Testosterone is the cornerstone of male physiology — but its influence extends equally to women, where it regulates libido, bone density, and muscle tone. Whether you're investigating fatigue, weight gain, or declining motivation, understanding your testosterone levels is often the first diagnostic step that gets overlooked.
What Is a Healthy Testosterone Range?
For men, total testosterone is typically measured between 10–35 nmol/L. However, "normal" doesn't mean "optimal" — many men with levels in the 10–15 nmol/L range experience significant symptoms that resolve once levels are optimised. For women, the range is much lower (0.5–2.5 nmol/L) but equally impactful on wellbeing.
Why Testosterone Declines
- Natural ageing — approximately 1–2% decline per year after age 30
- Chronic stress and elevated cortisol — directly suppresses testosterone production
- Poor sleep — most testosterone is produced during REM sleep cycles
- Excess body fat — adipose tissue converts testosterone to oestrogen via aromatase
- Nutritional deficiencies — zinc, vitamin D, and magnesium are all required for synthesis
- Overtraining without adequate recovery
Total vs Free Testosterone
Most testosterone in the bloodstream is bound to Sex Hormone Binding Globulin (SHBG) and is biologically inactive. Only free testosterone — roughly 2–3% of total — is available to tissues. It's possible to have normal total testosterone but low free testosterone and still experience all symptoms of deficiency. A complete panel should measure both.
What Symptoms Should Prompt Testing?
Persistent fatigue, reduced libido, difficulty building or maintaining muscle despite training, increased abdominal fat, mood changes, poor concentration, or sleep disturbances are all signals worth investigating. A simple blood test can clarify whether testosterone is part of the picture.
