Every woman who reaches midlife will experience menopause when her ovaries eventually run out of eggs.

The average age of natural menopause in Australia is 51 years. But around 10% of women experience menopause before the age of 45, and 1% before 40. Early menopause can be spontaneous, or due to surgical removal of both ovaries, or brought on by treatments such as chemotherapy.

After menopause, the ovaries are no longer able to produce the sex hormones essential for reproduction. As a result, blood levels of oestrogen and progesterone are very low.

Blood levels of testosterone don’t change with natural menopause, but decline in the decade leading up to the menopause. Women who have had their ovaries surgically removed have lower testosterone levels than other women.

The months surrounding menopause are called the perimenopause. It’s a period of hormonal chaos that generally lasts about two years. Women may experience perimenopausal symptoms that at times reflect high oestrogen levels due to the ovaries working harder: sore swollen breasts, heavy bleeding, periods closer together.

At other times they may have symptoms of low oestrogen due to the ovaries running down: missed periods, hot flushes, night sweats, lowered mood, anxiety and sleep disturbances.

Some women breeze through perimenopause and never have a symptom, whereas others have a horrid time.

Symptoms

Most symptoms that follow menopause are due to low oestrogen. The most common are hot flushes and night sweats, which affect three-quarters of post-menopausal women and are severely bothersome for one in three women.

Most women will have hot flushes and night sweats for an average of 4.5 years after their menopause, although many women have symptoms into their 60s. Contrary to some beliefs, women in developing and developed countries experience hot flushes and night sweats; they’re not symptoms of westernisation.

Other common symptoms of perimenopause and menopause include mood changes (anxiety and depressed mood), vaginal dryness resulting in painful intercourse, frequent urination and sexual dysfunction, particularly lowered libido.

Women start to lose bone around two years before menopause. This accelerates during perimenopause, and slows about two to seven years after menopause. Low body weight is a major risk factor for bone loss at this time.

Menopause-related bone loss occurs because the fall in oestrogen production accelerates bone breakdown, which is not compensated for by bone formation. Bone loss can, however, be prevented or reversed by oestrogen therapy.

Menopause also results in metabolic changes that may predispose women to heart disease and diabetes.

Treatment

Severe menopausal symptoms can be debilitating. Moderate to severely bothersome hot flushes and night sweats are associated with lowered personal and general well-being and an impaired ability to work.

Thankfully, women can choose from a range of effective hormonal and non-hormonal treatments to alleviate symptoms. Her choice will be based on how bothered she is by the symptoms, her current health status and her personal expectations.

Menopausal hormone therapy is the most effective treatment option, but comes with an increased risk of some cancers if used for extended periods. However, it is internationally accepted that for most women within ten years of menopause and or who are less than 60 years of age, the benefits of menopausal hormone therapy outweigh the risks.

Unfortunately, myths of the dangers of menopausal hormone therapy have been widely and inappropriately propagated, resulting in many women with severe symptoms not receiving effective treatment. It has also prompted some women to resort to complementary therapies that lack proven efficacy, and untested and unregulated compounded hormone therapy.

Compounded hormones are promoted as being “bioidentical”, but they are made using the same hormones used in approved menopausal hormone therapy. There is no evidence that compounded hormone therapy is more or less safe than approved therapies, although it is usually more expensive and the hormonal blood levels cannot be predicted.

Non-hormonal treatment options to reduce hot flushes and night sweats include low-dose antidepressants the anti-epliepsy medicine gabapentin and the neuropathic pain drug pregabalin. But none are as effective as standard dose hormone therapy. Other potential non-hormonal therapies to alleviate hot flushes are being investigated.

Hypnosis and cognitive behaviour therapy have been shown to have some benefit for hot flushes and night sweats. However, quality clinical studies have not shown yoga, exercise or acupuncture to be more effective than placebo therapy.

This article is part of an occasional series, Chemical Messengers, on hormones and the body.