Free Testosterone Blood Test, from our experts to you.
Dr Sam Rodgers MBBS, MRCGP

Chief Medical Officer meet our doctors

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What is
total testosterone?

Total testosterone is the amount of testosterone present in your body. However, not all this testosterone is available for the body to use because some of it is bound to a protein called sex hormone binding globulin (SHBG) and cannot be released to the cells. A proportion of testosterone is also loosely bound to another protein called albumin. The rest of the testosterone in the body (about 1-2%) is unbound or free for the cells to use.


What's included
in this test?

Our free testosterone test looks at your total testosterone, albumin, and SHBG levels to calculate the amount of testosterone available in your body for your cells to use.


Who is
this test for?

Our test is ideal for men who want to investigate low testosterone symptoms or who have previously had a normal or borderline-low result but still suffer symptoms. With this test, you can see how much free testosterone is available to your body’s tissues.


What's included?

Hormones
Proteins
Select profile for more information

Testosterone Testosterone is a hormone that causes male characteristics. For men, it helps to regulate sex drive and has a role in controlling bone mass, fat distribution, muscle mass, strength and the production of red blood cells and sperm. Testosterone is produced in the testicles of men and, in much smaller amounts, in the ovaries of women. Testosterone levels in men naturally decline after the age of 30, although lower than normal levels can occur at any age and can cause low libido, erectile dysfunction, difficulty in gaining and maintaining muscle mass and lack of energy. Although women have much lower amounts of testosterone than men, it is important for much the same reasons, playing a role in libido, the distribution of muscle and fat and the formation of red blood cells. All laboratories will slightly differ in the reference ranges they apply because they are based on the population they are testing. The normal range is set so that 95% of men will fall into it. For greater consistency, we use the guidance from the British Society for Sexual Medicine (BSSM) which advises that low testosterone can be diagnosed when testosterone is consistently below the reference range, and that levels below 12 nmol/L could also be considered low, especially in men who also report symptoms of low testosterone or who have low levels of free testosterone.
Free testosterone - calc Most testosterone circulating in the blood is bound to proteins, in particular SHBG and albumin; only 2-3 % of testosterone is free and available to cells. This test uses an algorithm to calculate the level of free or unbound testosterone in relation to total testosterone, SHBG and albumin.
Albumin Albumin is a protein which is made mainly in the liver. It helps to exert the osmotic pressure which holds water within the blood. It also helps carry nutrients and medications and other substances through the blood and is important for tissue growth and healing. Albumin also carries hormones around the body, therefore measuring the amount of albumin in the blood can help us calculate how much hormone is available to your tissues.
SHBG SHBG (sex hormone binding globulin) is a protein which transports the sex hormones (testosterone, oestrogen and dihydrotestosterone (DHT)) in the blood.Hormones which are bound to SHBG are inactive which means that they are unavailable to your cells. Measuring the level of SHBG in your blood gives important information about your levels of free or unbound hormones which are biologically active and available for use.

How to prepare
for your test

Special instructions

Prepare for your Free Testosterone Blood Test by following these instructions. Please take your sample before 10am. Avoid taking your sample from a finger used to apply hormone gels/pessaries in the past 4 weeks. Use gloves to apply these. Do not take biotin supplements for two days before this test, discuss this with your doctor if it is prescribed.


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