What is postmenopausal osteoporosis?

Osteoporosis is caused by loss of bone mass, making bones more brittle and more prone to fractures. Maximal bone density is achieved in the third decade of life and is followed by a gradual age-related bone loss. The rate of bone loss increases following the menopause and women are therefore at much greater risk of osteoporosis than men.

In osteopenia the bone density is below average but not low enough to be classed as osteoporosis. 

The three most common fracture sites are the wrist, the vertebral spine, and the hip (proximal femur). 

Proximal femur (hip) fractures are the most serious. About 10% will die within one month of injury and about one-third within 12 months. Furthermore, of those who survive this injury, 50% do not regain their pre-injury mobility.

What are the symptoms?

Osteoprosis is asymptomatic and can only be diagnosed using a bone density (DEXA) scan, which uses low levels of X-ray and is quick and safe.

DEXA scans are also useful in monitoring the treatment of osteoporosis.

It is not cost-effective to screen the whole population for osteoporosis but those women who are at increased risk should have a DEXA scan.

Risk factors include:

• Family History of Osteoporosis
• Previous fracture
• Overactive Thyroid – Thyrotoxicosis
• Premature menopause
• History of anorexia or exercise-related amenorrhea
• Low weight (BMI less than 19)
• Long-term steroid use
• Malabsorption such as Coeliac or Crohn’s disease
• Excess consumption, of alcohol, caffeine
• Smoking

How can it be prevented and treated?

HRT
HRT (Hormone Replacement Therapy) is the first line treatment for the prevention and treatment of postmenopausal osteoporosis. Oestrogen replacement can prevent bone loss and has been shown to reduce the incidence of fractures.

HRT has further advantages; it can alleviate symptoms of the menopause which includes hot flushes, night sweats, poor sleep, tiredness, mood swings and forgetfulness, leading to an improved quality of life.

Women who have a premature menopause (before the age of 40), also known as premature ovarian insufficiency (POI), are at increased risk of osteoporosis because they will start losing bone density at a younger age. It is especially important for these women to be offered HRT to protect against osteoporosis as well as the other long-term effects of this condition including heart disease and possibly dementia. HRT will also prevent the symptoms of the menopause which can be particularly distressing in these young women.

Non-Hormonal Treatment

Lifestyle
A healthy lifestyle with regular exercise, and a healthy diet with adequate calcium and vitamin D intake are important in maintaining bone density and help to reduce the risk of developing osteoporosis but have very little impact on established osteoporosis.

SERMS
Selective Estrogen Receptor Modulators (SERMS) such as Raloxifene are drugs that act as an oestrogen in some tissues such as bones and as an anti-oestrogen in other tissues such as the breast. They are less effective than oestrogen in preventing osteoporosis; they have been shown to reduce the risk of vertebral but not hip fractures and do not alleviate menopausal symptoms.

Bisphosphonates
These drugs can be used for the treatment of osteoporosis and have been shown to reduce the incidence of osteoporotic fractures. However, prolonged use of Bisphosphonates may result in fragility fractures in the femur and osteonecrosis in the jaw, particularly following dental treatment such as dental extraction.

Bisphosphonates can persist in bones for many years and are therefore not recommended in younger post-menopausal women.

Denosumab
Denosumab can also increase bone density and reduce the risk of fractures at the spine and hip but has similar side effects as bisphosphonates, with osteonecrosis and increased fragility fractures of the femur. Moreover, this drug can impact on the immune system and is associated with an increase in risk of infections.

Conclusion

HRT is the treatment of choice for the prevention and treatment of osteoporosis in women, with the added benefit that it will control menopausal symptoms. However, concerns about the safety of HRT largely based on the flawed HRT studies persist.

Recent analysis of the results from the WHI studies agree with other published work which indicate that HRT can reduce the risk of heart disease. Oestrogen given alone (unopposed oestrogen) does not increase the risk of breast cancer, but combined HRT (oestrogen plus a progestogen) may lead to a small increase in breast cancer. However, it is worth remembering that this risk is very small, and smaller than the risk of breast cancer associated with smoking, obesity or consuming more than 2 units of alcohol per day  Patients can be reassured that transdermal HRT such as patches gels or spray will not increase the risk of thrombosis.

The benefits of HRT including the prevention of osteoporosis outweigh the risk.