Testosterone after 40, the honest version

I was forty-one when I asked my GP for a testosterone test, and I asked because I had read three Reddit threads in a row about men in their forties feeling "a bit flat" and getting their levels checked. I felt a bit flat. The threads were persuasive in the way Reddit threads are at midnight when you have had two beers and your sleep tracker says you have averaged six hours fourteen minutes for the last fortnight. I sat across from him and said, with as much casual middle-aged-bloke energy as I could muster, "I just want to rule out low T". He looked at me over the top of his glasses, the way GPs do when they have heard the same sentence eleven times that month, and said, "Sure. We''ll test it. But before we get the result, can I tell you what I think it''s going to say?"

He was right. My testosterone came back in the middle of the reference range, slightly below the average for my age, well above anything that would qualify as deficient. He drew a line on a piece of paper and put my number on it, and then drew the line that would qualify for treatment, and the gap between the two was wide enough to drive a ute through.

This is the honest version of testosterone after forty, and it is going to disappoint you slightly, because most of what the internet tells men our age is either oversold by clinics or undersold by GPs who have stopped listening.

What "low T" actually is, on paper

In Australia, testosterone is measured in nanomoles per litre (nmol/L), and the laboratory reference range for adult men typically sits somewhere between 8 and 27 nmol/L, depending on the lab. That range is enormous. A man at 9 and a man at 26 are both "normal" by the reference, but they will feel like different species.

For a clinical diagnosis of androgen deficiency in Australia (the official term, not "low T"), the Endocrine Society of Australia guidance is roughly:

• Total testosterone consistently below 8 nmol/L on two morning blood tests, taken between 7 and 10am, fasted
• Plus symptoms (low libido, fatigue, loss of morning erections, mood changes, reduced muscle mass)
• Plus an identifiable cause (pituitary problem, testicular problem, genetic condition, certain medications)

That last bit matters in Australia, because the PBS will not subsidise testosterone replacement therapy unless there is a documented organic cause. "Age-related decline" is not a PBS-eligible cause. If your levels are dropping because you are forty-six and you have been forty-six for a while, the public system will not pay for TRT, and your GP cannot prescribe it on the PBS without an endocrinologist confirming the diagnosis.

Total testosterone is also only part of the picture. The clinically useful number is often free testosterone (the bit that is not bound to sex hormone binding globulin and is actually available to your tissues), and free testosterone declines faster than total testosterone with age. A man with a total of 14 and high SHBG can have functionally lower free T than a man with a total of 11 and low SHBG. If you are getting tested and your result comes back ambiguous, ask whether free testosterone or calculated free testosterone was reported. It usually is not, by default.

What the decline actually looks like

Testosterone in men peaks in the late teens and early twenties, plateaus through the late twenties and thirties, and starts declining at roughly 1 to 2 percent per year from around age forty. That is the population average. Some men decline faster, some barely decline at all, and the variation is heavily driven by lifestyle factors that are within your control.

By fifty, the average man has lost something like 15 to 20 percent of his peak testosterone. By sixty, closer to 30 percent. Most of that decline is gradual, and most men adapt to it without noticing, because the symptoms (slightly less energy, slightly less drive, slightly slower recovery) creep in at the speed of a tide coming in. You do not feel it from one day to the next. You feel it when you compare a Sunday at thirty-two to a Sunday at forty-six and realise the same activities cost you more.

The rate of decline is what should worry you, not the decline itself. A man who drops from 18 to 12 nmol/L over fifteen years is doing roughly what biology expects. A man who drops from 18 to 10 over three years has something else going on, and that something else is almost always one of the boring four things below.

The boring stuff that fixes T (mostly)

The single most important thing I can tell you, and the thing the men''s clinic on Instagram will not tell you because it is bad for business, is this. For most men with mid-range or slightly low testosterone, the lever is not pharmaceutical, it is behavioural. The body is a system that responds to inputs, and the inputs that move testosterone are unsexy.

