Optimal Ranges
What is the optimal range for Testosterone?
Clinical (NHS) Range
8.64-29 nmol/L
nmol/L
Performance-Optimised Range
20-30 nmol/L
nmol/L
| Range | Value | Unit |
|---|---|---|
| Clinical (NHS) reference range | 8.64-29 nmol/L | nmol/L |
| Performance-optimised range | 20-30 nmol/L | nmol/L |
The clinical range defines what is considered medically “normal” — broad enough to cover 95% of the population. The performance range reflects where research and clinical experience suggest most people feel and function at their best. A result in either range suggests typical status and is not a diagnosis; any individual reading should be interpreted by a qualified clinician.
Why It Matters
Why Testosterone matters for performance
Testosterone is the single most important hormone for male physical and mental performance. Low testosterone is associated with reduced muscle mass, increased body fat, poor sleep quality, low libido, and impaired cognitive function. Many men in their 30s and 40s have testosterone levels that are technically 'normal' but functionally suboptimal. Optimising the factors that support testosterone production — vitamin D, zinc, magnesium, sleep, and body composition — can meaningfully shift levels without medical intervention.
Symptoms
What are the symptoms of low or high Testosterone?
Low / Deficiency
- Reduced muscle mass and strength
- Increased body fat, especially visceral
- Low libido and erectile dysfunction
- Fatigue and brain fog
- Depressed mood and irritability
- Poor sleep quality
High / Excess
- Acne and oily skin
- Aggression and mood swings
- Sleep apnoea
- Elevated red blood cell count
Dietary Sources
Which foods support Testosterone levels?
Supplementation
How do you improve Testosterone levels?
Direct testosterone supplementation requires medical supervision (TRT). However, supporting nutrients that influence testosterone production include zinc (30 mg/day if deficient), magnesium (400 mg glycinate), vitamin D3, and ashwagandha (600 mg KSM-66). Prioritise sleep quality, resistance training, and maintaining body fat below 20% as foundational interventions.
Testing
How is Testosterone tested in the UK?
Testosterone is measured from a blood sample. With Helvy, that means a finger-prick kit taken at home and posted to a UKAS-accredited UK laboratory, with results in around 5 days, reviewed by a qualified clinician. Your result is reported against both the clinical range (8.64-29 nmol/L) and the performance-optimal range (20-30 nmol/L), so you can see not just whether you are “normal” but whether you are optimal. If you make a change, retest after 8-12 weeks to confirm it worked.
Research
Key study
Testosterone and cortisol in relationship to dietary nutrients and resistance exercise
Volek JS, Kraemer WJ, Bush JA, et al.
Journal of Applied Physiology (1997)
DOI: 10.1152/jappl.1997.82.1.49Related Biomarkers
Related Guides
Explore Testosterone in depth
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Order Your TestThis content is for educational purposes only and does not constitute medical advice. Your data suggests areas for optimisation, but any concerns should be discussed with a qualified healthcare professional. If your results flag values outside safe ranges, we recommend consulting your GP.