Osteopaenia is a decrease in the mineral density of bone. This may occur as part of normal aging, or may be a precursor of osteoporosis. It is more common in post-menopausal women, and in young female athletes.
Osteo porosis is measured by bone densitometry: a T-score is calculated for an individual patient, and a Z-score is a comparison of a patient's score with that of other similar aged patients.
Osteo paenia is a T-score of -1 to -2.5, and definite osteoporosis is a T-score of -2.5 and lower.
A specific form of osteopaenia can occur in newborn babies, especially if they are pre-term.
Osteopaenia is seldom diagnosed, due to its lack of symptoms, but by inference, must be very common. Osteo porosis is very common, affecting 20 percent of women over the age of 50. As full blown osteoporosis takes time to develop, all of these women must have been osteopaenic at some stage on their way to becoming osteoporotic.
- Lifestyle factors:
- Excess alcohol,
- Lack of exercise, and prolonged immobility,
- Long-term use of steroids, and
- Dietary - inadequate intake of minerals.
- Female athletes with lower body fat are more at risk (there is often an association with amenorrhoea and eating disorders in these women).
- Oestrogen deficiency - for instance, post-menopause.
All of the above factors contribute to poor mineral absorption and/or incorporation into bone structure. Calcium and phosphate are the two main minerals involved in bone metabolism.
Osteopaenia causes no symptoms. Problems usually arise only once it has progressed to osteoporosis, and fractures occur.
Screening and diagnosis
Patients at risk should be screened for bone mineral density by DXA testing. This test uses technology similar to X-rays, but with minimal radiation exposure. (Despite this, it is not advised during pregnancy). Sites recommended for DXA tests are the lumbar spine and the femur, especially the neck of the femur (upper leg bone).
Blood tests will be indicated if menopause, thyroid or parathyroid disorders are suspected.
The first step is to manipulate any risk factors. This can be done by, for instance, stopping smoking, increasing exercise, correcting dietary deficiencies and encouraging supplements such as calcium and vitamin D.
Medical disorders like hyperparathyroidism will need referral to the appropriate specialist for full investigation and management.
Post-menopausal women will benefit from oestrogen replacement therapy, where possible: each woman is individually assessed for this.
If possible, steroid use should be stopped or reduced. If the patient has a chronic underlying condition, the use of other medication should be investigated.
Annual DXA testing is recommended to assess the response to treatment. If there is no response, or a worsening to develop osteoporosis, a protocol for osteoporosis therapy may need to be followed.
(Dr A G Hall)