Follicle-stimulating hormone (FSH) is produced by pituitary gland and plays a key role in the reproductive system of both men and women. In women, FSH regulates the growth of ovarian follicles which secrete progesterone and Estrogen that are required for key events during the menstrual cycle. In men, FSH plays a key role in the development of the testes as well as the production of sperm.

Luteinizing hormone (LH) is produced in the anterior pituitary gland and plays an important role in regulating the function of the reproductive tissues which include the ovaries in females and testes in males.

In women, during the first half of a typical menstrual cycle (roughly weeks one to two), LH is required to stimulate the ovarian follicles that are located in the ovaries to produce the female sex hormone oestradiol. LH naturally rises at around day 14 of a women’s cycle and this surge is vital in stimulating the ovaries to release an egg during ovulation. Given fertilization occurs, LH also stimulates the corpus luteum, which secretes progesterone that is essential for sustaining pregnancy.

For men, LH plays a key role in stimulating the production of the main male sex hormone (testosterone) from Leydig cells present in the testes. Further to this, testosterone is then able to stimulate the production of sperm as well as contribute to the development of a set of characteristic traits which range from increased muscle and bone mass to the degree of bodily hair present.

LH also stimulates the production of testosterone in females. Consistently raised LH in women is often associated with polycystic ovary syndrome in which excessive amounts of testosterone are produced as a result of elevated LH. In contrast, low levels of LH may result in the halt of ovulation.

Low levels of LH may be a cause of infertility in both men and women due to levels being insufficient in stimulating sperm production or the ovulation process.

Oestradiol is an important steroid hormone that can be found in both men and women. In women, oestradiol is mainly produced by the ovaries and plays a key role in the maturation and maintenance of the female reproductive system.

In comparison, men produce considerably lower amounts of oestradiol. This is mainly produced by the testes where some testosterone is converted into oestradiol which is a vital component for the production of sperm. Oestradiol may also be produced to lesser extent by fat tissue in both men and women. Elevated levels of oestradiol may lead to a host of conditions ranging from depression to acne. A raised result has also been found to be associated with an increased risk of breast and uterine cancer. In contrast, low levels may affect the menstrual cycle, fertility, mental health or even lead to osteoporosis. In men, increased oestradiol can lead to infertility, loss of libido or the development of breast tissue. Levels may rise due to the accumulation of excessive fat tissue that secretes oestradiol.