Boosting bone density
By DR MILTON LUM
Taking vitamins, minerals and hormonal therapy are some of the ways to prevent brittle bones.
THE treatment goal in the management of osteoporosis is to increase bone density. The medicines available include vitamins, minerals, calcitriol, hormone therapy (HT), selective oestrogen receptor modulators (SERMS), bisphosphonates and recombinant parathyroid hormone.
A high calcium intake plays a crucial role as an adjunct to the other treatment options. Calcium intake has a synergistic bone protective effect along with hormone therapay in post-menopausal women, allowing a doubling or even tripling of the effect of the therapy.
Supplements
Hormones by themselves do not provide substances to form bone – they need to come from the diet. As such, the first step is to ensure that an adequate amount of calcium and vitamin is consumed daily.
Most people, particularly women, should get sufficient vitamins and minerals in their diet. A recent study found that 49% of post-menopausal Malaysian women have vitamin D levels below the normal range, despite the fact the sun is shining throughout the year. This, together with lower rates of calcium absorption and increased bone loss in post-menopausal women, contribute to the development of osteoporosis.
The daily requirement of vitamin D is 400 IU. If one is never in the sun, 800 IU of vitamin D is recommended. This has been shown to reduce fracture in the elderly who are vitamin D deficient. If calcium cannot be obtained from the diet, a calcium supplement may be required to attain the recommended daily requirement of 1,000 to 1,500mg of elemental calcium.
The risk of urinary tract stones is not increased if the calcium consumed does not exceed 1,500mg per day. It is advisable to drink plenty of water. Calcium should not be taken with fibre or iron supplements.
Calcitriol is a synthetic form of vitamin D used to treat osteoporosis. It is one of the most important active metabolites of vitamin D, which is needed for calcium absorption. Calcitriol increases intestinal calcium absorption, regulates bone mineralisation and the production of bone proteins. It prevents bone loss and increases bone mass thereby reducing fractures.
Alfacalcidol is converted in the liver to a metabolite of vitamin D3. It has a rapid onset of action and is safe and effective. It increases bone mineral density, improves biochemical markers and is effective in preventing osteoporotic fractures in the spine and those with mild to moderate osteoporosis.
Hormones
The oestrogen levels in a post-menopausal woman are about 10% that in the reproductive age group and progesterone is almost absent. Post-menopausal oestrogen is produced by the adrenal glands and fat.
Hormone therapy usually involves treatment with either oestrogen alone or in combination with progestogen to help compensate for the decrease in natural hormones. Its use only doubles the oestrogen level of a post-menopausal woman. Hence, even with hormone therapy, the oestrogen and progesterone levels of a post-menopausal woman do not reach the natural levels of a pre-menopausal woman.
The medicines used in hormone therapy are similar in certain aspects yet different in others, with different modes of action, side effects and adverse events. Hormone therapy is the only effective method for the management of menopausal symptoms..
The long-term use of hormone therapy, like all other medicines, has risks as well as benefits. It is beneficial in the prevention and treatment of osteoporosis but it is not the first line medicine as alternatives are available.
When hormone therapy is used for the treatment of menopausal symptoms, it will also decrease bone loss and prevent osteoporosis. Hence, during its intake, the alternatives need not be taken. Hormone therapy is also recommended in women who have premature menopause, that is, menopause below 40 years.
Hormone therapy is an effective method to prevent post-menopausal osteoporosis. It increases bone density at the spine, hip and peripheral sites, and reduces the risk of fractures. The beneficial effects of hormone therapy have been consistently reported in many studies. The potential risks must be weighed against the benefits.
As breast tissue is sensitive to hormones, there has been concern about breast cancer risk among hormone therapy users. Short-term use of less than five years does not appear to increase the risk of breast cancer.
There is some evidence that long-term hormone therapy use may be associated with a small increase in the incidence of breast cancer (with best evidence for combination of oestrogen and progestogen).
The Collaborative Group on Hormonal Factors in Breast Cancer, in an analysis of over 90% of breast cancer studies worldwide, estimate that there are 45 cases of breast cancer in 1,000 women at aged 50 in non-hormone therapy users.
It is estimated five years of hormone therapy use will result in two extra cases per 1,000 users; after 10 years of use, six extra cases per 1,000 users; and after 15 years of use, 12 extra cases per 1,000 users. The extra risk of developing breast cancer on hormone therapy does not persist beyond about five years after stopping its use.
There is good evidence that hormone therapy increases the risk of blood clots (venous thromboembolism) from one in 10,000 people a year to three. Most people who get a blood clot make a complete recovery with treatment. There is fair evidence that hormone therapy use is associated with a small increase in stroke incidence due mainly to an increase in thromboembolic stroke.
Unopposed oestrogen increases the development of endometrial hyperplasia and the risk of endometrial cancer. The addition of progestogen reduces the risk of endometrial cancer.
Oestrogen-only products are prescribed for women who have had a hysterectomy. All other women on hormone therapy will be prescribed an oestrogen-progestogen combination.
Prior to the commencement of hormone therapy, one needs to be assessed by the doctor particularly for conditions which would make hormone therapy unsuitable: current pregnancy, hormone dependent cancers, endometrium, venous thromboembolic disease, pulmonary embolism, severe liver disease, undiagnosed breast lump and uninvestigated abnormal vaginal bleeding.
Oestrogen is usually taken in hormone therapy unless there are contraindications. Various types of progestogens are added for endometrial protection in women with an intact uterus.
Tibolone is a synthetic steroid with mixed oestrogenic, progestogenic and androgenic actions. It is a prescribed for postmenopausal women and has to be taken continuously. It is used to treat vasomotor, psychological and libido problems, and also possesses bone protection.
Hormone therapy should be used under medical supervision. Long term use, such as more than five years, require close monitoring and a regular evaluation (at least annually).
· Dr Milton Lum is a member of the board of Medical Defence
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· This article was published in the Star online 29 Apr 2009
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