Health: Second Opinion

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THIRTY YEARS may seem a long time to wait for the benefits of a medical treatment, but those seem to be the cost/benefit terms of hormone replacement treatment (HRT) with oestrogen to strengthen the bones.

Oestrogens have been used since the 1960s to treat some of the immediate symptoms of the menopause such as hot sweats. More recently enthusiasts have claimed that after the menopause a woman is in a state of permanent oestrogen depletion and that if HRT is given long-term it will slow the ageing of the skin, heart and bones and maintain sexual and psychic vitality. Doubters argue that the menopause is a natural event and that ageing should be accepted as inevitable.

Few of the research studies into HRT have lasted long enough to settle questions about the influence of hormones taken in middle age on the health of the body aged 80. But the population of a small town in Massachusetts has had its health assessed every two years since 1946. Many women living in Framingham took oestrogens as they became menopausal, and some of these women are now aged 70 to 80 years.

Most old women who suffer fractures do so after the age of 80, but the bones begin to lose strength - the process of osteoporosis - many years earlier. Between the ages of 50 and 80 a woman's bones lose on average 30 per cent of their substance. This decline is fast at first but then slows down. Oestrogen at the menopause halts the rapid bone loss, but if oestrogen is stopped - after five, 10, even 15 years - bone loss accelerates again for around five years; eventually the bones are much the same as if oestrogen had never been taken. Current thinking is that around 15 per cent of the bone mass is dependent on oestrogens - and this will be lost either in the five years after the menopause or in the five years after HRT is stopped.

The Framingham women had taken oestrogens for varying lengths of time, but few persisted with the treatment for more than 10 years. Those who took hormones for more than seven years had denser bones aged 60-65 than women who took no hormones - but by the age of 75 the difference in bone mass between past hormone takers and those who had never taken them was only 3 to 5 per cent.

So what conclusions should be drawn? The American doctors offer several strategies. Some women may be prepared to take hormones for 30 years or longer, until they die. Others may decide to start at the age of 70 if they think it likely that they will make it to 80. Treatment at that age has been shown to put some strength back into the bones. There are many other factors. Thin women who smoke are at greater risk of osteoporosis, and so are those whose mothers became osteoporotic in old age. Several studies have shown that women taking HRT have a lower risk of heart disease - but it is not yet known if this protection persists after treatment stops. Answers will emerge as more studies are done on women who have taken hormones for 20 or more years. Meanwhile the cautious may take comfort: it is never too late to start taking oestrogen. Treatment begun at 70 will increase bone density by 10 per cent in two years and if continued will reduce the risk of a fracture by one third.