What it measures
- Total testosterone
Why measure testosterone?
Testosterone affects sex drive, erections, energy, mood, muscle and bone strength. Levels fall gradually with age, but a low level can also be caused by weight gain, type 2 diabetes, some medicines, poor sleep or problems with the testes or pituitary gland.
Getting a reliable result
Testosterone follows a daily rhythm and is highest in the morning, so please book before 11am. A low result is usually confirmed with a second morning test. To see how much of your testosterone is available to your body, add an SHBG test, or choose our Well Man Profile for a broader check.
Who it’s for
- Low sex drive or erectile problems
- Tiredness, low mood or poor concentration
- Reduced muscle strength or more body fat
- Monitoring testosterone treatment
How to prepare
- Drink plenty of water beforehand; it makes the sample quicker and easier to take.
- You don’t need to fast.
- Book a morning appointment, ideally before 11am, when testosterone is highest.
- Stop biotin (vitamin B7) supplements 48 hours before, as biotin can affect hormone and thyroid results.
Testosterone Blood Test: your questions
What time of day should I test testosterone?
In the morning, ideally before 11am, when levels are highest.
What are the symptoms of low testosterone?
Common symptoms include low sex drive, erectile problems, tiredness, low mood, poor concentration and loss of muscle strength.
Information on this page is general and doesn’t replace advice from your GP, midwife or consultant. If you feel unwell or are worried about symptoms, contact your GP, call NHS 111 or, in an emergency, 999.