What are testosterone and oestradiol?

Testosterone is a steroid hormone that plays a key role in the development of the male reproductive system, muscle mass and body hair. Testosterone levels decline with age in males, a process known as andropause, resulting in physiological changes including reduced muscle strength and bone density. Testosterone also has important functions in women contributing to bone health, fertility, menstrual cycle and sex drive. Oestradiol is the strongest and most common of three naturally produced oestrogen hormones. It is important for female reproductive development and is critical for the menstrual cycle. In males, oestradiol is important for sperm production.

Oestradiol is also produced in small amounts in fat tissue, the brain and blood vessels. Hormones are chemical messengers used by the body to respond to internal and external influences. The activity of hormones must be finely regulated to produce the desired physiological effect. This regulation is typically coordinated by complex interactions between several different hormones. Both excessive production and a deficiency in the production of steroid hormones can cause ill health. Testosterone can be produced to oestradiol in males causing an increase in female characteristics. In contrast, excess testosterone in females results in male characteristics.

Symptoms of low testosterone include reduced bone and muscle mass and low sex drive. In females, elevated oestradiol can result in weight gain, depression, infertility and increased risk of stroke or heart attack. In males, it can result in increased body fat, reduced muscle, sexual dysfunction and the development of female physiological characteristics such as breast tissue. Oestradiol deficiency is associated with bone conditions such as osteoporosis.

Why take the test?

This test measures the amount of testosterone and oestradiol in the blood. This test can be used to investigate the balance of the body’s main sex hormones to investigate fertility problems, low sex drive, erectile dysfunction in males and polycystic ovary syndrome (POCS) in females.