Male Hormones

Testosterone is a hormone primarily responsible for male characteristics and is produced in the testicles of men, and to a much lesser extent, in the ovaries of women. It regulates sex drive and plays a crucial role in controlling bone mass, fat distribution, muscle mass, strength, as well as the production of red blood cells and sperm. Testosterone levels in men naturally decline after the age of 30, but lower than normal levels can occur at any age, causing symptoms such as low libido, erectile dysfunction, difficulty in gaining and maintaining muscle mass, and lack of energy. Women have much lower levels of testosterone than men, but it is equally important for regulating libido, muscle and fat distribution, and red blood cell formation. The normal reference range for testosterone levels varies slightly depending on the laboratory and population tested, but the British Society for Sexual Medicine recommends that low testosterone can be diagnosed when testosterone is consistently below the reference range, or when levels are below 12 nmol/L, especially in men who report symptoms of low testosterone or have low levels of free testosterone.

The majority of testosterone present in the bloodstream is bound to proteins, predominantly SHBG and albumin, with only a small amount (2-3%) existing in an unbound or free state, and thus available for use by cells. The test in question employs a formula to determine the level of free or unbound testosterone based on the total testosterone level, as well as levels of SHBG and albumin.

The free androgen index (FAI) is a calculated value that estimates the level of biologically active or "free" testosterone in the blood. Testosterone is an androgen hormone responsible for male sexual characteristics and is also present, although in smaller amounts, in females.

The FAI is determined by dividing the total testosterone level by the level of sex hormone-binding globulin (SHBG) and multiplying the result by 100. SHBG is a protein that binds to testosterone and other sex hormones in the bloodstream, limiting their availability for biological activity.

Prolactin is a hormone that is synthesized in the pituitary gland and is involved in the regulation of reproductive functions. Its main function is to stimulate lactation after delivery, and it is common for prolactin levels to increase substantially during pregnancy and breastfeeding in women.

Oestradiol is a steroid hormone that is primarily produced in the ovaries of women and to a lesser extent in the testes of men. It is one of three types of estrogen and has important functions in regulating the female reproductive system, as well as promoting breast tissue growth and maintaining bone density. Oestradiol levels naturally fluctuate throughout the menstrual cycle, peaking at ovulation in pre-menopausal women. As women age, their oestradiol levels decrease and eventually stop altogether with menopause. Low levels of oestradiol can lead to symptoms commonly associated with menopause such as hot flushes, night sweats, and mood swings. Additionally, low levels of oestradiol can increase the risk of developing osteoporosis.

Follicle Stimulating Hormone (FSH) is a hormone produced by the pituitary gland that plays a vital role in the reproductive systems of both men and women. In women, FSH helps stimulate the growth and development of follicles in the ovaries during the first half of the menstrual cycle. As follicles grow, they increase the levels of oestradiol, a hormone important for ovulation. One of these follicles eventually becomes dominant and is released during ovulation, after which FSH levels decrease in the second half of the cycle. In men, FSH acts on the seminiferous tubules of the testicles to promote the maturation of immature sperm cells into mature sperm.

Luteinising Hormone (LH) is a hormone produced by the pituitary gland that plays a crucial role in male and female fertility. In females, LH levels increase sharply around the middle of the menstrual cycle, causing ovulation to occur. It is also responsible for the formation of the corpus luteum, which produces progesterone to prepare the uterus for pregnancy. In males, LH stimulates the production of testosterone in the Leydig cells of the testes, which is essential for the development of male reproductive organs and secondary sexual characteristics.