Testosterone is a word many have heard of, but may not know a lot about. To some, the word may be an unknown entity that sweaty rugby players charging around a field probably have plenty of, but nobody knows why or what specifically it is. To some, testosterone is purely linked to the display of aggressive behaviour, but it is more complex than that. Testosterone is actually the principal male sex hormone derived from the androgen group and is an essential factor in sexual and reproductive development, produced primarily in the testes.  It helps a number of important functions such as muscle mass/strength, sex drive, sperm production, fat distribution, bone density and red blood cell production. The development of secondary sex characteristics at puberty is also aided by testosterone, such as voice deepening and growth of facial and body hair. Testosterone is also present in women too, but at substantially lower amounts than those found in men. In women, testosterone is generated within the ovaries and adrenal glands, with their levels at an estimated tenth to a twentieth of man’s levels. As it is a steroid hormone, testosterone is derived from cholesterol. Low testosterone Levels of testosterone are known to decrease over time with age, but many health experts are in disagreement about what brings on ‘Low T’, known as hypogonadism, and the topic is often a controversial one. Men typically receive treatment for hypogonadism if their testosterone levels are below 300 nanograms per decilitre and they are showing symptoms of low testosterone. Many men are terrified that dwindling levels of testosterone will lead to a huge drop in sexual desire and performance will be impacted. As men advance in their years, sexual function could be affected by lowered levels of the hormone, including: . Infertility. . Less desire for sex. . Erectile dysfunction (ED), or less erections that may occur randomly, such as during sleep. The link between ED and testosterone is not fully understood, however low testosterone levels are with the same health conditions that have been linked to ED, such as type 2 diabetes, obesity and heart disease. Other low T symptoms may include: . Losing muscle mass. . Decreased energy. . Increased body fat. . Depression/bad mood. Low T treatment depends mainly on what you and your doctor deem to be the most suitable for you. Gels and Solutions Testosterone gels and solutions are applied each day, with the testosterone in the gel being absorbed directly through the skin when you apply the gel or solution. Patches Patches mean testosterone can be absorbed by the skin and are normally worn on the arm or upper body. They are applied once each day. Injections and implants Testosterone injections are typically administered into the upper buttock, every 1-2 weeks by your doctor. Testosterone may also be implanted as pellets within soft tissues. The testosterone is slowly absorbed by your body into the bloodstream. High testosterone If a woman’s body produces too much testosterone, she may experience irregular or absent menstrual periods and excessive body hair (hirsutism). In addition, frontal balding – similar to male pattern baldness -  is another sign that a woman has high testosterone levels as well as suffering with acne, increased perspiration, an enlarged clitoris, increased muscle mass and their voice deepening. However, the good news is that a combined anti-testosterone (androgen) and oestrogen medicine named Dianette (Cyproterone Acetate / Ethinylestradiol) can be prescribed for women with these problems. Not only does it work as an oral contraceptive pill, Dianette can be prescribed to regulate periods, combat excessive hair growth on the face and body (hirsutism) in women, help to reduce acne which hasn’t improved after the long-term use of oral antibiotics in women and can help women who suffer with female hair loss.