The science of andropause and TRT

What testosterone does

Testosterone is the dominant male sex hormone. It drives libido, erectile function, sperm production, red blood cell production, bone density, muscle mass, mood regulation, energy, and visceral fat distribution.

Men produce peak testosterone in their late teens and twenties. Levels decline by roughly 1 to 2 percent per year from the thirties onwards. This is normal age-related decline. When the decline produces symptoms plus biochemical evidence of hypogonadism, we call it andropause or late-onset hypogonadism.

What the research actually shows

The TRAVERSE trial (2023, 5,200 men with hypogonadism and cardiovascular risk) found TRT did not increase major adverse cardiac events versus placebo over five years. This settled a long-running safety question.

The T-Trials (2016) showed TRT in men over 65 with low testosterone improved sexual function, mood, walking ability, and anaemia. Effects on cognition and fatigue were smaller than patients typically expect.

TRT does not extend life expectancy. TRT does not prevent dementia. TRT does not cure depression. It treats testosterone deficiency.

How we diagnose testosterone deficiency

We require two things together: a validated symptom picture (ADAM questionnaire, sexual symptoms prioritised) AND two morning serum total testosterone measurements below the laboratory reference range, typically under 12 nmol/L with confirmation below 8 nmol/L. Plus exclusion of reversible causes: obesity, sleep apnoea, opioid use, chronic illness, pituitary disease.

Free testosterone and SHBG matter. A man with total T of 11 but high SHBG has less bioavailable testosterone than his total suggests. We calculate free T from total T, SHBG, and albumin.

LH and FSH distinguish primary (testicular) from secondary (pituitary) hypogonadism. Prolactin catches a rare but important prolactinoma.

How we prescribe

First decision: does a reversible cause explain the low testosterone? Weight loss, CPAP for undiagnosed apnoea, or stopping opioids can normalise levels without TRT in a significant minority. We test the reversible options first where appropriate.

Second decision: delivery form. Gels (Testogel, Tostran) are daily, gentle, and easy to stop. Injections (Nebido, Sustanon) are convenient but harder to fine-tune. Patches are rarely used. Pellets are not commonly offered in the UK. We match the delivery form to your life and your preference.

Third decision: dose. We start low and titrate against symptoms, total T, free T, haematocrit, and E2 over the first 12 to 16 weeks.

What we monitor

• Total and free testosterone - aiming for mid-normal range, not supraphysiological

• Haematocrit - TRT raises red cell count, needs monitoring to avoid hyperviscosity

• PSA and digital rectal exam (annually over 45)

• Oestradiol (E2) - aromatisation of T into E2 needs tracking, particularly in heavier patients

• Lipid profile and HbA1c - TRT modestly improves both in hypogonadal men

• Mood, libido, sleep, erectile function - self-reported outcomes are part of the monitoring picture

What TRT does not treat

If your symptoms are fatigue, low mood, and poor sleep but your testosterone is normal, TRT will not help and may cause harm. We screen aggressively for the common competing diagnoses: untreated sleep apnoea, subclinical hypothyroidism, depression, iron deficiency, chronic insomnia, and the cumulative effect of metabolic disease. Treating the right thing matters more than prescribing the fashionable thing.

Why this matters for your treatment plan

Our approach: correct the testosterone if it is genuinely low, monitor the things that matter, screen for competing diagnoses before starting, and share care with your NHS GP where appropriate. TRT is a long-term commitment for most men who start; we make sure starting is the right call.