There are many causes of osteoporosis. Not only do bones lose density with age, medications used to treat breast cancer, arthritis, asthma, Crohn's disease and Addison's disease can also lower bone density. Some illnesses such as hyperthyroidism, hypopituaritism and eating disorders also cause bones to lose strength. You will find information on all of these causes of lowered bone density, along with the role of oestrogen in bone density.
Osteoporosis is a condition in which bones become thinner, or lose 'bone mineral density'. This leads to an increased risk for fractures. Osteoporosis is more common in women, especially after menopause. However, a number of conditions may be associated with a decrease in bone density.
Ageing reduces bone strength because more bone is broken down than can be made – everyone develops osteoporosis if they live long enough.
Excessive alcohol intake increases the risk of developing osteoporosis.
Women with breast cancer have an increased risk of developing osteoporosis because of the treatments used and their effect on oestrogen levels.
A lack of calcium affects bone strength and the muscles that support bones, so adequate intake is essential.
A steroid replacement hormone including:
Long-term use (more than 2 months) of oral corticosteroid type medications, with doses of more than 5-7.5mg of prednisolone per day, increases the risk of developing osteoporosis by reducing bone formation and bone density
If other risk factors for osteoporosis (such as being postmenopausal) are present, the effect on bones will be more severe
Corticosteroid therapy may be prescribed for a variety of conditions such as:
Eating disorders in early adolescence, when the skeleton is in the process of growing, severely reduce the potential to achieve peak bone mass and this can lead to osteoporosis in women as young as the early 20s. If you develop an eating disorder after the process of skeletal growth has been completed you still risk reducing your bone mineral density.
You are at increased risk of osteoporosis if you have a family member with osteoporosis, especially a parent or sibling who has had a hip fracture.
A drop in oestrogen can cause a loss in bone strength and this means bone density may be decreased:
Illness or diseases, and sometimes their treatments, can affect bone strength including:
Lack of physical activity reduces bone and muscle strength, which increases the risk of fractures and falls.
Rheumatoid arthritis is an inflammatory disorder that may affect tissues and organs, but principally attacks flexible joints (i.e. elbows and knees). It is a condition affecting approximately 1% of the population, with women affected around 3 times more than men.
If prednisolone is prescribed as part of the medical treatment, this can also lead to the development of osteoporosis, especially in bones adjacent to the affected joints.
Smoking, especially how much you smoke, can cause:
Low vitamin D can reduce the body's ability to absorb the calcium required for bone strength.
The sex hormone oestrogen plays a vital role in the development of bones.
** Currently under review **
This web page is designed to be informative and educational. It is not intended to provide specific medical advice or replace advice from your health practitioner. The information above is based on current medical knowledge, evidence and practice as at December 2013.