Osteopenia: An Overview
Osteopenia is a condition where the bone density is lower than normal but not so low that it meets the criteria for osteoporosis. The term is derived from the Greek words osteo, meaning bone and penia, meaning poverty. If taken literally, osteopenia means "poor bone".
Osteopenia is a loss of mineral density within bone tissue. It represents part of a continuum with osteoporosis; the two conditions are linked although not everyone with osteopenia will develop osteoporosis.
|Normal||Bone mineral density (BMD) greater than 1 standard deviation below the mean for young adults|
|Osteopenia||BMD between 1-2.5 standard deviation below the mean for young adults|
|Osteoporosis||BMD more than 2.5 standard deviation below the mean for young adults|
|Severe osteoporosis||BMD more than 2.5 standard deviation below the mean for young adults plus one or more fragility fractures.|
Table 1 Diagnostic criteria for osteoporosis
Table 1 describes the diagnostic criteria for osteoporosis (3) as developed by the World Health Organisation (WHO) and illustrates where osteopenia fits into the continuum.
Osteopenia is determined based on the findings of bone mineral density (BMD) testing. A special machine called a DXA machine (DXA stands for dual energy x-ray absorptiometry) is used to measure the amount of bone mineral in a certain area. Testing can be performed on your forearm, wrist, hand, hip, spine, or foot. BMD tests are important tools in the arsenal of bone medicine, and they are commonly ordered by doctors.
The findings of a BMD test are classified according to comparison with
average values of healthy subjects which provides a T-score. A T-score,
between -1.1 and -2.4 identifies osteopenia. The lower the T-score (higher
the negative number), the higher the risk for bone fracture.
Symptoms of Osteopenia
Osteopenia has been described as a "silent" condition (4). There are no outward signs or symptoms, although certain risk factors and precursors can be identified.
Risk Factors which may influence loss of BMD
Most cases of osteopenia are seen in post menopausal women; this is due to the influence of estrogen on bone cells (i.e. when estrogen levels fall osteoclasts have a prolonged lifespan so more mineral is desorbed than absorbed into the bone). Peak BMD is reached around the age of 30; as we age it steadily decreases. Other risk factors include: a personal or family history, low body weight, a sedentary lifestyle, diet, smoking and other medical conditions.
Individuals with risk factors should consider screening for osteopenia/osteoporosis. The National Osteoporosis Foundation (5) lists the following as recommendations for undergoing DXA testing:
- Women: postmenopausal and under age 65 with risk factors for osteoporosis, over 65 whether or not there are risk factors present
- Men: age 50-70 with risk factors for osteoporosis, over age 70 whether or not there are risk factors present
- Anyone over age 50 after a bone break
If a patient gets shorter with age, the doctor will probably order a bone mineral density test. Other reasons your doctor may give you a BMD test:
- Long-term use of certain medications including steroids for breast cancer, prostate cancer, aromatase inhibitors, cortisone, and hormone replacement therapy
- Hyperthyroidism or Hyperparathyroidism
- Frailty syndrome
- Fracture or bone loss in spine
- Chronic back pain that causes the doctor to suspect a fracture
Prevalence of Osteopenia
Because there are no obvious symptoms of osteopenia, assessing how many people have this condition is difficult as many cases may go undiagnosed. A study in 2007 stated that approximately 33.6 million adult Americans were osteopenic in 2002; it went on to estimate that this figure may rise to 47.5 million by 2020. (Note that some people think osteopenia should not be treated at all.)
Treatment of Osteopenia
Appropriate treatment of osteopenia might prevent osteoporosis.
Drugs that stop bone re-absorption and hormone replacement therapy have been proven to help for osteoporosis but there is little long term evidence as to their efficacy in osteopenia. The National Osteoporosis Foundation guidelines for post-menopausal women and men past age 50 recommend that people with T-scores between -1 and -2.5 should consider taking an osteoporosis medication. Whether these medications really help osteopenia patients is a matter of some dispute.
- People with T-scores of -1 and above (normal bone density) do not need to take an osteoporosis medication.
- People with osteopenia (T-scores between -1 and -2.5) should ask their doctors if they shoud take an osteoporosis medication. Other risk factors come into account.
- Patients that have T-scores at or below -2.5 (this is the technical criteria for osteoporosis) should probably be taking medicine. The doctor will determine the best course for each patient.
A recent development which may assist doctors and patients to decide if osteoporosis medication is necessary is a tool called "Absolute Fracture Risk Assessment" which estimates a person’s chance of breaking a bone over a period of 10 years.
Regardless of whether medication is used, other interventions should be implemented in patients with osteopenia. Ensuring that there is sufficient calcium and vitamin D in the diet, lifestyle modifications such as stopping smoking and getting regular resistance exercise will help to maintain bone mineral density.
In 2012 NASA announced a method of detecting the early stages of bone loss. The technique involves analysis of calcium isotopes in the bone. The analysis does not subject the patient to radiation. It may be years before this method goes mainstream, if it ever does.
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Last updated: Oct 7, 2012