How to diagnose hypogonadism in men?

Doctors base a diagnosis of low testosterone on the presence of 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.

Blood tests

Determination of testosterone values

Blood tests

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 may 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

Measurement of testosterone levels in the diagnosis of hypogonadism

Calculate the bioactive
testosterone circulating in plasma