Produced by the National Osteoporosis Society, February 2004
(The NOS website hosts the original version of this document, in Microsoft Word format. It is reproduced here with permission.)
During childhood and adolescence, bones grow in size and density. Bone needs to be stimulated to grow and become strong and also requires a good supply of calcium. Both diet and exercise help to do this. A well balanced, calcium rich diet and regular exercise such as running, skipping, brisk walking, aerobics and weight training all help to strengthen bones. At puberty, the bone density receives a boost as the effects of oestrogen and testosterone increase bone mass.
Both sex hormones are necessary to bone health as once they decline or are stopped (as in replacement therapy for a transsexual person), bone density begins to be lost. This is because the cells which break down bone, without the influence of the hormones, begin to work faster than the cells making new bone so a deficiency in bone density occurs.
Osteoporosis literally means “porous bones”. The bones in our skeleton are made of a thick outer shell and a strong inner mesh filled with collagen (protein), calcium salts and other minerals. The inside looks like a honeycomb, with blood vessels and bone marrow in the spaces between the struts of bone. Osteoporosis means some of these struts become thin or break without too much force. It often remains undetected until the time of the first fracture. The wrist, hip and spine are the sites at which fractures most commonly occur.
Women are more at risk of developing osteoporosis than men due to their lower peak bone density and the rapid loss of bone density at the time of the menopause.
In the male to female transsexual person, testosterone production is stopped. Oestrogen, with or without a progestogen, is taken to give a more feminine appearance. In the female to male transsexual person the opposite applies. Both of these sex hormones (testosterone for men and oestrogen for women) are necessary to maintain bone density. The transsexual person becomes at risk of developing osteoporosis if the sex hormones (replacement or natural) are discontinued leaving them with no hormones of either kind. The female to male transsexual person may also experience menopausal symptoms due to the lack of their bodies’ natural oestrogen and irrespective of whether they stop hormonal treatment or not, tend to lose bone density. Hormone therapy needs to be continued on a long term basis to prevent osteoporosis.
There are several risk factors for developing osteoporosis and these include:
A lack of oestrogen caused by:
A bone density scan called a dual energy x-ray absorptiometry (DXA) scan is the most accurate way to measure the density and strength of bones and also risk of fracture. The scan is a simple, painless procedure that uses very low doses of radiation and takes only a few minutes. The usual sites of measurement are the hip and lower spine but sometimes the forearm (wrist) is used.
The normal ranges of these measurements are dependent upon the sex of the individual. In people who have had medical or surgical interventions to change their sex, experts believe that the range of measurements used should be those which reflect the sex of the individual at birth because these most closely reflect the skeletal size and fracture risk for an individual.
One of the major risks associated with female hormone use is deep vein thrombosis (DVT), although this is less likely using a patch form of oestrogen replacement. This is the formation of a blood clot usually in the lower leg. Blood clots can occur in other places such as the lungs. This is known as a pulmonary embolism (PE). Although rare, a PE can be life threatening. Oestrogen therapy is usually discontinued prior to any type of major surgery. It is therefore, important to discuss this with your consultant as immobilisation during and following surgery will also increase the risk of a blood clot developing. Initially, the female hormone oestrogen can cause nausea but this should disappear as the body becomes used to the treatment. Fluid retention and a raised blood pressure (hypertension) may also be seen with oestrogen therapy.
If a progestogen is used with the oestrogen, mood swings similar to pre menstrual tension (PMT) may occur. Not all transsexual women are given a progestogen as this is given to help mimic the hormonal cycle experienced by women but not all wish to have this effect.
Following administration of anti androgens (drugs which block testosterone production in the male to female transsexual person), there may be an increased risk of stroke and arteriosclerosis (thickening of the arterial walls due to ageing or high blood pressure often called ‘hardening of the arteries’) and liver disease. The side effects associated with testosterone replacement therapy include acne, cardiovascular disease and in some cases, abnormal liver function. Hormone replacement therapy (HRT) should only be used with medical supervision where its effects should be monitored.
There are several drugs licensed for the prevention and treatment of osteoporosis. These include the bisphosphonates, alendronate (Fosamax), risedronate (Actonel) and cyclical etidronate (Didronel PMO). These are non hormonal, specific drugs to prevent bone density loss and reduce the risk of fractures. These treatments are only available from GPs or consultants and are only prescribed for those people with a low bone density, fractures or risk factors for osteoporosis. They are not routinely given as a preventative measure. They are effective in treating osteoporosis in people with low levels of either oestrogen or testosterone and so are potentially useful in people who, for medical reasons, are no longer able to take oestrogen.
Factors that can help to maintain healthy bones are a well balanced diet with adequate calcium rich foods, regular weight bearing exercise, avoiding smoking and keeping alcohol consumption to within the Governments recommended limits.
The Gender Trust
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Further information about bone health and osteoporosis is available from the NOS, Camerton, Bath, BA2 0PJ. Telephone 01761 471771 or the NOS Helpline - 0845 450 0230.