Low testosterone and TRT: separating the symptoms from the marketing

Testosterone is the primary male sex hormone, but its job description is much broader than the name suggests. It is produced mostly in the testes (about 95%) under signals from the brain — specifically, the hypothalamus releases GnRH, which prompts the pituitary to release LH and FSH, which travel to the testes and stimulate testosterone production. This brain-to-testes loop is called the hypothalamic-pituitary-gonadal axis, and it is the system that responds to feedback from circulating testosterone levels.

Testosterone influences libido and sexual function, sperm production, muscle mass and strength, bone density, fat distribution, red blood cell production, mood and cognitive function, and the regulation of metabolic health. It is not the only thing that matters for any of these — sleep, stress, diet, and other hormones all play roles — but it is one of the more measurable contributors.

Levels naturally fall with age. Average total testosterone in healthy men in their 20s sits around 600–700 ng/dL, falls roughly 1–2% per year starting in the 30s, and reaches a population average of around 400–500 ng/dL in the 60s. This gradual decline is normal and does not, by itself, mean low T or require treatment.

Testosterone follows a daily rhythm — it is highest in the early morning, drops through the day, and is lowest in the evening. A reading that is "low" at 4 p.m. may be perfectly normal at 8 a.m. The Endocrine Society guidance on diagnosing low T is explicit about this: a proper workup requires two separate morning serum total testosterone tests (ideally before 10 a.m.), drawn on different days, both showing a result below the lower end of the normal range — usually around 300 ng/dL.

And numbers alone are not sufficient. The same Endocrine Society guidance specifies that the diagnosis of male hypogonadism requires both consistent symptoms (low libido, ED, fatigue, loss of morning erections, mood changes, decreased muscle mass) AND confirmed low testosterone on at least two morning draws.

A single low afternoon test, ordered at a walk-in clinic or via a direct-to-consumer lab service, is not a diagnosis. It is a starting point — or, in the worst case, the beginning of a sales pitch for therapy you may not need.

The other piece of a real workup is checking LH and FSH alongside total testosterone. If T is low and LH/FSH are high, the problem is in the testes (primary hypogonadism). If T is low and LH/FSH are also low, the problem is in the brain signaling (secondary hypogonadism), and the workup should include things like a prolactin level and sometimes brain imaging. These distinctions affect both prognosis and treatment.

The classic symptoms of male hypogonadism overlap heavily with the symptoms of being a stressed, sleep-deprived, undertrained, or depressed man in his 30s or 40s. Low libido. Fatigue. Reduced morning erections. Mood changes. Loss of motivation. Reduced muscle mass and strength. Increased belly fat. Brain fog.

Each of those can be caused by low testosterone. Each can also be caused by chronic sleep debt, untreated sleep apnea, depression, alcohol use disorder, opioid use, anabolic steroid history, severe caloric restriction, overtraining, chronic illness, or several common medications (including some antidepressants, opioids, and finasteride).

That is why a thoughtful clinician does not jump straight from "I am tired and my libido is down" to "let us check your testosterone." A proper history asks about sleep, stress, alcohol, medications, exercise, eating patterns, and mental health first. If those reveal a likely cause, addressing that cause is usually the first move.

When testosterone is then checked and it is genuinely low on two morning draws, that is a meaningful finding. When testosterone is in the low-normal range and symptoms are present, the conversation gets harder — there is no clean line, and reasonable clinicians can disagree about whether a borderline reading warrants a trial of treatment.

There are no supplements with strong evidence for raising testosterone in healthy men. The supplement industry has tried every plant extract you can name; the trials have been mostly negative or weakly positive. Save your money.

What does work, in men with low or low-normal testosterone, are the boring lifestyle interventions:

Sleep. Even one week of restricted sleep (5 hours per night) drops testosterone by about 10–15% in healthy young men. Chronic sleep debt and untreated sleep apnea are among the most common reversible causes of low T.

Resistance training. Compound lifts, performed consistently, raise both acute and baseline testosterone. The effect is modest but real.

Lose visceral fat. Excess abdominal fat is associated with lower testosterone, in part because adipose tissue contains aromatase, an enzyme that converts testosterone to estradiol. Studies of weight loss in men with obesity routinely show testosterone increases of 50–100 ng/dL, sometimes more.

Eat enough. Severe caloric restriction and very low fat intake both suppress testosterone. Athletes who chronically under-fuel often present with low T that resolves with adequate nutrition.

Manage stress. Chronic high cortisol antagonizes testosterone production. This one is harder to translate into a prescription, but addressing the things in your life that are producing chronic high cortisol is usually a good idea regardless.

Doing these things consistently for three to six months and then re-checking testosterone is a reasonable approach for a man with borderline-low levels, mild symptoms, and identifiable lifestyle issues. If T comes up and symptoms improve, you have your answer. If neither moves, the conversation about TRT is more legitimate.

When TRT is appropriate, there are several delivery methods. The choice depends on cost, convenience, side effect tolerance, and patient preference.

Intramuscular injections (testosterone cypionate or enanthate) are the most common. Typical dosing is 100–200 mg once weekly or 50–100 mg twice weekly. Twice-weekly dosing tends to produce smoother levels with fewer mood and energy swings. Self-administered subcutaneous injection (rather than intramuscular) is also widely used and well tolerated.

