One of the biggest fears men have about TRT is: "Will it increase my risk of heart attack or stroke?"
It's a legitimate concern. And for years, the answer seemed to be yes. Then the evidence shifted.
Let me walk through the evolution of this question and what men on TRT (or considering it) should actually monitor.
The 2010 Basaria Study: The Scare
In 2010, Basaria and colleagues published a study in the New England Journal of Medicine that shook the andrology world. They gave testosterone or placebo to men with limited mobility and low testosterone. The testosterone group had more cardiovascular events.
The headlines screamed: "TRT Increases Heart Attack Risk."
Men considering TRT panicked. Endocrinologists became cautious. The study became the foundation of warnings about TRT and cardiovascular risk.
The problem: the study had significant limitations. Small sample size. Participants had pre-existing cardiovascular disease and mobility impairment. Short follow-up. And crucially, the testosterone doses used were often above physiological replacement.
But the fear stuck. For over a decade, TRT carried a cardiovascular risk stigma.
The 2023 TRAVERSE Trial: The Reassurance
In 2023, the TRAVERSE trial (Testosterone Replacement and Cardiovascular Outcomes in Men) published their results. This was a large, long-term study specifically designed to answer the question: does TRT increase cardiovascular risk?
The population: over 5,000 men with low testosterone and either pre-existing cardiovascular disease or multiple cardiovascular risk factors. The highest-risk men, basically.
The result: no significant increase in major adverse cardiovascular events (MACE) in the testosterone group compared to placebo over 4+ years of follow-up.
This was a major finding. It suggested that in a high-risk population, TRT at physiological doses didn't increase MACE risk.
The caveats:
- There was a trend (not statistically significant) toward more strokes in the TRT group
- The doses used were moderate (maintained total T at 500–800 ng/dL, typical for TRT)
- Individual risk still varies. Some men might be at higher risk than others
But the headline: TRT at physiological replacement doses doesn't appear to substantially increase cardiovascular events in high-risk men. That's a meaningful reassurance.
What TRT Does to Your Cardiovascular System
Blood pressure: TRT slightly increases blood pressure in some men (typically 2–5 mmHg systolic). This is modest and usually manageable with lifestyle or antihypertensives if needed.
Haematocrit: This is the biggest issue. TRT increases red blood cell mass, raising haematocrit (the proportion of blood that's red cells) by 3–5% in most men. A man starting with haematocrit of 42% might reach 45–47%.
Why does this matter? High haematocrit increases blood viscosity, which slightly increases thrombotic (clotting) risk. At haematocrit 55%+, this risk becomes meaningful.
Lipid profile: TRT can slightly lower HDL (good cholesterol) and raise triglycerides in some men, though effects are usually modest with physiological doses.
Vascular function: Paradoxically, TRT often improves endothelial function and vascular health, at least in men who were previously testosterone-deficient.
Haematocrit Management: The Critical Point
If you're on TRT, haematocrit management is your primary cardiovascular concern.
Baseline: Get a haematocrit (or full blood count) before starting TRT.
During TRT: Check haematocrit at 6 weeks, 12 weeks, then every 3–6 months. Most stabilise by 6–12 weeks on a stable dose.
Target: Keep haematocrit below 54%. If it rises above this, action is needed.
If haematocrit is elevated:
- First, recheck it (sometimes there's measurement error)
- Reduce TRT dose slightly
- Increase hydration
- Donate blood (1 unit = ~500mL) every 2–3 months
- Consider therapeutic phlebotomy with a doctor's guidance
Most men stay in the healthy range with proper monitoring and dose management. A small proportion (5–10%) have naturally high haematocrit tendencies and need careful management or may not be suitable for TRT.
Blood Pressure Monitoring
Baseline: Check blood pressure before starting TRT. Ideally a series of readings over a week (home BP monitoring is most accurate).
During TRT: Recheck at 6 weeks, then every 3–6 months.
If BP rises: Often small increases (2–5 mmHg) don't require intervention. If it rises significantly (>10 mmHg systolic), adjust TRT dose or consider adding antihypertensive medication if you're already on one.
Most men don't see clinically significant BP increases on physiological TRT doses. But some do, and monitoring catches it early.
Lipid Profile
Baseline: Fasting lipid panel before TRT.
During TRT: Recheck at 6 weeks, 12 weeks, then every 6–12 months.
TRT effects on lipids are usually modest with physiological doses. Some men see a slight HDL decrease (2–5%), others see minimal change. Triglyceride effects are variable.
If lipids deteriorate significantly, discuss with your doctor: dose adjustment, lifestyle changes (exercise, diet), or statin therapy.
Who Should Be Cautious About TRT?
- Untreated sleep apnoea. TRT can worsen it, and sleep apnoea increases cardiovascular risk. Treat sleep apnoea first.
- Uncontrolled hypertension. Get BP controlled before TRT.
- Severe untreated hyperlipidemia. Manage this first.
- Recent cardiovascular event. Usually TRT is safe after you've stabilised, but discuss with your cardiologist.
- Polycythaemia vera or significant baseline haematocrit elevation (>50%) TRT may not be suitable.
These aren't absolute contraindications, but they require careful risk-benefit assessment with an endocrinologist.
A Practical Monitoring Schedule for Men on TRT
Before starting:
- Full blood count (FBC) — baseline haematocrit, haemoglobin
- Fasting lipid panel
- Blood pressure (multiple readings)
- Consider an ECG if you're over 50 or have significant cardiovascular risk
At 6 weeks:
- FBC (haematocrit, haemoglobin)
- Blood pressure
- Symptoms check
At 12 weeks:
- FBC
- Fasting lipid panel
- Blood pressure
- Full hormone panel (testosterone, LH, FSH, oestradiol)
Every 3–6 months thereafter:
- FBC
- Blood pressure
- Symptoms
Every 6–12 months:
- Full hormone panel
- Lipid panel
- Liver and kidney function tests
This is the standard monitoring. Some private clinics do it more frequently; some less. The key is consistency and acting on findings.
The Honest Assessment
The cardiovascular concern around TRT is not baseless, but it's also not the death sentence some feared. The TRAVERSE trial suggests that at physiological replacement doses, TRT doesn't substantially increase MACE risk in high-risk men.
But this doesn't mean zero risk. Individual variation exists. And it requires careful monitoring.
The men who do well on TRT are those who:
- Monitor haematocrit regularly
- Control blood pressure
- Maintain reasonable fitness and diet
- Don't exceed physiological replacement doses (usually <200 mg/week intramuscular)
- Have regular bloodwork
The men who run into trouble are those who:
- Don't monitor haematocrit and let it drift to 55%+
- Combine TRT with other risk factors (smoking, obesity, poor diet) without addressing them
- Use supraphysiological doses (300+ mg/week, which is abuse, not replacement)
- Skip follow-up appointments
The Bottom Line
TRT at physiological replacement doses doesn't appear to substantially increase cardiovascular events based on the most recent large-scale evidence. But cardiovascular monitoring is essential, especially haematocrit.
If you're considering TRT, understand that it requires ongoing monitoring and commitment. But if you're a candidate and you monitor properly, the cardiovascular risk is manageable and likely lower than previously believed.
Get tested. Understand your baseline cardiovascular health. If TRT is appropriate, commit to regular monitoring. Haematocrit is your most actionable concern. Manage it, and you've addressed the primary cardiovascular risk of TRT.
The evidence is evolving, and the conversation is moving away from "TRT is dangerous" toward "TRT is safe if monitored properly." That's good news for men who genuinely benefit from it.