Total Testosteronenmol/L
Total circulating androgen level
Also known as: Testosterone, Testosterone (total)
Typical optimal range
8.6–29 nmol/L
Female
A commonly cited optimal range for total testosterone is roughly 8.6–29 nmol/L, though reference intervals vary between laboratories and differ significantly between sexes, so your result should always be interpreted against the range provided by the lab that processed your sample. These figures are indicative — the range printed on your own lab report is the definitive one for your results.
Interpretation and management of testosterone results in the UK follows NHS and NICE guidance, including NICE guideline NG242 on testosterone deficiency in adults, alongside local laboratory reference intervals.
What is Total Testosterone?
Testosterone is the body's primary androgen hormone, produced mainly in the testes in men and in smaller amounts by the ovaries and adrenal glands in women. It plays a central role in maintaining muscle mass, bone density, libido, mood, and metabolic health across both sexes. A blood test measures total testosterone, which includes both the fraction bound to proteins (mainly sex hormone-binding globulin and albumin) and the smaller free fraction. Measuring it helps identify hormonal imbalances that may explain symptoms and guides decisions about further investigation or treatment.
What a high Total Testosterone means
A total testosterone result above the laboratory's reference interval is worth discussing with your GP, as it is uncommon naturally and may point to an underlying cause that warrants further assessment.
- Exogenous testosterone or anabolic steroids. The most frequent reason for a raised result in clinical practice is the use of testosterone replacement therapy (TRT) or anabolic steroids. If you are on prescribed TRT, your GP will monitor levels to keep them within a therapeutic range.
- Polycystic ovary syndrome (PCOS) in women. In women, elevated testosterone is one of the biochemical features of PCOS, a common hormonal condition. It may accompany symptoms such as irregular periods, excess hair growth, or acne, and warrants further hormone testing.
- Rare androgen-secreting tumours. Adrenal or ovarian tumours that secrete androgens are uncommon but can produce markedly elevated levels. Rapid onset of symptoms alongside very high results is a reason for prompt GP review.
A mildly elevated result can sometimes reflect the time of sampling (testosterone peaks in the morning), laboratory variation, or certain medications; a repeat test is usually arranged before further investigation.
What a low Total Testosterone means
A total testosterone result below the laboratory's reference range can be a meaningful finding, particularly when it accompanies symptoms such as persistent fatigue, low libido, poor recovery from exercise, loss of muscle bulk, or low mood.
- Ageing. Testosterone declines gradually with age in men — typically from the late thirties onwards — which is a normal physiological process, though the extent varies considerably between individuals.
- Excess body fat, poor sleep, and chronic stress. Visceral adiposity increases conversion of testosterone to oestrogen via aromatase activity; chronically disrupted sleep and elevated cortisol from ongoing stress both suppress the hypothalamic-pituitary-gonadal axis, reducing testosterone production.
- Medications. Several commonly prescribed medicines — including opioid analgesics and, to a lesser extent, some antidepressants (SSRIs) — can suppress testosterone levels; always mention your current medications when discussing results with your GP.
A single low result should be confirmed with a repeat morning sample before any diagnosis is made, as levels fluctuate and results can be affected by acute illness, significant recent weight change, or simply the time of day.
Should I be worried?
A single out-of-range testosterone result on its own is rarely cause for alarm — it is a prompt to look more closely rather than a diagnosis. Most GPs will arrange a repeat fasting morning sample alongside related markers such as LH, FSH, SHBG, and prolactin before drawing any conclusions, as this gives a much clearer picture of what the hormonal system is doing. If your result sits alongside symptoms that are affecting your quality of life, that is a good reason to book a GP appointment rather than waiting; equally, if you feel well and the deviation is modest, a calm conversation at your next routine review is entirely appropriate. Avoid making changes to diet, exercise, or any medication on the basis of a single result.
What actually helps
Several well-evidenced lifestyle habits support healthy testosterone levels, particularly when levels are on the lower side.
- Resistance training. Progressive resistance exercise is one of the most consistently supported lifestyle interventions for maintaining testosterone, particularly as it also reduces visceral fat and improves insulin sensitivity — both of which matter for hormonal health.
- Prioritise sleep quality and quantity. Testosterone is predominantly secreted during sleep; studies show that restricting sleep to five hours or fewer can reduce daytime testosterone levels substantially. Aiming for seven to nine hours of good-quality sleep each night is one of the most practical steps you can take.
- Reduce excess body fat. Visceral fat promotes conversion of testosterone to oestrogen; evidence shows that meaningful weight loss in men with overweight or obesity is associated with clinically relevant rises in testosterone, often without any other intervention.
- Address vitamin D and zinc status. Both vitamin D and zinc are needed for testosterone synthesis; deficiency in either is associated with lower levels. The NHS recommends a daily 10 µg vitamin D supplement for most adults during autumn and winter; zinc is best obtained through food rather than high-dose supplements.
Good supporting evidence exists for the following dietary choices as part of a balanced diet that sustains testosterone.
Eggs
Provide dietary cholesterol (a precursor to steroid hormones), zinc, and vitamin D — all relevant to androgen synthesis.
Oily fish (salmon, mackerel, sardines)
A practical dietary source of vitamin D and omega-3 fatty acids; some evidence links higher omega-3 intake with better hormonal profiles.
Shellfish, particularly oysters
Among the richest dietary sources of zinc, a mineral essential for the enzymes involved in testosterone production.
Nuts and seeds (pumpkin seeds, Brazil nuts)
Pumpkin seeds provide zinc and magnesium; Brazil nuts supply selenium — micronutrients with roles in testicular function and antioxidant protection.
Leafy green vegetables (spinach, kale)
Rich in magnesium, which has been associated with higher free and total testosterone levels, particularly in physically active individuals.
Wholegrains and legumes
Support a healthy body weight and insulin sensitivity, both of which have downstream benefits for the hypothalamic-pituitary-gonadal axis.
Track your own Total Testosterone
Upload a lab PDF and Better Days trends Total Testosterone over time, flags it when it drifts, and suggests foods that help.
More in Hormones
Sources & further reading
These are reputable UK health resources for further reading. This page is written to be consistent with their guidance but is not a substitute for them.
For information only — not medical advice, and not individually reviewed by a clinician. Reference ranges vary by lab and individual. Discuss any results with a qualified clinician before making changes.