Osteoporosis

Osteoporosis occurs when your bones become brittle and are more easily fractured. It is more common in women, particularly after menopause when oestrogen levels are low, as oestrogen helps maintain bone mass.

Causes

Normally your bones undergo a constant cycle of remodelling. The two stages of this remodelling are bone resorption, in which bone is broken down, and bone formation, in which it is created. The two are normally kept in balance, but in osteoporosis the breakdown of bone occurs faster than the creation of it. This imbalance in the cycle of bone remodelling occurs as a result of menopause and ageing, as well as from a range of conditions.

Visual appearance of osteoporotic bone.  

Signs and symptoms

There are usually no obvious symptoms of osteoporosis until it causes a fracture, which is why it is sometimes referred to as a silent disease. Collapse of the vertebrae in the spine is the hallmark of osteoporosis.

Methods for diagnosis

Bone density testing

The following bone density tests can be used to detect a loss of bone strength in people who might not have symptoms, or to monitor the effects of treatment for bone disease:

Dual-energy X-ray absorptiometry

Dual-energy X-ray absorptiometry (DEXA) is a special type of scan that uses low-dose X-rays. Depending on the size of the bone being measured, you may need to lie down in a large machine.

Standard measurements are usually taken from the spine and hip, and a measurement of bone density is given. The readings are usually given in three ranges - normal for age, mildly lower than expected for your age (osteopaenia), or significantly lower than expected for your age (osteoporosis).

DEXA imaging. 

Quantitative computerised tomography

Quantitative computerised tomography can determine bone density of the spine, but it is not regularly used, as it uses a higher radiation dose than DEXA and is more expensive.

Ultrasound

Ultrasound is sometimes used to measure bone density in the heel bone when DEXA is not available.

Types of treatment

Depending on your circumstances, your doctor will recommend the most suitable osteoporosis treatment for you. This may depend on the underlying cause, whether you are male or female and any side effects you may have had to previous treatment. If you are female, your menopausal status will be taken into account.

Lifestyle

Modification of lifestyle factors is recommended to improve treatment outcomes. Quitting smoking, reducing your alcohol intake, meeting your recommended daily intake of calcium, maintaining a healthy body weight and exercising regularly can all help slow the progress of osteoporosis.

Bisphosphonates

Bisphosphonates are a type of antiresorptive medication, which means that they block the breakdown of bone. They include alendronate, ibandronate, risedronate and zoledronic acid.

Other antiresorptive medications

Raloxifene

Raloxifene is a selective oestrogen receptor modulator (SERM), which can be used in postmenopausal women to help prevent or treat osteoporosis.

Denosumab

Denosumab reduces bone resorption by blocking the activation and function of cells called osteoclasts, which normally resorb bone.

Calcitonin

Calcitonin is a hormone that is produced by the thyroid gland. For the treatment of osteoporosis, it is administered by injection or a nasal spray. It is usually only used for postmenopausal women who do not respond to other treatment. It is not widely used any more, due to other more effective medications.

Hormone replacement therapy

Hormone replacement therapy (HRT) is not recommended as a main treatment of osteoporosis by authorities in Australia, which is contrary to international menopause recommendations. HRT programs contain oestrogen, which can help to reduce bone loss and prevent fractures in postmenopausal women. The response to treatment is dose-dependent and even small doses can have a beneficial effect in preserving bone density.

Anabolic medications

Anabolic medications, such as teriparatide, increase bone formation. They build bone, as opposed to antiresorptive medications, which prevent it from being broken down.

Vitamins and minerals

Your doctor will assess your individual need for calcium and vitamin D supplements. Calcium is only required if your dietary intake is not adequate for your age and menopausal status. Vitamin D levels can be measured with a blood test and if low, a daily oral dose of vitamin D may be recommended.

Potential complications

The main complications of osteoporosis are bone fractures, particularly of the hip and spine. Hip fractures may result from a fall and often require surgery. Hip fractures can lead to ongoing disability and potentially death.

Spinal fractures are common and can occur even without injury. They can accumulate over time, causing you to hunch over and become shorter (known as kyphosis).

Treatment options can cause a wide range of side effects, such as heartburn and gastritis, pain in bones and joints, and rarely, damage to the jaw bone.

However, your doctor will usually closely monitor you while you are on these treatments to detect any side effects. If any are present, your dose or medication can be changed. Talk to your doctor or pharmacist to find out about the possible side effects of the medications you are currently taking.

Prognosis

Treatment helps slow the progression of osteoporosis. Monitoring how you respond to treatment takes the form of a DEXA scan every one to two years. Treatment outcomes vary from person to person, but in general, the earlier you start treatment the better.

Prevention

If you are at high risk of developing osteoporosis, treatment can help prevent the onset of disease. Not smoking or drinking to excess, meeting your recommended daily intake of calcium, maintaining a healthy body weight and exercising regularly all help lower your risk.