men with diagnosed hypogonadism. It may help libido, energy, anemia, bone density, mood, and muscle mass, but it can reduce fertility, raise red blood cell counts, and worsen sleep apnea, so testing and follow-up matter.1

What is testosterone replacement therapy (TRT)?

TRT means testosterone replacement therapy, also called androgen replacement therapy. It uses manufactured testosterone to replace low levels in men with hypogonadism, which means the testes or the brain signals that control them are not making enough testosterone for a medical reason.1

The FDA has approved testosterone products for men with low testosterone caused by specific disorders of the testes, pituitary gland, or brain. The FDA has not approved testosterone for low testosterone caused only by normal aging.2

Primary hypogonadism starts in the testes. Secondary hypogonadism starts in the hypothalamus or pituitary gland, where gonadotropin-releasing hormone, or GnRH, and luteinizing hormone, or LH, help signal the testes to make testosterone.1

How does TRT work in the body?

Testosterone affects sexual function, red blood cell production, bone density, muscle protein balance, fat distribution, mood, and energy. TRT raises blood testosterone levels from a low range toward a target range chosen and monitored by the treating clinician.1

The trade-off is feedback suppression. When the body senses testosterone coming from outside, the brain often lowers GnRH, LH, and follicle-stimulating hormone, or FSH. That can reduce sperm production and shrink the testes during treatment.4

This is why TRT is different from a general “vitality” treatment. It is hormone replacement for a confirmed deficiency, not a casual way to improve gym results or offset normal aging.2

Who is a candidate for TRT?

TRT candidacy starts with symptoms and repeat lab evidence. The Endocrine Society recommends diagnosing hypogonadism only in men who have symptoms or signs of testosterone deficiency and consistently low serum testosterone levels.1

Signs and symptoms of low testosterone

Symptoms that can fit low testosterone include lower sex drive, fewer spontaneous erections, erectile dysfunction, fatigue, depressed mood, lower motivation, loss of body hair, reduced muscle mass, higher body fat, hot flashes, anemia, and low bone density.1

These symptoms are not specific. Poor sleep, untreated sleep apnea, depression, thyroid disease, alcohol use, opioid use, high stress, overtraining, obesity, and some medications can look similar, so testing and history matter.1

How doctors diagnose low T with blood testing

Most guidelines start with a fasting morning total testosterone level because testosterone has a daily rhythm and is usually highest early in the day. If the first test is low, clinicians usually repeat it on a separate morning before making the diagnosis.1

Clinicians may also check free testosterone, sex hormone binding globulin, or SHBG, LH, FSH, prolactin, thyroid labs, complete blood count, metabolic labs, and prostate-specific antigen, or PSA, depending on age, symptoms, exam, and risk factors.1

What counts as a low testosterone level?

There is no single magic number for every person. The American Urological Association guideline uses total testosterone below 300 ng/dL as a reasonable cut-off to support the diagnosis of low testosterone when symptoms are also present.5

Lab ranges vary, and SHBG can change how much active testosterone is available. That is why a clinician should interpret results in context, not from a single number alone.1

What forms does TRT come in?

Testosterone therapy comes in several forms, and each form changes how steady the level feels, how often it is used, and what risks need attention. FDA-approved testosterone options include injections, topical gels, patches, oral testosterone undecanoate capsules, and implanted pellets.3

Injections

Injectable testosterone is often prescribed as testosterone cypionate or testosterone enanthate. Some products are long acting, such as testosterone undecanoate injection, and have specific safety rules in their labeling.3

Gels and creams

Topical testosterone gels such as AndroGel and Testim are applied to the skin. FDA labels warn that testosterone can transfer to others through skin contact, so covering the area and washing hands are important label precautions.6

Patches, capsules, and pellets

Patches are changed on a schedule set by the product label and clinician. Oral testosterone undecanoate products such as Jatenzo and Kyzatrex avoid needles but carry blood pressure warnings. Pellets such as Testopel are implanted by a clinician and last longer, but they require an in-office procedure.7

What are the benefits of TRT?

TRT benefits are most likely when a man truly has hypogonadism. In the Testosterone Trials, older men with low testosterone who received testosterone gel had modest improvements in sexual activity, sexual desire, and erectile function compared with placebo, but individual results varied.9

The same research program found that testosterone improved hemoglobin in men with anemia and increased volumetric bone mineral density and estimated bone strength. These were study results, not guarantees for every patient.10

Body composition can change too. Testosterone can increase lean mass and reduce fat mass in some men with low testosterone, but that does not mean TRT is a weight-loss drug or a substitute for nutrition, resistance training, sleep, and treatment of underlying illness.11

Benefits must be weighed against risks in the same visit. TRT can raise hematocrit, worsen acne, affect sleep apnea, suppress fertility, and require prostate and cardiovascular risk review before and during treatment.1

What are the risks and side effects of TRT?

