I'll tell you how this article started. I was at the gym (which, for context, is not a place where I typically have medical epiphanies) and a mate of mine, mid-thirties like me, said something that stuck with me. He'd been feeling flat for months. Tired. No motivation. Gym sessions going backwards. Libido... not what it used to be. And his conclusion was: "I reckon my testosterone's cooked."
Which. Maybe. But also, maybe not.
He hadn't actually tested. He'd watched some videos online, read a few Reddit threads, and landed on a self-diagnosis that felt right. I think that's common now. Testosterone has become one of those topics where the online conversation has completely outpaced the clinical one. There are entire ecosystems built around the idea that if you're a man over thirty and you're tired, it's probably your testosterone. Podcasts. Influencer accounts. TRT clinics with aggressive marketing.
Sometimes it is. But sometimes it's your iron. Or your thyroid. Or your sleep. Or your stress. Or the fact that you're drinking too much and not eating properly. Or a combination of all of those things.
I'm not dismissing testosterone as a legitimate concern. It absolutely is, and I'll lay out the evidence for why testing matters. But the conversation needs to be rebalanced. The gap between "low T TikTok culture" and what a thoughtful clinician actually considers when a man presents with these symptoms is significant.
This article is my attempt to bridge that gap. What testosterone tests actually measure, who should be testing, how to interpret the numbers, and what the Australian clinical landscape looks like right now.
A note before we get into it
I'm not a doctor. This is general information, not clinical guidance.
Testosterone is one of the most politicised biomarkers in men's health. Strong opinions on all sides. Some clinicians believe it's massively under-diagnosed. Some endocrinologists think prescribing has gone too far. Some men feel dismissed when they raise concerns with their GP. I've tried to present the clinical evidence fairly, while being honest about where the science is settled and where it isn't.
If you have concerns about your testosterone levels, your GP is the right starting point. If you're currently using testosterone (prescribed or otherwise), or you have a pituitary or testicular condition, work with your endocrinologist or specialist.
What testosterone actually does, beyond the headlines
Testosterone is the primary androgen in men. It's produced mostly in the testes, with a small amount from the adrenal glands. It's regulated by a feedback loop involving the hypothalamus and pituitary gland, specifically through luteinising hormone (LH) and follicle-stimulating hormone (FSH).
Its roles are broader than most people realise. Yes, it drives libido and supports erectile function. But it also helps maintain muscle mass and strength, bone mineral density, fat distribution, red blood cell production, mood regulation, and cognitive function.
That's exactly the problem. Symptoms of low testosterone are nonspecific. Fatigue, low mood, reduced motivation, poor concentration, weight gain, muscle loss. These overlap with about fifteen other conditions — depression, thyroid dysfunction, iron deficiency, sleep apnoea, chronic stress, excess alcohol, sedentary lifestyle.
The overlap is the whole problem. You can't diagnose low testosterone from symptoms alone, and you can't assume symptoms are caused by low testosterone just because your level comes back below a threshold. The relationship between a number on a blood test and how you actually feel — it's more complex than most online content suggests.
What the tests measure
When people say "get your testosterone checked," they usually mean total testosterone. But the full picture involves several markers that tell you different things.
Total Testosterone
What it measures
The total amount of testosterone in your blood. That includes the fraction bound to proteins (SHBG and albumin) and the small fraction that's unbound ("free").
Why it matters
Total testosterone is the standard starting point for assessment. Most reference ranges and clinical guidelines are based on total testosterone measured from a morning blood sample.
Normal range in Australia: Typical reference ranges are approximately 9–28 nmol/L, though these vary between laboratories and assay methods. The Endocrine Society of Australia's position statement uses thresholds rather than a single cutoff. Below 6 nmol/L is considered clearly low. Levels between 6 and 15 nmol/L may be clinically relevant depending on symptoms and context.
A note on assay methods: Not all testosterone tests are equal. The standard immunoassay method, used by most labs for routine testing, is adequate for most situations but can be less accurate at very low or very high levels. Liquid chromatography-mass spectrometry (LCMS) is more precise and is preferred when accuracy matters most. For example, when levels are borderline, when monitoring testosterone replacement therapy, or when there's a clinical need for greater precision.
Test it with Bloody Good:
Product: Testosterone Blood Test
LCMS option: Testosterone LCMS Blood Test
Free Testosterone
What it measures
The small fraction of testosterone (roughly 1–3% of total) that isn't bound to any protein and is therefore immediately available for your cells to use.
