Testosterone and Oestradiol Blood Test Kit

Testosterone is the primary androgen (male sex hormone), though it plays important roles in both sexes. In men, testosterone is produced mainly by the Leydig cells in the testes, with smaller amounts from the adrenal glands. It's responsible for the development of male characteristics during puberty and continues to regulate libido, erectile function, sperm production, muscle mass and strength, bone density, fat distribution, red blood cell production, and mood throughout adult life. Normal testosterone in men is typically 8.6-29 nmol/L, declining gradually (approximately 1-2% per year) after age 30. In women, testosterone is produced by the ovaries and adrenal glands in much smaller amounts (normal range approximately 0.5-2.5 nmol/L). Despite the lower levels, testosterone is important for women's libido, energy, muscle tone, bone health, and general wellbeing. Excess testosterone in women can cause symptoms of androgen excess: acne, oily skin, excess facial and body hair (hirsutism), scalp hair thinning, and menstrual irregularities. This pattern is often seen in polycystic ovary syndrome (PCOS). The relationship between testosterone and oestradiol is important because testosterone can be converted to oestradiol by the enzyme aromatase, found primarily in fat tissue. In men with higher body fat, more testosterone is aromatised to oestradiol, potentially causing symptoms of relative oestrogen excess (breast tenderness, gynaecomastia) alongside symptoms of testosterone deficiency. This is why checking both hormones together provides more complete information than either alone. Results outside the normal range may need a follow-up with your GP.

Oestradiol is the most potent and abundant of the three oestrogens (oestradiol, oestrone, oestriol). In premenopausal women, oestradiol is produced primarily by the ovaries and is the dominant oestrogen. It regulates the menstrual cycle, promotes development of female secondary sexual characteristics, maintains the uterine lining, supports bone density, affects cholesterol metabolism (generally protective for cardiovascular health), influences mood and cognition, and has numerous other effects throughout the body. Oestradiol levels vary dramatically across the menstrual cycle: low in the early follicular phase (typically 100-400 pmol/L), rising to a pre-ovulatory peak (400-1500+ pmol/L), then settling to moderate levels in the luteal phase. After menopause, ovarian oestradiol production ceases and levels fall dramatically (typically below 100 pmol/L). This oestrogen withdrawal causes menopausal symptoms: hot flushes, night sweats, vaginal dryness, mood changes, sleep disturbance, and accelerated bone loss. Hormone replacement therapy (HRT) restores oestradiol levels to relieve these symptoms and protect bone health. In men, oestradiol is produced primarily through aromatisation of testosterone in peripheral tissues (fat, liver, muscle, bone). Normal oestradiol in men is typically 40-160 pmol/L. Men need some oestradiol—it's important for bone health, brain function, and even libido. However, excess oestradiol in men can cause problems: gynaecomastia (breast tissue enlargement), water retention, mood changes, and can contribute to erectile dysfunction. Men on testosterone replacement therapy need to monitor oestradiol because exogenous testosterone can be aromatised to oestradiol; if levels become excessive, symptoms may develop and aromatase inhibitors may be considered (though these should be used cautiously due to their own effects on bone health and lipids). Results outside the normal range may need a follow-up with your GP.