The Oestrone (E1) blood test measures the level of oestrone, one of the three main forms of oestrogen produced in the body. Oestrone plays a particularly important role after menopause, when it becomes the predominant circulating oestrogen.

Oestrogens are essential hormones involved in the regulation of the menstrual cycle, reproductive health, bone density, cardiovascular function, and overall hormonal balance. While oestradiol (E2) is the dominant oestrogen during reproductive years, oestrone becomes more influential as ovarian function declines.

Oestrone is produced primarily through the conversion of adrenal hormones in fat tissue. As a result, body composition, metabolic health, and adrenal function can significantly influence oestrone levels. This makes the test particularly useful when assessing hormonal balance in peri-menopausal and post-menopausal individuals.

Abnormal oestrone levels may be associated with a range of symptoms. Elevated levels can contribute to oestrogen dominance, which may present as weight gain, breast tenderness, bloating, mood changes, or irregular bleeding. Low levels may be associated with menopausal symptoms such as hot flushes, night sweats, low mood, and reduced bone density.

The Oestrone test is often requested alongside other hormone tests, such as oestradiol, progesterone, FSH, and LH, to provide a more complete picture of hormonal status. It may also be used when monitoring hormone replacement therapy or investigating endocrine disorders.