of low testosterone depends on persistent symptoms and test results

How is testosterone deficiency diagnosed?

Doctors base a diagnosis of low testosterone on the presence of persistent symptoms and the results of blood tests that measure testosterone levels.

Your doctor will ask you some questions to help understand what signs or symptoms you may be experiencing that suggest you have low testosterone. The symptom most associated with low testosterone is reduced sex drive (low libido), however your doctor will ask about a range of symptoms.

Because many of these symptoms are not necessarily only due to low testosterone, your doctor will perform a physical exam and may take a blood sample to measure testosterone levels.

Physical exam

  • General examination including blood pressure
  • Evaluation of secondary sexual characteristics (body hair density and distribution, beard growth)
  • Testicle examination
  • Waist circumference measurement and distribution of fat

Blood test

  • Blood will usually be taken in the morning (between 7.00am and 11.00am) when testosterone in your blood is naturally at its highest level
  • Most of the testosterone in your blood is bound tightly by a protein called sex hormone-binding globulin (SHBG) and so it is not free to do its job. Because of this your blood may also be tested for levels of SHBG in order to work out how much of the total testosterone is free testosterone (also known as bioavailable or bioactive testosterone)
  • The results of these tests will need to be confirmed by taking a second sample
  • If tests confirm that you have low testosterone, additional tests may be required and you may be referred to a specialist. Your doctor will advise you of what additional tests are needed