Testosterone is the primary male sex hormone — but it plays a far broader role than reproduction. It influences energy, mood, bone density, muscle mass, libido, and cognitive function. When levels decline, the effects ripple through your entire wellbeing.
What Is a Normal Testosterone Level?
Total testosterone in men is typically measured in nmol/L. The reference range varies by lab, but generally:
- Normal: 10–35 nmol/L
- Low-normal: 8–12 nmol/L (symptoms may still be present)
- Low (hypogonadism): below 8 nmol/L
Age matters: testosterone peaks in the early 20s and declines by roughly 1–2% per year after 30. By 50, many men have significantly lower levels than they did at 25 — even within the "normal" range.
Symptoms of Low Testosterone
- Persistent fatigue and low energy
- Reduced muscle mass and strength despite training
- Increased body fat, especially around the abdomen
- Low libido
- Mood changes — irritability, low motivation, depression
- Brain fog and difficulty concentrating
- Poor sleep quality
Free vs Total Testosterone
Most of the testosterone in your blood is bound to proteins (mainly SHBG) and is biologically inactive. Only the "free" fraction (roughly 2–3%) is available to your cells. Measuring both total and free testosterone gives a more complete picture — you can have normal total testosterone but low free testosterone and still experience all the symptoms of deficiency.
