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

Chief Medical Officer

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What is testosterone
and what does it do?

Testosterone is a male sex hormone produced by the testes in men's and women's ovaries and adrenal glands - but usually in smaller quantities. It governs many essential functions, such as sex drive (libido), energy levels, healthy bones, muscle mass, strength, and mood. In men, it also controls sperm production, so your levels can affect your fertility. Elevated testosterone in women can cause male characteristics, such as excessive hair, and is commonly associated with polycystic ovary syndrome. Heavy alcohol consumption, liver disease, and AAS (anabolic androgenic steroids) can reduce testosterone levels. Women taking oestrogen therapy may see increased testosterone levels.

What is oestradiol
and what does it do?

Oestradiol is a female steroid hormone produced in women's ovaries and, to a much lesser extent, in men's testes. It accounts for 80% of the oestrogen in the female body and is responsible for developing and maintaining the reproductive system, including fat distribution, preparing the follicles in the ovary for the release of an egg, and helping maintain bone density.

Men naturally convert some testosterone to oestradiol, and it's important for bone mass and sexual function. However, sometimes men can produce too much oestradiol compared with testosterone. This can result in female characteristics, especially the form of breast tissue (gynecomastia, moobs, or man-boobs).

What can I learn from a
Testosterone and Oestradiol Blood Test?

Our Testosterone and Oestradiol Blood Test can tell you your balance of testosterone and oestradiol. If you're a man, it can help you investigate symptoms of low testosterone and symptoms of high oestradiol (such as man-boobs) and check your hormones if you're taking testosterone replacement therapy (TRT). For women, this test can help investigate symptoms of high testosterone (such as excessive hair) and polycystic ovary syndrome.

What's Included?

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Oestradiol Oestradiol is a female steroid hormone, produced in the ovaries of women and to a much lesser extent in the testes of men. It is the strongest of three oestrogens and is responsible for the female reproductive system as well as the growth of breast tissue and bone thickness. In pre-menopausal women, oestradiol levels vary throughout the monthly cycle, peaking at ovulation. In women, oestradiol levels decline with age, culminating with the menopause when the ovaries stop producing eggs. Low oestradiol can cause many symptoms associated with the menopause, including hot flushes, night sweats and mood swings. Low oestradiol can also cause osteoporosis.
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.

How to prepare
for your test

Special Instructions

Prepare for your Testosterone and Oestradiol Blood Test by following these instructions. Please take your sample before 10am. Take this test two to five days after the start of your period, ideally on day three. It can be taken any time if you do not have periods. Hormonal contraception can affect this test, taking a break from this and using barrier contraception will give more accurate results. If you use hormone gels, pessaries, patches, or tablets, we strongly recommend selecting a venous sample to minimise contamination sometimes seen with finger-prick tests. Otherwise, administer any hormone supplements using gloves, and make sure your fingers have not been in contact with hormone supplements for at least four weeks before taking the test. Hormones can be absorbed deep within the skin even after minimal contact and remain there for weeks despite vigorous handwashing. Do not take biotin supplements for two days before this test, discuss this with your doctor if it is prescribed.

Frequently asked questions

Does this test measure high levels of testosterone?
Most testosterone tests set an upper detection limit of 52 nmol/L. If your result is higher than this, the lab will attempt a second measurement to get an actual reading, providing there is enough sample volume available. For this reason, we recommend taking a venous sample if you are expecting an abnormally high result (for example, if you take high doses of testosterone).