Testosterone Replacement Therapy and Cardiovascular Health: Part 2: Optimised, Not Maximised
In Part 1, we looked at how testosterone can influence heart health indirectly through body composition, visceral fat, insulin sensitivity, lean mass, anaemia and exercise capacity.
For men with genuine testosterone deficiency, restoring testosterone to a healthy physiological range may improve several cardiovascular risk markers. But there's an equally important question we haven't answered yet:
Is TRT actually safe for your heart?
It's been one of the most debated questions in men's health for well over a decade, and understandably so.
The good news is that modern evidence is reassuring. Appropriately prescribed TRT in men with confirmed hypogonadism doesn't appear to increase major adverse cardiovascular events, according to the best modern safety trial we have. That said, TRT can still raise blood pressure, increase haematocrit, worsen untreated sleep apnoea, and carry certain risks in men who are poorly selected, poorly dosed or poorly monitored.
As with everything in this series, the principle stays the same:
Optimised, not maximised.
What About Heart Attacks and Strokes?
For years, the biggest concern around TRT was whether it raised the risk of heart attack, stroke or cardiovascular death.
The most important modern trial here is TRAVERSE, published in the New England Journal of Medicine in 2023.
TRAVERSE studied 5,246 men aged 45–80 with symptoms of hypogonadism, two fasting testosterone levels below 300 ng/dL, and either pre-existing cardiovascular disease or high cardiovascular risk. Participants received either testosterone gel or a placebo.
The primary cardiovascular endpoint occurred in 182 men receiving testosterone (7.0%), compared with 190 men receiving placebo (7.3%). The hazard ratio was 0.96, with a 95% confidence interval of 0.78–1.17.
What this means in English is TRT did not increase major adverse cardiovascular events compared with placebo in this carefully selected, closely monitored group of men with confirmed low testosterone.
It doesn't prove TRT prevents cardiovascular events. But it does strongly challenge the old assumption that appropriately prescribed TRT automatically raises your risk of heart attack or stroke.
When it comes to the effect on blood pressure however, TRT still requires blood-pressure monitoring and careful risk assessment.
The Risks: When Testosterone Isn't "Optimised"
The potential cardiovascular benefit of TRT depends entirely on staying within physiological range.
Problems tend to show up when testosterone is prescribed without a clear diagnosis, dosed too aggressively, or pushed beyond what's normal. The main things to watch for include:
raised haematocrit
increased blood pressure
fluid retention
worsening untreated sleep apnoea
possible increased risk of atrial fibrillation
possible increased risk of pulmonary embolism
suppression of fertility
acne, hair loss or mood changes
inappropriate use in men with prostate cancer risk or poor monitoring
TRAVERSE was reassuring on major cardiovascular events, but it also found higher rates of atrial fibrillation, acute kidney injury and pulmonary embolism in the testosterone group, so this isn't a treatment to take lightly.
Atrial fibrillation is worth flagging in particular. A 2024 analysis in older men found that testosterone concentrations in the high-normal range were independently associated with a higher risk of incident atrial fibrillation. Men in the fourth and fifth testosterone quintiles had roughly double the risk compared with men sitting in the middle quintile.
This doesn't mean everyone on TRT is at high risk of atrial fibrillation. What it does mean is that "more is better" is the wrong mindset to bring to this treatment.
Blood Pressure and Haematocrit Matter
Two of the most important safety markers we track during TRT are blood pressure and haematocrit.
Testosterone can stimulate red blood cell production. In men with anaemia, this can be genuinely beneficial. But if red blood cell production rises too far, haematocrit can climb too — and haematocrit is simply the percentage of your blood volume made up of red blood cells. If it gets too high, blood becomes more viscous, which can raise concerns around clotting and cardiovascular strain.
Blood pressure matters just as much. Some men experience fluid retention or a rise in blood pressure on testosterone therapy. That doesn't mean TRT is unsafe across the board, but it does mean treatment needs to be properly monitored, particularly if you already have hypertension or existing cardiovascular risk.
Good TRT was never about prescribing testosterone and hoping for the best. It's diagnosis, dosing, review and ongoing monitoring. Every step of the way.
Who Might Benefit Most?
TRT is most likely to help you if you have:
symptoms consistent with testosterone deficiency
repeatedly low morning testosterone
low free testosterone
an identifiable cause or clear clinical picture
low libido, erectile dysfunction or reduced morning erections
reduced muscle mass or strength
fatigue that isn't explained by anything else
anaemia
low bone density
central obesity or metabolic syndrome alongside confirmed deficiency
a poor response to lifestyle change, despite genuinely sticking with it
That's a very different profile to a man with normal testosterone who simply wants more energy, more muscle or faster fat loss.