Why it matters
Total testosterone can look normal while your bioavailable testosterone is actually low. This typically happens because SHBG is elevated and binding up more of the total pool. In these cases, free testosterone gives a more accurate picture of what your tissues are actually working with.
Free testosterone is especially useful in men with borderline total testosterone, older men, and men with conditions that elevate SHBG (liver disease, hyperthyroidism, certain medications).
Test it with Bloody Good:
Product: Testosterone Free/Total + SHBG
SHBG (Sex Hormone-Binding Globulin)
What it measures
The level of the binding protein that carries testosterone in the blood.
How it affects your results
SHBG acts like a transport vehicle. When SHBG is high, more testosterone is bound and less is free. When SHBG is low, more testosterone is unbound. So SHBG levels directly affect how much testosterone is actually bioavailable, even if your total testosterone looks fine.
SHBG tends to increase with age, liver disease, hyperthyroidism, and certain medications (including some anticonvulsants). It tends to decrease with obesity, type 2 diabetes, and hypothyroidism.
This is one of the reasons "just testing total testosterone" sometimes gives an incomplete picture.
Test it with Bloody Good:
Product: Testosterone Free/Total + SHBG
LH and FSH
What they measure
Luteinising hormone (LH) and follicle-stimulating hormone (FSH). These are the pituitary hormones that signal the testes to produce testosterone and sperm.
Why they matter
If testosterone is low, the next question is why. LH and FSH help answer that.
If LH is elevated alongside low testosterone, it suggests the testes aren't responding adequately to pituitary signals. That's primary hypogonadism, a testicular issue. If LH is low or inappropriately normal alongside low testosterone, it suggests the pituitary or hypothalamus isn't sending the right signals. That's secondary hypogonadism, which may be related to obesity, chronic illness, medications, stress, or rarely, a pituitary tumour.
This distinction matters because the cause determines the appropriate response.
The natural decline: what's real and what's exaggerated
Here's where the conversation gets messy.
Testosterone does decline with age. That's not disputed. Most studies estimate a decline of roughly 1–2% per year after age 30, though there's enormous individual variation.
But recent longitudinal research has shown that a big chunk of what we attribute to "age-related testosterone decline" may actually be driven by weight gain, accumulating health problems, medication use, and lifestyle factors. One cross-sectional study of men who remained in excellent health found relatively stable testosterone and LH concentrations well into their seventies and eighties. Age alone doesn't inevitably tank your testosterone.
The Endocrine Society of Australia's position statement puts it clearly: there are no convincing data that healthy ageing necessarily results in testosterone falling to levels that constitute clinical deficiency.
This matters because the online narrative ("you're over 30, your testosterone is declining, you need to do something about it") is a simplification. It conflates normal ageing with pathological deficiency — and they're not the same thing. Treating one as though it's the other leads to a lot of unnecessary anxiety and, in some cases, inappropriate treatment.
That said. If you're genuinely symptomatic — not just "I saw a podcast and now I'm worried" but consistently experiencing reduced libido, erectile dysfunction, unexplained fatigue, loss of motivation, loss of muscle mass, or mood changes, and those symptoms have persisted for months, then testing is completely reasonable. The point isn't to dismiss the concern. It's to investigate properly rather than jumping to a conclusion.
Symptoms that should prompt testing
The Endocrine Society of Australia outlines specific symptoms associated with androgen deficiency. Not all symptoms are equally specific. Some are strongly indicative. Others are suggestive but overlap heavily with other conditions.
More specific symptoms:
Reduced libido (sexual desire). Erectile dysfunction. Breast enlargement (gynaecomastia). Loss of body and facial hair. Very small or shrinking testes. Hot flushes (less common, but can occur). Infertility.
Less specific symptoms (high overlap with other conditions):
Fatigue and low energy. Depressed mood or irritability. Difficulty concentrating. Reduced muscle mass or strength. Increased body fat, especially abdominal. Decreased motivation. Sleep disturbances.
The less specific symptoms are the ones most men present with. On their own, they could be anything. That's why testosterone should be investigated as part of a broader workup, not tested in isolation while ignoring iron, thyroid, blood sugar, sleep, and mental health.
If my mate at the gym had come to me, I'd have said: test your testosterone, sure. But also test your iron, your thyroid, your HbA1c, your vitamin D, and your FBC. If you're only checking one thing, you might find an answer — but you'll probably miss the real one.
Who should get tested
Testing makes sense in the following situations:
Men with specific symptoms of androgen deficiency, especially the more specific symptoms listed above, present for at least several months.
