Testosterone
Serum Testosterone
What this test measures
Testosterone is the main male sex hormone, though women also produce small amounts. It's important for muscle mass, bone density, sex drive, and mood.
Understanding the numbers
Typical range: Men: 8.0-30.0 nmol/L | Women: 0.5-2.5 nmol/L
Testosterone is best measured in the morning when levels are highest. Levels naturally decline with age in men.
- Low (men): 0–8 nmol/L
- Normal (men): 8–30 nmol/L
- Raised (women or men on TRT): 30–40 nmol/L
Key numbers
- 8 nmol/L — Men — lower limit
- 12 nmol/L — Men with symptoms — treat below this per BSSM guidance
- 30 nmol/L — Men — upper limit
British Society for Sexual Medicine (BSSM) guidance: a single total testosterone is not enough — confirm with a morning repeat, calculate free testosterone, and check LH and SHBG. Treatment is considered for men with consistent symptoms and total testosterone below ~12 nmol/L. In women, high testosterone suggests PCOS or androgen excess.
Ranges can vary slightly between laboratories — your report may show slightly different numbers. This page does not read or interpret your result; your GP looks at it alongside your history and other tests.
What a higher-than-normal result can mean
- In women, may indicate polycystic ovary syndrome (PCOS)
- Can cause excess hair growth, acne, or irregular periods in women
- In men, usually only high if taking testosterone supplements
- Rarely, can be caused by tumours of the adrenal gland or ovaries
Questions you could ask your GP
- What might be causing my abnormal testosterone level?
- Do I need further hormone tests?
- Could this explain my symptoms?
- Would testosterone replacement therapy help me?
Example stories
These are made-up examples to show how results are talked about in real appointments. They are not real patients.
Late-onset hypogonadism
Ankit had low libido, fatigue and poor morning erections. Two 9am testosterone results were 6.8 and 7.4 nmol/L. LH was low-normal.
What the GP said: “Two morning samples confirm low testosterone. We'll discuss testosterone replacement therapy — it helps symptoms, but it suppresses fertility and needs monitoring for haematocrit, PSA and bone density.”
What happened next: Ankit started testosterone gel; after three months his testosterone was in range and symptoms improved.
Diagnosing low testosterone needs at least two morning samples plus clinical symptoms — not a single number. TRT helps symptomatic men but has important side effects and needs long-term monitoring.
Congenital hypogonadism
Ryan had poor pubertal development and was referred from school. Testosterone 3.2, LH raised, Klinefelter karyotype (47,XXY).
What the GP said: “This is Klinefelter syndrome — one extra X chromosome affects testicular function. Testosterone replacement from now gives you puberty and helps long-term bone, muscle and mood health.”
What happened next: Long-acting testosterone injections produced pubertal development; fertility was planned via sperm retrieval for the future.
Young men with very low testosterone and raised LH have primary testicular failure. Klinefelter is common but often missed until adulthood — starting replacement matters for development, bone health, and mental wellbeing.
PCOS — raised testosterone in a woman
Sunita had irregular periods, acne, and coarse facial hair. Testosterone 3.8 nmol/L, LH:FSH ratio raised, ultrasound showed polycystic ovaries.
What the GP said: “This is polycystic ovary syndrome. Weight, diet and lifestyle are a first line; we can also use the combined pill or spironolactone for the androgenic symptoms.”
What happened next: With 6 kg weight loss and a combined pill, her cycles regularised and acne and hair growth improved.
In women, raised testosterone, menstrual irregularity and polycystic ovaries on scan make PCOS the diagnosis. Lifestyle is powerful; pharmacological options help with symptoms and future fertility.
Age-related decline — symptoms from other causes
Owen had low libido, fatigue, and poor sleep. Testosterone 10.2 nmol/L — at the lower end. HbA1c raised, sleep disorder on history.
What the GP said: “Your testosterone is at the lower end but within range. Fatigue and libido often come from sleep, blood pressure, blood sugar, and depression — let's address those first rather than treat the testosterone.”
What happened next: Sleep study confirmed OSA; CPAP improved sleep and symptoms; HbA1c came down with lifestyle change.
A low-normal testosterone in an older man with multiple competing causes isn't automatic grounds for TRT. Sleep apnoea, depression, diabetes and medication side effects often explain symptoms and respond to their own treatment.
Before you act on anything here
This page is general information, written to help you understand — it is not personal medical advice and it cannot tell you what is right for you. Talk to your own GP, pharmacist or nurse about your own health.
- Need help now but it's not an emergency? Call NHS 111 or use 111.nhs.uk.
- Emergency? Call 999 or go to A&E.