• Sleep (under six hours a night drops testosterone by 10 to 15 percent within a week, in controlled studies)
• Body fat (visceral fat aromatises testosterone into oestrogen, and a 5 percent body weight loss can lift T by 10 to 20 percent)
• Alcohol (chronic intake above ten standard drinks a week measurably suppresses T, and acute binges suppress it for 24 to 48 hours)
• Resistance training (compound lifts, two to three times a week, raise both T and testosterone receptor density)

That is the list. The list is not glamorous. There is no peptide on it, no patch, no clinic. If your sleep is shot and your waist is creeping over 100cm and you are drinking four nights a week and you have not lifted anything heavier than a coffee in two years, your testosterone is doing exactly what it is supposed to do given the inputs you are giving it. Fix the inputs for six months before you fix the hormone.

I know this because I did the inputs. I went from six and a quarter hours of sleep to seven and a half. I cut alcohol from twelve units a week to four. I lost six kilograms over five months. I started doing three lifts a week (squat, deadlift, press, the unsexy compound stuff). At the next blood test, eight months later, my testosterone had moved up by about 25 percent, well into the upper third of the reference range, and I felt like I had been sleeping better, which I had been, because I had been sleeping better. The hormone was downstream.

When to actually see a doctor

If you have done the boring stuff for six months and you still feel flat, then it is reasonable to investigate further. The signs that warrant a proper workup, not a TikTok-driven panic, are:

• Loss of morning erections that persists for months (one of the most reliable signs of genuinely low T)
• Significant unexplained loss of muscle mass or strength
• Persistent low libido that is not explained by relationship dynamics, stress, or SSRIs
• Fatigue that has not responded to sleep, exercise, and reducing alcohol
• Mood changes (irritability, low motivation) that are out of character

The right path is a GP, not a men''s clinic. Ask for a fasted morning total testosterone, SHBG, free testosterone (or calculated free), LH, FSH, and prolactin. Two tests, two different mornings, ideally a few weeks apart. If both come back genuinely low and you have symptoms, your GP will refer you to an endocrinologist. The endocrinologist''s job is to find out why, not just to prescribe. There are causes you would want to find (pituitary tumour, haemochromatosis, undiagnosed type 2 diabetes), and a clinic that hands you testosterone gel after a single phone consult is skipping that step.

The men''s-clinic warning

There is a category of business in Australia, growing fast, that markets directly to men our age via Instagram and YouTube, sells "hormone optimisation" without an endocrinologist on staff, and prescribes testosterone via telehealth after a 15-minute call and a single blood test. Some of these clinics are legitimate operations with proper medical oversight. Many are not. The signs to watch for:

• No endocrinologist involved in your care
• A single consult before prescription, no follow-up monitoring schedule
• Recommending testosterone "for optimisation" rather than treating a diagnosed deficiency
• Pushing combinations (HCG, anastrozole, peptides) on top of testosterone without specific clinical justification
• Cash-only pricing, no Medicare item numbers, no PBS pathway even discussed

Testosterone replacement is not a benign intervention. Once you start, your body downregulates its own production, and coming off is not like stopping caffeine. You may need monitoring of haematocrit, prostate, lipids, and fertility for the rest of your life. The decision to start should be made by someone who understands the long view, not someone whose business model is "monthly subscription to a Schedule 4 hormone".

If you are already on TRT and reading this and feeling defensive, that is fine. There are men who genuinely need it, and modern TRT, well-monitored, is a reasonable medical intervention. The question is whether your prescribing pathway included an endocrinologist, ongoing monitoring, and a real diagnosis. If it did, carry on. If it did not, get a second opinion from an actual specialist, not another telehealth GP.

The body declines. That is true. The decline is mostly slower than you fear. The fix is mostly more boring than you hope. Sleep first, lift second, drink less third, and only then talk about hormones.