TRT Risks and the Monitoring That Should Come With It

Monitoring is not an optional extra bolted onto testosterone treatment. It is the part that makes the treatment safe, and a provider who does not run one is selling you a hormone rather than managing your care.

Testosterone is a Schedule III controlled substance. Prescribing it, refilling it and monitoring it are governed by federal and state rules, and the monitoring requirement is not merely regulatory box-ticking — it exists because the predictable effects of this drug are detectable on blood tests long before they are detectable in how you feel.

Erythrocytosis: the effect that comes up most

Testosterone stimulates erythropoiesis. Red cell mass rises, which shows up as an increasing haematocrit and haemoglobin. In a proportion of men on treatment this rise crosses a threshold where clinicians become concerned, and it is the single most frequent reason for dose reduction, a change of preparation, or stopping.

The concern is that thickened blood may increase the risk of thrombotic events. The strength of that association is debated, but the response is not: haematocrit is measured at baseline, rechecked after starting, and monitored on an ongoing basis. If it climbs above the acceptable range, the options are reducing the dose, switching from injections to a transdermal preparation — which tends to produce a smaller rise — spacing injections differently, addressing contributing factors such as smoking or untreated sleep apnoea, or stopping. Therapeutic phlebotomy is sometimes used but is not a licence to continue at a dose that keeps pushing the number up.

You cannot feel your haematocrit. That is precisely why it is measured.

Obstructive sleep apnoea

Testosterone may worsen existing obstructive sleep apnoea. It is also a condition that commonly coexists with low testosterone and that independently produces fatigue, low libido, low mood and poor concentration — the exact presentation that brings men to hormone clinics.

The sequence that goes wrong looks like this. A man with untreated apnoea has genuinely low measured testosterone, partly because of the apnoea. He is started on testosterone. The apnoea is not identified, may be aggravated, and the symptoms that were always the apnoea's doing persist or worsen — at which point the dose is often increased rather than the diagnosis revisited.

Any competent assessment screens for apnoea before starting. Snoring, witnessed breathing pauses, waking unrefreshed, morning headaches and daytime sleepiness all warrant a sleep study rather than a higher dose. Our article on the overlap between low testosterone symptoms and other conditions covers this in more detail.

Prostate considerations

The older belief that testosterone causes prostate cancer has not been supported by the evidence as it has accumulated. What remains true is more nuanced and still matters.

Testosterone can stimulate growth of prostate tissue that is already present, including cancerous tissue. It is therefore not started in a man with untreated prostate cancer, and it is not started while an unexplained PSA elevation or abnormal examination is outstanding. Baseline PSA is measured in men of an age where prostate assessment is appropriate — that discussion typically begins somewhere in the forties depending on family history and other risk factors — and repeated during treatment. A significant rise, or a new abnormality on examination, triggers urological assessment rather than reassurance.

Men with significant lower urinary tract symptoms are assessed carefully before starting, because those symptoms can worsen. Our guide to testosterone blood testing sets out which baseline measurements belong in the initial workup.

Cardiovascular risk: what is actually known

This deserves a straight answer, and the straight answer is that the picture is not settled.

Over the past fifteen years the evidence has moved in both directions. Some observational studies and a small trial raised concern about cardiovascular events, prompting regulatory labelling changes and a great deal of coverage. Other observational work pointed the opposite way. More recently, a large randomised safety trial in men with hypogonadism and elevated cardiovascular risk was designed specifically to address the question, and its primary findings did not demonstrate an increase in major adverse cardiovascular events — while raising other observations, including on cardiac rhythm and thromboembolism, that continue to be discussed.

What that means in practice. There is no basis for telling patients that testosterone is proven to be cardiovascular-safe, and no basis for telling them it is proven to be dangerous. There is a basis for saying that the men studied were men with diagnosed hypogonadism, and that findings in that group say nothing about men with normal levels taking testosterone for other reasons. Anyone quoting this literature as a settled conclusion in either direction is overstating it.

What follows clinically is unglamorous and evidence-based: manage blood pressure, lipids, glucose, weight and smoking, because those are the things with unambiguous effects on cardiovascular risk. Testosterone does not substitute for any of them.

The rest of the risk picture

Fertility

Exogenous testosterone suppresses the hypothalamic-pituitary-gonadal axis and substantially reduces or stops sperm production in most men. Recovery after stopping is usual but variable and not guaranteed. This is the consequence men most often learn about too late, and it has its own article: TRT and fertility. If there is any chance you will want children, read it before you start.

Skin, breast tissue and mood

Acne and oily skin are common early. Gynaecomastia can develop because some testosterone is converted to oestradiol; this is dose-related and worth reporting rather than tolerating. Mood effects run in both directions — some men feel steadier, others report irritability, agitation or a shorter fuse, and partners sometimes notice before the patient does. Supraphysiological levels are more likely to produce this, which is one reason dosing aims for a normal range rather than the top of it.

Injection-site and preparation-specific issues

Intramuscular and subcutaneous injections can cause local pain, swelling, bruising and occasionally infection if technique or sterility is poor. Transdermal gels carry a genuine risk of transferring testosterone to a partner or child through skin contact — this requires proper application, covering the site, and hand washing, and it is not a theoretical concern. Different preparations produce different peaks and troughs, which affects both symptoms and haematocrit.

Fluid retention and other effects

Some men experience fluid retention, which matters more in those with heart or kidney disease. Testicular shrinkage is expected and reflects the suppression described above. Sleep quality changes are reported both ways.

What a responsible follow-up schedule looks like

Specific intervals vary with the preparation used, the individual, and the guideline a practice follows. The structure, however, is consistent.

Before starting. Confirmed low testosterone on repeat morning samples with matching symptoms. Full blood count including haematocrit. PSA and prostate examination where age-appropriate. Blood pressure, lipids, metabolic screening. Sleep apnoea screening. Fertility discussion. Documented consent that covers the risks above.

The first few months. Review within the first several weeks to months, with repeat testosterone timed appropriately for the preparation, repeat haematocrit, and a symptom review. This is where dose is adjusted, and where a lack of symptom response prompts the question of whether the diagnosis was right rather than whether the dose should be higher.

Around the first year. Repeat testosterone, haematocrit, PSA where applicable, blood pressure and metabolic markers. Reassessment of whether treatment is actually delivering benefit.

Ongoing. Regular scheduled bloods and review at least annually thereafter, more often if anything is unstable, with a standing agreement about what happens if haematocrit rises or PSA changes.

And a genuine exit conversation. If treatment is not producing meaningful benefit, stopping is the correct answer. A practice that never stops anyone is not evaluating anything.

Judging a provider by the monitoring

The monitoring schedule tells you more about a hormone service than its marketing does. Ask what bloods are included, at what intervals, whether they are included in the fee or billed separately, who reviews the results, how you are contacted about them, and what specifically would cause them to reduce or stop your treatment. A service that cannot answer the last question has not thought about it.

Remote care handles this well when it is structured properly and badly when it is not — the boundaries are covered in what telehealth is actually good for. The full picture of who this treatment helps sits in our guide to testosterone replacement therapy, and our hormone health service page describes how assessment and follow-up work here.