Topical gels (AndroGel, Testim) are applied daily to the shoulders or upper arms. They produce relatively stable levels but require careful application to avoid transferring testosterone to a partner or child by skin contact.

Pellets are small testosterone implants placed under the skin (usually in the buttocks) by a clinician, lasting three to six months. Pros: no daily routine. Cons: dose cannot be adjusted once placed, and removal is difficult if side effects appear.

Oral testosterone undecanoate (Jatenzo, Tlando) is taken by mouth twice daily. Older oral testosterone formulations were liver-toxic; the modern undecanoate versions bypass first-pass liver metabolism and are safer, though more expensive.

Each delivery method produces broadly similar long-term outcomes when dosed appropriately. The right choice for any individual patient comes down to lifestyle and preference.

TRT is not "set and forget." Once you are on it, you should expect ongoing labs every three to six months, especially in the first year.

Total testosterone (and sometimes free testosterone) is checked to make sure the dose is producing levels in the upper normal range, not above.

Hematocrit and hemoglobin are checked because TRT increases red blood cell production. About 5–10% of men on TRT develop polycythemia (hematocrit >54%), which raises the risk of clotting events. Treatment is usually a dose reduction or a therapeutic phlebotomy.

Estradiol is checked because some testosterone is converted to estradiol via aromatase. Modestly elevated estradiol is normal and not necessarily a problem; significantly elevated levels can cause water retention, mood changes, and gynecomastia.

PSA and a prostate exam are checked yearly. TRT does not cause prostate cancer, but it can accelerate the growth of an existing prostate cancer. Pre-existing prostate cancer is generally a contraindication, and a baseline PSA is essential before starting.

Lipids and metabolic markers are followed because TRT modestly affects HDL cholesterol and can have other metabolic effects.

A clinician who prescribes TRT and then never checks labs is not practicing legitimate care. Ongoing monitoring is part of the contract.

TRT suppresses sperm production. This is one of the most important facts to understand before starting therapy, and it is one of the things that direct-to-consumer testosterone marketing tends to gloss over.

When you take exogenous testosterone, your hypothalamus and pituitary detect the elevated circulating levels and reduce GnRH and LH/FSH output. The testes, deprived of those signals, downregulate both their own testosterone production and their sperm production. For most men, this means sperm count drops dramatically — often to near zero — within a few months of starting TRT.

In some men, sperm production recovers within months of stopping TRT. In others, recovery takes years, or never fully returns to baseline. The longer TRT has been used and the higher the doses, the longer recovery tends to take.

For men who want to preserve fertility, several options exist: sperm banking before starting TRT, using human chorionic gonadotropin (hCG) alongside TRT to keep the testes signaling intact, using clomiphene or enclomiphene (which raise endogenous testosterone production by stimulating the pituitary, rather than replacing testosterone directly), or simply postponing TRT until childbearing is complete.

A clinician who prescribes TRT to a man who has not had children — or who wants more children — without explicitly discussing fertility options is missing a critical conversation. If your prescriber does not bring it up, you should.

TRT is well-studied, effective, and appropriate care for men with documented hypogonadism — confirmed low testosterone on two morning labs plus consistent symptoms — when reversible causes have been addressed and the patient has been informed about the trade-offs.

For these men, TRT can meaningfully improve libido, energy, mood, muscle mass, bone density, and overall quality of life. The trial data on cardiovascular outcomes has been reassuring; older concerns about TRT and heart attack risk have not been borne out in large trials of men with proper diagnoses. The TRAVERSE trial, published in 2023, showed that TRT in middle-aged and older men with low T and high cardiovascular risk did not increase major cardiovascular events compared with placebo.

For men with borderline numbers, vague symptoms, and addressable lifestyle issues, TRT is rarely the right starting move. The right starting move is sleep, training, weight loss, and a careful look at medications — and a re-test in three to six months.

For men who are being marketed TRT through a website that did not check their labs twice, did not check LH/FSH or prolactin, did not screen for sleep apnea or depression, did not discuss fertility, and did not explain monitoring — that is sales, not medicine. The decision to start TRT is one of the more consequential medical decisions a man in his 30s or 40s can make. It deserves a real workup and a real conversation.

For men who do start TRT after a proper workup, the first six months are typically the most informative period. Some changes are noticeable within weeks; others take months to develop. Knowing the realistic timeline helps avoid the common pattern of expecting a transformation in the first month and being disappointed.

Weeks 1–4. Energy, mood, and libido often shift first. Many men describe a return of motivation and interest, and morning erections may become more frequent. Lab levels rise toward target during this period.

Months 1–3. Body composition changes start to become visible if you are also resistance training. Muscle mass and strength tend to increase over this window; body fat may decrease modestly. Sleep quality often improves.

Months 3–6. The longer-term effects on bone density, lipid profile, hematocrit, and cardiovascular markers begin to show up in lab work. This is the period where dose adjustments are most often needed — either to bring testosterone into a tighter target range or to address side effects like polycythemia.

Beyond six months. The picture stabilizes. Ongoing monitoring continues every three to six months in the first year and every six to twelve months after that, depending on your clinician’s judgment and your specific situation. The goal at every check is the same: testosterone in the target range, hematocrit safe, estradiol reasonable, prostate stable, and symptoms improved relative to baseline.