Testosterone (total)
Also reported as: Total testosterone · Serum testosterone
Total circulating testosterone, most of which is bound to SHBG and albumin and therefore unavailable to tissue. Ranges here are for men; female physiology sits an order of magnitude lower and needs different interpretation entirely.
For adult men. The 300 ng/dL lower bound is a diagnostic threshold rather than a target, and requires two separate morning samples.
Symptom burden and body-composition outcomes are generally better in the upper half of the range. Above roughly 1,000 in an untreated man, investigate rather than celebrate.
Guideline thresholds from: Endocrine Society clinical practice guideline for testosterone therapy in men
To convert to nmol/L, multiply by 0.0347.
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Where the thresholds sit
| Band | Range (ng/dL) | Note |
|---|---|---|
| Low | < 300 | Confirm with a second morning sample before any conclusion. |
| Below optimal | 300–500 | — |
| Optimal | 500–800 | — |
| High-normal | 800–1000 | — |
| High | > 1000 | In an untreated man this warrants investigation. |
Why it matters
Low testosterone in men tracks with reduced muscle mass, bone density, libido, mood and insulin sensitivity, and with higher all-cause mortality in cohort studies. The honest complication is direction of causation: obesity, poor sleep and chronic illness all lower testosterone, so a low reading is frequently a consequence of something else rather than the thing to treat.
What raises it
- Resistance training and adequate sleep
- Losing visceral fat — adipose tissue converts testosterone to oestradiol
- Correcting vitamin D or zinc deficiency, if genuinely deficient
- Exogenous testosterone, which also shuts down your own production
What lowers it
- Obesity, the single largest modifiable cause
- Short or poor-quality sleep — measurable within a week
- Chronic stress and elevated cortisol
- Opioids, glucocorticoids and some antidepressants
- Excessive endurance training without adequate fuelling
- Ageing, at roughly 1% per year after 30
How to move it
- 1Test properly first: morning, fasted, between 7 and 10am, and twice. Testosterone follows a strong diurnal rhythm and a single afternoon sample is close to meaningless.
- 2Ask for SHBG and free testosterone alongside total. A normal total with high SHBG can still leave you functionally low.
- 3Fix sleep and visceral fat before considering anything pharmacological. Both move the number substantially and neither shuts down your own production.
- 4Resistance training, consistently.
- 5If it is genuinely and persistently low with symptoms, that is a conversation with an endocrinologist — testosterone therapy is a lifelong commitment that suppresses fertility.
What moves this marker
Interventions on this site with evidence behind them for this specific marker. None of them replaces working out why yours is where it is.
What makes a single reading misleading
- Diurnal variation is large — the same man can differ by 20-25% between morning and afternoon.
- Acute illness, recent hard exercise and a poor night's sleep all suppress it temporarily.
- Total testosterone alone can mislead when SHBG is high or low; free testosterone is the better guide in those cases.
- These ranges are for men. Female reference ranges are entirely different and are not covered here.
Sources
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Educational only. Reference ranges are not diagnostic thresholds and this page cannot account for your medical history, medication or symptoms. Discuss any result that concerns you with a qualified clinician. See our medical disclaimer.