Osteoporosis can be divided into two types: primary and secondary osteoporosis. Primary osteoporosis is the more common of the two. Secondary osteoporosis is usually the result of an identifiable agent or disease process that causes the bone loss.
Although the exact cause of primary osteoporosis is not always clear, a number of risk factors are known to increase the chances of developing this disease.
Remember - an individual may have these risk factors and not develop osteoporosis. Conversely, many people may have no apparent risk factors and develop osteoporotic fractures.
are many secondary causes for osteoporosis. Your doctor will mostly be able to
detect these on the history you provide, or on the initial examination you
more common associated secondary causes of osteoporosis include:
(A) Decreased bone strength
(i) Genetic Factors
history of osteoporosis
Asian and Mixed-race origin
(ii) Lifestyle factors
exercise plus low energy intake
(iv) Aging Factors
menopause (before age 45)
(bone building cell) incompetence
calcium balance resulting in overproduction of parathyroid hormone
(B) Increased propensity to fall
and balance disorders*
* Increased by alcohol and drugs like
sedatives, anti-depressants, antihypertensive drugs and anti-diabetes agents.
Gender, Age and Race
The peak bone mass of women, which is
reached at 25-30 years, is usually about 10-25% less than that of men. After
peak bone mass is reached, bone mass gradually declines in both women and men.
Because of the rapid bone loss during the menopause, osteoporosis occurs more
frequently in women than in men, who have no well-defined “andropause.” Men also
lose sex hormones (testosterone) at a much slower rate.
Although osteoporosis is not a normal
part of aging, the likelihood of developing this disease and associated
fractures become greater, the longer you live.
South African White, Asian and Coloured
populations are at higher risk to develop osteoporosis than Blacks and
researchers are currently studying the reasons for this occurrence.
Genetic factors play an important role
in achieving adult peak bone mass. This is apparent in females those mothers
suffer from spinal osteoporosis and tend to have lower bone densities.
Calcium intake, exercise, hormonal
factors and general health can however, influence peak bone mass.
Short, small framed individuals with
low body weight have less bone to lose than larger, big boned women. Fat tissue
is an important source of oestrogen production – petite women often have lower
blood levels of this bone-protective hormone.
The female sex hormone oestrogen
protects against bone loss. A premature menopause (before age 45), whether
spontaneous or surgically induced, noticeably increases the risk of
Not breastfeeding also appears to incur
additional risk, whereas pregnancy – with its accompanying high levels of
oestrogen– actually protects against bone loss. A rare form of pregnancy-induced
osteoporosis is however, well documented.
A decrease in testosterone levels of
men can also result in bone loss and osteoporotic fractures. Up to 30% of men
with osteoporosis have low testosterone levels.
A variety of nutritional factors influence
bone health. Therefore, a balanced diet containing adequate calories, minerals,
vitamins and other nutrients is required to build and maintain strong bones.
Sufficient calories, protein and vitamin C are required for normal collagen
Excessive phosphorous, protein and salt
intake may enhance the excretion of calcium in the urine.
Caffeine has still to be proven harmful
Calcium is probably the most important
nutrient needed for a healthy skeleton – especially in the elderly, children
and pregnant or lactating women.
Calcium is important for bone, muscle,
heart, nerve and blood cells to function normally. Since we lose calcium in
urine and stools every day, it is therefore important to balance this loss with
an adequate intake of calcium. If the calcium loss exceeds the intake, calcium
gets released from bones and a longstanding depletion can result in decreased
Lack of exercise
Mechanical muscle-pull on bone is the
only physiological way to stimulate bone formation. Immobilisation causes a
dramatic decrease in bone tissue and 20-40% of bone mass can be lost within a two-year
period. Weight-bearing exercises like walking, jogging, dancing etc. are
important to prevent bone loss.
Over-training in both men and women can
also lead to bone loss.
Studies have shown that exceeding the
intake of one alcoholic drink per day in women and two per day in men can lead
to osteoporosis. Chronic alcoholism is associated with significant bone-loss in
nearly 50% of cases and alcohol has a direct toxic effect on bone.
Women who smoke tend to have lower
blood levels of oestrogen, a lower body mass and tend to go through an earlier
menopause than non-smokers. Bone mass in smokers is generally 15-25% lower than
The long-term use (more than six
months) of glucocorticoids (e.g. cortisone used for treating asthma, eczema,
arthritis, etc.) is an important cause of osteoporosis.
Other medications known to influence
bone formation negatively include anti-epileptic drugs, certain diuretics,
anti-coagulants, immuno-suppressive drugs and aluminium-containing antacids.
Patients on thyroid hormone replacement
therapy should have their hormone levels checked regularly, since excess
thyroid hormone can also result in bone loss.
Symptoms of osteoporosis
Reviewed by Dr Gareth
Lorge FCP (SA), Specialist Physician in
private practice, Netcare Rosebank Hospital, February 2015.
Previously reviewed by
Tereza Hough, CEO, National Osteoporosis Foundation of South Africa, 2010.