In the right patient, TRT can meaningfully improve quality of life and cardiovascular risk markers. In the wrong patient, it can add risk without ever addressing the real problem.
Who Should Be Cautious?
TRT isn't right for everyone, and we'll always be upfront with you about that.
The Endocrine Society recommends against starting testosterone in men planning fertility in the near term, those with elevated haematocrit, untreated severe obstructive sleep apnoea, uncontrolled heart failure, a recent heart attack or stroke within the previous six months, thrombophilia, or certain prostate-related risks without proper assessment first.
This matters because so many of the symptoms linked to low testosterone are non-specific. Fatigue, low mood, poor motivation, weight gain and reduced libido can all be caused by plenty of other things, including:
poor sleep
depression or anxiety
alcohol
stress
shift work
obesity
under-eating
overtraining
medication side effects
thyroid disease
diabetes
relationship factors
A low testosterone result should never be read in isolation. We'll always assess it alongside your symptoms, repeat morning blood tests, free testosterone, SHBG where relevant, your medical history and your lifestyle.
Fertility: A Crucial Point
One of the most commonly overlooked risks of TRT is fertility suppression. It is something we make sure every patient understands before starting treatment.
External testosterone can reduce the brain's signal to the testes, suppressing luteinising hormone and follicle-stimulating hormone. These are the two hormones needed for sperm production. As a result, TRT can significantly reduce fertility.
Every consultation will involve discussing fertility with the patient and allowing the patient to make an informed decision.
Lifestyle Still Comes First
Even when TRT is the right call, it should always sit within a wider strategy for your heart health.
Improving cardiovascular fitness should always still include:
resistance training
aerobic fitness
weight management
blood-pressure control
sleep optimisation
reduced alcohol intake
smoking cessation
adequate protein
fibre-rich nutrition
lipid management
glucose control
In fact, the best results are seen when TRT simply enables you to execute these habits better. A man with genuine testosterone deficiency may struggle to train, recover, maintain muscle or manage his body composition. Correcting his testosterone can give him the physiological platform to actually engage with exercise and nutrition properly.
But TRT without lifestyle change is an incomplete intervention. If you start testosterone but keep sleeping poorly, drinking heavily, avoiding exercise and gaining visceral fat, the deeper cardiovascular problem is still sitting there, unresolved.
Monitoring Is Non-Negotiable
Safe, appropriate TRT means diagnosis, careful dose adjustment and ongoing monitoring.
At Orion Medica, this typically means tracking:
total testosterone
free testosterone or SHBG, where relevant
full blood count and haematocrit
blood pressure
lipids
liver and kidney markers, where appropriate
HbA1c or fasting glucose
PSA and prostate symptoms in appropriate age groups
sleep apnoea risk
fertility intentions
how your symptoms are actually responding
Monitoring matters because the goal was never simply to raise a number on a blood test. It's to improve your symptoms, your health markers and your quality of life, all while keeping testosterone safely within a healthy physiological range.
If your symptoms improve but haematocrit rises excessively, blood pressure creeps up, or sleep apnoea worsens, that's our cue to reassess the plan, not push on regardless.
Optimised, Not Maximised
You'll often hear TRT described as giving you "the testosterone of a 20–30-year-old." It's a useful phrase, but only if it's understood correctly.
It shouldn't mean pushing levels to the very top of the range. It shouldn't mean anabolic-steroid-style dosing. And it should never mean ignoring blood pressure, haematocrit, fertility or your cardiovascular history.
A more responsible way to think about it is this:
Restoring a genuinely deficient man to a healthy physiological range associated with good function — while monitoring carefully and addressing the wider picture of his health.
That's a very different approach to simply chasing high testosterone. There's a significant difference between medical replacement and enhancement. Replacement aims to correct a genuine deficiency. Enhancement aims to exceed normal physiology.
The Bottom Line
TRT may improve cardiovascular health indirectly in men with genuine testosterone deficiency, by improving body composition, reducing visceral fat, supporting lean mass, improving anaemia, enhancing exercise capacity and potentially improving insulin sensitivity.
The strongest modern safety evidence we have suggests that appropriately prescribed TRT does not increase major adverse cardiovascular events in men with confirmed hypogonadism and elevated cardiovascular risk.
But we'd never present TRT to you as a cardiovascular drug, a longevity shortcut, or a way to simply "be 25 again."
The aim isn't to maximise your testosterone. The aim is to restore genuinely deficient men to a healthy physiological range, while improving the broader foundations of cardiovascular health: muscle, fitness, body composition, blood pressure, glucose control, sleep and lifestyle.
Used well, TRT can be part of a genuinely powerful health optimisation strategy. Used poorly, it becomes just another example of mistaking more for better.
At Orion Medica, we're here to help you get this right → with proper diagnosis, careful monitoring, and a plan built around you.
