WHAT IS A TESTOSTERONE BLOOD TEST FOR?

A testosterone blood test measures the level of testosterone in your blood, a hormone that plays a vital role in energy, muscle strength, fertility, and overall wellbeing. Both men and women produce testosterone, though in different amounts. When levels are too high or too low, it can affect mood, sexual health, and metabolism.

Testing your testosterone levels helps identify whether your body is producing the right amount of this hormone and can uncover the cause of symptoms such as fatigue, reduced libido, or difficulty building muscle. It can also support the diagnosis of hormonal conditions like polycystic ovary syndrome (PCOS) or hypogonadism.

If you want to check your hormone levels, you can book a testosterone blood test with One Day Tests. Our tests provide fast, lab-reviewed results, usually available the same or next working day, giving you a clear picture of your hormonal health.

A testosterone blood test measures how much testosterone is circulating in your bloodstream. There are two key types of testosterone that may be assessed: total testosterone and free testosterone.

Total testosterone measures both the testosterone that is bound to proteins and the smaller amount that is unbound. This gives an overall view of the total hormone level in your body.

Free testosterone measures only the unbound portion, the part that is biologically active and available for your body to use.

In some cases, other related markers such as sex hormone-binding globulin (SHBG), luteinising hormone (LH), and follicle-stimulating hormone (FSH) may also be tested. These provide a clearer picture of how your body is regulating testosterone production and can help determine whether the issue lies with the testes, ovaries, or pituitary gland.

At One Day Tests, testosterone is analysed using modern laboratory technology to ensure accuracy and reliability. This provides clear results that help guide next steps if an imbalance is detected.

Doctors may recommend a testosterone test to investigate a range of symptoms or conditions that suggest hormone imbalance.

In men, the test is often used to check for:

• Reduced sex drive or erectile changes
  
  

• Fatigue, low energy, or loss of muscle strength
  
  

• Mood changes, such as low mood or irritability
  
  

• Fertility concerns or low sperm count
  
  

• Delayed puberty in younger males
  
  

In women, testosterone testing is helpful for identifying:

• Symptoms of PCOS, including irregular periods, acne, or unwanted hair growth
  
  

• Hormonal imbalance that may affect fertility
  
  

• Monitoring hormone levels if taking hormone replacement therapy (HRT) or testosterone-based treatment
  
  

A testosterone test may also be ordered to monitor ongoing treatment or assess how well hormone replacement therapy is working. Regular testing ensures testosterone stays within a healthy range and helps doctors adjust treatment if necessary.

Abnormal testosterone levels can point to a range of underlying conditions.

• Hypogonadism: When the testes or ovaries produce too little testosterone due to problems with the glands or hormone signalling.
  
  

• PCOS (Polycystic Ovary Syndrome): In women, high testosterone levels can lead to irregular cycles and fertility difficulties.
  
  

• Pituitary or adrenal disorders: Problems with these glands can disrupt the signals that control testosterone production.
  
  

• Tumours: Rarely, tumours in the adrenal glands or testes can cause excessive testosterone production.
  
  

• Infertility: Testosterone plays an important role in sperm and egg development, so abnormal levels can affect conception.
  
  

Testing testosterone can help identify whether these conditions are hormone-related, guiding doctors toward the right investigations or treatments.

To get the most accurate results, timing and preparation are important. Testosterone levels are usually highest in the morning, so the best time to take the test is between 7 am and 11 am.

It’s also useful to:

• Avoid finger-prick testing if using topical testosterone gels, as residue can affect the sample.
  
  

• Mention any hormone therapy or contraceptive medication, as some treatments (such as combined contraceptive pills) can affect SHBG levels and make free testosterone appear lower.
  
  

• Fasting is not always required, but your clinician may recommend it if other tests are being done at the same time.
  
  

At One Day Tests, we provide clear pre-test guidance to ensure your results are as accurate as possible. Once your sample arrives at our accredited laboratory, your results are processed quickly and securely with most people receiving them the same or next working day.