TRT risks are real, even when treatment is appropriate. The main issues clinicians monitor are fertility suppression, high hematocrit or erythrocytosis, acne or oily skin, fluid retention, breast tenderness, sleep apnea worsening, prostate monitoring changes, and cardiovascular risk.1

Fertility and testicular shrinkage

TRT can lower sperm count because outside testosterone suppresses LH and FSH signals from the brain. The Endocrine Society recommends against starting testosterone therapy in men who are planning fertility in the near term.1

Testicular shrinkage can happen for the same reason: the testes receive less signal to make testosterone and sperm. Men trying to conceive should discuss fertility-preserving options with a reproductive urologist rather than starting TRT casually.4

Cardiovascular risk

Cardiovascular safety has been debated for years. In the TRAVERSE trial, men with hypogonadism and high cardiovascular risk who received testosterone gel had a noninferior rate of major adverse cardiac events compared with placebo, but the testosterone group had higher rates of atrial fibrillation, acute kidney injury, and pulmonary embolism.12

That means the answer is not “TRT is always dangerous” or “TRT is risk-free.” It means patient selection, baseline heart risk, blood pressure, hematocrit, symptoms, and follow-up matter.12

Prostate concerns

TRT is not recommended for men with prostate cancer or breast cancer. Guidelines also call for prostate risk assessment, including PSA testing in appropriate age groups, before and during therapy.1

TRT can raise PSA in some men, which may lead to more testing. A PSA change does not automatically mean cancer, but it should be reviewed by a clinician.1

Sleep apnea, acne, and red blood cell changes

TRT can worsen untreated severe obstructive sleep apnea, so guidelines recommend against starting testosterone in that setting. Acne and oily skin can also occur because testosterone affects oil glands.1

A key lab risk is erythrocytosis, meaning the red blood cell level gets too high. Clinicians track hematocrit because high hematocrit can make blood thicker and may raise clotting risk.1

Who should not take TRT?

TRT is not appropriate for everyone. The Endocrine Society recommends against testosterone therapy in men with breast cancer, prostate cancer, a prostate nodule or concerning PSA without urologic evaluation, elevated hematocrit, untreated severe sleep apnea, severe lower urinary tract symptoms, uncontrolled heart failure, recent heart attack or stroke, thrombophilia, or plans for fertility soon.1

Men with borderline labs, unclear symptoms, or reversible causes should not rush. Treating sleep apnea, reducing heavy alcohol use, changing a medication, losing visceral fat, or addressing depression may change testosterone levels and symptoms without TRT.1

How much does TRT cost and does insurance cover it?

TRT cost varies by form, lab schedule, visit model, pharmacy, and insurance plan. In general, injectable testosterone is often less expensive than pellets or some branded oral capsules, while visits and lab monitoring add to the total cost.3

Insurance coverage often depends on documented symptoms, repeat low morning testosterone levels, diagnosis codes, prior authorization rules, and the specific product. Some plans may cover certain generic testosterone products while requiring more paperwork for brand products or procedures.3

The practical point: ask for a full estimate that separates clinician visits, labs, medication, supplies, and follow-up. A low medication price can still become costly if labs and visits are not included.

How does TRT compare with other ways to support testosterone and vitality?

TRT replaces testosterone when a true deficiency is present. Lifestyle steps and related therapies may support health, energy, body composition, or recovery, but they are not the same as replacing testosterone in confirmed hypogonadism.1

At Chia, we are careful not to blur these categories. Men often ask us about energy, sleep, body composition, and vitality, and sometimes the right next step is a broader evaluation rather than a testosterone prescription.

How can you get evaluated for symptoms through a telehealth clinic like Chia?

Chia does not currently prescribe testosterone. TRT information here is educational only. If your symptoms suggest possible hypogonadism, a licensed clinician should confirm the diagnosis with repeat morning blood testing and decide whether referral, in-person care, or hormone treatment is appropriate.1

What we can do is help patients think clearly about overlapping goals like energy, recovery, body composition, and healthy aging. Through Chia, patients can start with a short online health questionnaire, then a licensed US provider reviews it and prescribes only when clinically appropriate.

For treatments Chia does offer, such as sermorelin, NAD+, glutathione, and certain GLP-1 options, medications are compounded in the US by state-licensed 503A pharmacies and shipped to the patient’s door when prescribed. Dosing is provider-guided and adjusted over time through the patient portal.

If you want a clinician-reviewed starting point for your goals, you can begin with Chia’s online eligibility quiz. A prescription is never guaranteed, and if your answers point toward possible low testosterone, we may suggest appropriate testing or referral rather than a Chia-offered treatment.

What should you ask a clinician before starting TRT?

Before TRT, the best questions are simple: Do my symptoms and labs truly fit hypogonadism? What is the likely cause? What risks apply to me? How will fertility, hematocrit, PSA, blood pressure, sleep apnea, and follow-up be monitored?1

• Have I had two separate morning testosterone tests, not just one random lab?1
• Do we need free testosterone, SHBG, LH, FSH, prolactin, thyroid testing, or iron studies to understand the cause?1
• Am I trying to conceive now or soon? If yes, TRT may not be appropriate because it can lower sperm production.1
• Do I have untreated severe sleep apnea, high hematocrit, prostate cancer, breast cancer, recent heart attack or stroke, or uncontrolled heart failure?1
• Which form fits my life, and what labs or visits are included in the plan?

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