Bone Loss

Osteoporosis Bone is made up of calcium and protein. There are two types of bone -- compact and spongy bone. Each bone in the body contains some of each type. Compact bone appears hard and solid, and is found on the outside of bones. Spongy bone is found on the inside of bones and is filled with holes.
Bone is constantly undergoing change with old bone broken down and new bone formed every day. When young, more bone is formed than is broken down with the peak bone mass reached by 30 years of age. After that, more bone is broken down than is formed. This small amount of bone loss continues for the rest of life.
Bone loss increases after the menopause when the ovaries stop producing oestrogen, which protects against bone loss.
A little bit of bone loss does not usually cause problems. However, excessive bone loss results in osteoporosis which is characterised by compromised bone strength resulting in an increased risk of fracture. Although the bones are still of the same size, the outside walls of compact bone becomes thinner and the holes in spongy bone become larger, thereby weakening the bone considerably.
The condition of a woman's skeleton depends on two factors -- the amount of bone attained before the menopause and the rate of bone loss thereafter.
The initial signs of osteoporosis are seen in bones that have a lot of spongy bone i.e. spine, hip and wrist.
The symptoms of osteoporosis do not appear until a lot of bone is lost, thus explaining why it is called a silent disease. They include backache, pain, decrease in height and slight back curvature. When there is a fracture, there will be pain, tenderness and even deformity.
Osteoporosis is measured using bone density. The World Health Organisation has defined the following categories using the T Score, which is the bone density of an individual expressed in standard deviations compared to young adults:
• Normal bone density is less than one standard deviation (T-1) below the young adult mean.
• Osteopenia is one to 1.25 (T-1 to T-2.5) below the young adult mean.
• Osteoporosis is more than 2.5 standard deviations (>T-2.5) below the young adult mean.
Another term used in bone density measurement is the Z score, which is the individual's bone density expressed in standard deviation units compared to an age matched population.
Osteoporotic fractures are increasingly common in all Asian countries. The impact of these fractures is tremendous. It affects the physical, psychosocial and financial aspects of a patient's life and that of the family and community. There is a mortality risk of about 25% in the first year. The quality of life is also substantially affected. About 10% will be bedridden and 25% wheel chair bound. In addition, there is chronic disabling pain with effects on the patient's emotional and mental lives.
Women are at greater risk of osteoporosis than men because their bones are smaller and lighter. The factors that increase risk of osteoporosis include:
Ethnicity. Caucasian and Asian women are at greater risk.
Family history.
Slender build.
Natural menopause because the protective effect of oestrogens on bone is lost. Menopause is the biggest culprit in the process of bone loss.
Surgical removal of the ovaries causes a sudden decrease in oestrogen resulting in rapid bone loss unless it is replaced.
Low calcium diet. Calcium slows the rate of bone loss. The recommended daily requirement is 1,000g before the menopause and 1,500g after the menopause.
Lack of exercise. Just as muscles become stronger with exercise, so do bones. Exercise increases bone mass before the menopause and slows down bone loss after the menopause.
Eating disorders like anorexia nervosa and bulimia.
Tobacco and alcohol use.
Medicines like diuretics, steroids and anticonvulsants.


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