Oestrone is one of three types of oestrogen made by the body. The other types of oestrogen are called oestradiol and oestriol. Oestrone is primarily produced (either directly or from conversion of other hormones) by the ovaries as well as by adipose (fat) tissue and the adrenal glands. It has a much weaker biological activity than oestradiol. Oestrone is the major type of oestrogen hormone produced in postmenopausal women.
Very little is known about how the production of oestrone is controlled. In premenopausal women, some oestrone is produced by the ovaries. Oestrone is also produced by fat tissue and the adrenal glands, which are the main sources of oestrone in children, men and postmenopausal women. Because oestrone is less active than oestradiol, it is thought that oestrone may act as a reservoir that can be converted into oestradiol as needed. As women enter menopause the ovaries stop producing oestradiol. At this point the conversion of adrenal steroid hormones to oestrone takes over as the main source of oestrogen.
Increased oestrone production can occur in women with breast cancer and in men undergoing treatment for testicular or prostate cancer (which reduces testosterone production). Obese women also produce more oestrone from their fat tissues. Overproduction of oestrone within the breast may be associated with the development of breast cancer in women. Aside from this, oestrone production may affect health in both positive and negative ways, but the full extent of this is currently not known.
Low levels of oestrogens cause osteoporosis, fatigue, hot flushes, loss of libido and depression. As oestrone is the main oestrogen in postmenopausal women, it is thought that low levels may worsen these symptoms (which are also common during the menopause), particularly in the case of osteoporosis. However, further research is needed to confirm this.
Last reviewed: Feb 2021