Men with conditions known to affect testosterone, including type 2 diabetes, obesity (especially significant), chronic kidney disease, HIV, chronic opioid use, glucocorticoid therapy, pituitary disorders, Klinefelter syndrome, or a history of testicular injury, surgery, or cancer treatment.
Men considering fertility. Testosterone is part of the broader hormonal picture relevant to sperm production.
Men currently on TRT. Regular monitoring of testosterone levels, plus haematocrit, PSA, and lipids, is standard practice during testosterone replacement therapy.
Men establishing a baseline. Some men around their mid-thirties want a reference point to compare against in the future. This isn't clinically necessary, but it's not unreasonable. Knowing your baseline at 35 makes any future investigation more informative.
Routine population screening is not recommended. Testing "just because" in an asymptomatic man with no risk factors isn't supported by current guidelines. But if you're reading this article, you probably have a reason — and that's enough.
How to get accurate results
Testosterone testing is more sensitive to timing and conditions than most people realise.
Test in the morning. Testosterone follows a circadian rhythm, peaking between about 7am and 10am and declining through the day. Afternoon testing can produce results 20–30% lower than morning levels in the same person. Most reference ranges and clinical guidelines are based on morning samples.
Fast if you can. While fasting isn't strictly required for testosterone, non-fasting blood draws can lower SHBG and affect the results. If you're testing first thing in the morning anyway, fasting overnight makes sense.
Two samples before drawing conclusions. Testosterone fluctuates day to day. A single low result should always be confirmed with a repeat test on a separate day before any clinical decisions are made. This is standard practice, not excessive caution.
Avoid testing when acutely unwell. Illness, injury, poor sleep, extreme stress, and heavy alcohol use can temporarily suppress testosterone. Test when you're relatively stable.
Mention all medications and supplements. Opioids, glucocorticoids, anticonvulsants, and anabolic steroids all affect testosterone levels. So do some over-the-counter supplements. Full disclosure gives cleaner data.
Consider the assay method. Standard immunoassay is fine for most purposes. If your result is borderline or if you're on TRT, ask about LCMS testing for greater accuracy. Bloody Good offers both options.
Understanding your numbers
Total Testosterone reference range (typical Australian lab): ~9–28 nmol/L
But reference ranges aren't the same as clinical thresholds. Here's a more practical framework, drawing from the Endocrine Society of Australia's position statement:
Below 6 nmol/L. Clearly low. If confirmed on repeat testing with consistent symptoms and no reversible cause (like obesity or medication), this typically warrants further investigation and likely discussion about testosterone therapy.
6–15 nmol/L. The grey zone. This is where context matters most. Some men in this range are genuinely symptomatic and may benefit from treatment. Others are in this range because of weight, sleep apnoea, or other reversible factors that should be addressed first. LH and FSH help clarify whether this is a primary testicular issue or secondary to something else.
Above 15 nmol/L. Generally considered adequate. If you're symptomatic with a total testosterone above 15 nmol/L, the cause of your symptoms is more likely something other than testosterone deficiency. That doesn't mean everything's fine — it means the investigation needs to look elsewhere.
Free Testosterone is interpreted alongside total testosterone and SHBG. If your total testosterone is borderline-normal but your free testosterone is low and your SHBG is elevated, that's a different clinical picture than if everything is in range.
A few caveats. Reference ranges vary between labs. Assay methods matter. And numbers without context are just numbers. A result of 11 nmol/L in an otherwise healthy 35-year-old with no symptoms means something different than the same result in a 50-year-old with fatigue, erectile dysfunction, and loss of muscle mass.
The "low T" conversation: what your clinician is actually thinking
When a man presents with fatigue, low libido, and a testosterone level of 10 nmol/L, here's the clinical thought process:
"Is this result accurate?" Was it a morning sample? Was the man fasting? Was he unwell? On medications? This needs to be confirmed with a second test.
"Is there a reversible cause?" Obesity is one of the most common contributors to secondary testosterone suppression. Sleep apnoea is another. Depression, chronic stress, opioid use, excessive alcohol — all can suppress testosterone without there being any pathology in the testes or pituitary. The Endocrine Society of Australia's position statement specifically notes that testosterone therapy is not appropriate when the low level is attributable to these reversible factors.
"Is this primary or secondary?" LH and FSH tell the story. Elevated LH = the pituitary is shouting at the testes and they're not responding. Low or normal LH with low testosterone = the pituitary isn't sending the signal, which raises different questions.
"Are there other things contributing to the symptoms?" A man with a testosterone of 10, a ferritin of 22, a vitamin D of 35, poor sleep quality, and a BMI of 32 has multiple factors at play. Treating the testosterone alone is unlikely to fix how he feels.
