Follicle Stimulating Hormone (FSH) is produced in the pituitary gland and plays a crucial role in both women and men. For women, FSH is essential in the ovaries' production of eggs, particularly in the first half of the menstrual cycle when it stimulates the growth of follicles. These follicles contribute to the rise in oestradiol levels. Eventually, one dominant follicle is released during ovulation, leading to a subsequent drop in FSH levels in the second half of the menstrual cycle.

In men, FSH acts on the seminiferous tubules within the testicles. Here, it stimulates the development of immature sperm cells into mature sperm. This highlights the pivotal role of FSH in reproductive processes for both women and men

Luteinising Hormone (LH) is generated by the pituitary gland and holds significance in both male and female fertility. In women, LH regulates the menstrual cycle and reaches its peak just before ovulation. For men, LH plays a key role in stimulating the production of testosterone, underscoring its crucial role in reproductive processes for both genders.

Oestradiol, is afemale steroid hormone, is predominantly produced in the ovaries of women and to a lesser extent in the testes of men. As the strongest among three estrogen types, oestradiol plays a pivotal role in the female reproductive system, breast tissue growth, and bone density. In pre-menopausal women, oestradiol levels fluctuate throughout the monthly cycle, reaching their peak at ovulation. With age, women experience a decline in oestradiol levels, culminating in menopause when the ovaries cease egg production. Low oestradiol levels can manifest in symptoms associated with menopause, such as hot flushes, night sweats, mood swings, and may also contribute to osteoporosis.

Thyroxine (T4), one of the thyroid hormones produced by the thyroid gland, plays a crucial role in accelerating metabolism. The majority of T4 is typically bound to carrier proteins in the blood. This test measures the free, or unbound, T4, which is the active form in the body. When free T4 levels are too low, it may result in symptoms such as fatigue, weight gain, and intolerance to cold, reflecting a potential underactive thyroid (hypothyroidism). Conversely, elevated levels of free T4 may lead to symptoms such as weight loss, nervousness, and heat intolerance, indicating a potential overactive thyroid (hyperthyroidism). Free T4, being the less active of the two primary thyroid hormones, requires conversion to a more active form when needed to exert its effects on cells. Maintaining an appropriate balance is crucial for overall thyroid function and well-being

Thyroid Stimulating Hormone (TSH) is manufactured in the pituitary gland to regulate the thyroid gland's production of thyroid hormones, thyroxine (T4) and triiodothyronine (T3). When the levels of thyroid hormones in the blood are low, increased TSH production stimulates the thyroid gland to produce more. Conversely, elevated thyroid hormone levels prompt the pituitary to reduce TSH production, slowing down thyroid hormone production. Abnormal TSH levels, whether too high or too low, often indicate an issue with the thyroid gland, leading to either underproduction or overproduction of thyroid hormones. Occasionally, disruptions in the pituitary gland can also result in irregular TSH levels.