"Does this man need TRT, or does he need lifestyle medicine?" This is the honest question that doesn't get asked enough online. In many cases (not all, but many), optimising sleep, managing weight, improving nutrition, reducing alcohol, and treating any underlying conditions can raise testosterone levels without pharmaceutical intervention.
None of this means TRT is inappropriate. For men with genuine hypogonadism, where a pathological deficiency is confirmed by testing and clinical assessment, testosterone therapy can be transformative. But the pathway to that decision is more nuanced than "my level is 10, give me testosterone."
What happens after a low result
If your level is confirmed low on repeat testing:
Your GP will likely refer you to an endocrinologist, or investigate further themselves. The workup may include LH, FSH, prolactin, thyroid function, iron studies, cortisol, and sometimes pituitary imaging (MRI), depending on the clinical picture.
If the cause is reversible:
Address the underlying factor first. Weight loss, treatment of sleep apnoea, improving sleep quality, reducing alcohol, cessation of opioids where clinically appropriate, managing stress — these are all legitimate first-line interventions. Retest after 3–6 months of sustained change.
If TRT is indicated:
In Australia, testosterone is a Schedule 4 (prescription-only) medication nationally, with additional restrictions in some states. It's Schedule 1 in Queensland and NSW for possession without a prescription. PBS-subsidised testosterone requires specific criteria to be met. The Australian government tightened prescribing criteria in 2015 — a response to a sharp increase in prescriptions.
TRT requires ongoing monitoring: testosterone levels, haematocrit (testosterone stimulates red blood cell production), PSA (prostate-specific antigen), lipids, and assessment of symptoms and side effects. It's not a set-and-forget intervention.
If your level is in the grey zone:
This is the hardest space. You don't clearly qualify for treatment, but you don't feel right either. The best approach is to address every modifiable factor — body composition, sleep, nutrition, stress, other biomarkers. Then retest. If testosterone remains low despite optimisation, that's a stronger clinical case for further investigation.
Tests to consider through Bloody Good
Core testosterone assessment:
Testosterone Blood Test. Total testosterone via standard immunoassay.
Testosterone Free/Total + SHBG. Total testosterone, free testosterone, SHBG, and Free Androgen Index. A more complete picture, especially if you suspect SHBG may be influencing your result.
Testosterone LCMS Blood Test. Gold-standard accuracy. Worth considering if results are borderline or if you're monitoring TRT.
Related tests to investigate alongside testosterone:
Full Blood Count (FBC). Haemoglobin and haematocrit, relevant both for fatigue investigation and TRT monitoring.
Iron Studies (Including Ferritin). Iron deficiency can cause similar fatigue symptoms.
Thyroid Function Test (TFT). Thyroid dysfunction overlaps heavily with low T symptoms.
HbA1c. Metabolic health and blood sugar regulation.
Vitamin D (25-OH). Commonly low in men with fatigue.
Cortisol Blood Test. Stress hormone, relevant if fatigue and mood are dominant symptoms.
If you want the full picture in one go:
The Performance Check covers 50+ biomarkers geared toward performance and energy, including testosterone, thyroid, iron, cholesterol, liver function, and more. Designed for men who want a targeted health check without ordering ten separate tests.
Or for the broadest baseline: The Bloody Good Test covers 100 biomarkers including everything above plus kidney function, inflammation, and metabolic markers.
When to retest
After a first low result: Always confirm with a second morning sample on a different day. A single low result is not a diagnosis.
After lifestyle changes: If you've addressed modifiable factors like weight loss, improved sleep, reduced alcohol, and better nutrition, retest after 3–6 months to see whether testosterone has responded.
On TRT: Your clinician will typically monitor testosterone, haematocrit, PSA, and lipids at 3 months, 6 months, and then annually.
As a baseline habit: If you tested in your mid-thirties and results were normal, retesting every few years (or if symptoms develop) gives you a meaningful comparison point.
If symptoms change: New onset of symptoms, especially the more specific ones like erectile dysfunction, loss of libido, or breast tissue changes, warrants retesting regardless of previous results.
Explore more biomarkers
If you want to go deeper into any of the markers covered here, the Bloody Good biomarker directory has detailed pages on what each test measures and how to think about your results in general terms.
Browse the Bloody Good Biomarker Directory
This article provides general health information only and is not intended as medical advice, diagnosis, or treatment. Blood test results should be interpreted by a qualified healthcare professional in the context of your individual health circumstances, including symptoms, medical history, and medications. If you are experiencing persistent or concerning symptoms, consult your GP or seek medical attention promptly.