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Young People Get Osteoporosis Too 

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related pages:
Fracture Risk Calculator
percentage changes in BMD calculator
 
DEXA Scanning
Dual Energy X-ray Absortiometry, or DEXA scanning, is currently the most widely used method to measure bone mineral density. For the test, a patient lies down on an examining table, and the scanner rapidly directs x-ray energy from two different sources towards the bone being examined in an alternating fashion at a set frequency. The mineral density of the patient's bone weakens, or prolongs the transmission of these two sources of x-ray energy through a filter onto a counter in a degree related to the amount of bone mass present. The greater the bone mineral density, the greater the signal picked up by the photon counter. The use of the two different x-ray energy sources rather than more traditional radioisotope studies (such that would be used for a bone scan) greatly improves the precision and accuracy of the measurements.

Bone-mineral density (BMD)
Bone mineral density is a measured calculation of the true mass of bone. The absolute amount of bone as measured by bone mineral density (BMD) generally correlates with bone strength and its ability to bear weight. By measuring BMD, it is possible to predict fracture risk in the same manner that measuring blood pressure can help predict the risk of stroke. It is important to remember that BMD cannot predict the certainty of developing a fracture; it can only predict risk.

The World Health Organization has used BMD to define specific diagnostic categories. It should be noted that all "normal" values of BMD are based on Caucasian data. It is well documented that there is significant variation in BMD between ethnic groups. For example, African Americans in general have a greater BMD as compared to Caucasians of the same age and weight. Interpretation of results must take this difference into account

The bone densitometry test determines the bone mineral density (BMD). Your BMD is compared to two norms - healthy young adults (your T-score) and age-matched (your Z-score).

 

First, your BMD result is compared with the BMD results from healthy 25- to 35-year-old adults of your same sex and ethnicity. The standard deviation (SD) is the difference between your BMD and that of the healthy young adults. This result is your T-score. Positive T-scores indicate the bone is stronger than normal; negative T-scores indicate the bone is weaker than normal.    

 

In general, the risk for bone fracture doubles with every SD below normal. Thus, a person with a BMD of 1 SD below normal (T-score of -1) has twice the risk for bone fracture as a person with a normal BMD. A person with a T-score of -2 has four times the risk for bone fracture as a person with a normal BMD. When this information is known, people with a high risk for bone fracture can be treated with the goal of preventing future fractures.     

T-score

The T-score shows the amount of bone you have compared to a young adult (at the age of 35) of the same gender with peak bone mass  T-scores are based on a statistical measure called the standard deviation, which reflects differences from the average score.

T-score statistically speaking what it means diagnosis
higher than -1 your bone mass is within 1 standard deviation of the avg for a 35 year old healthy young adult women your bone mass and your risk of fractures are avg or better adequate bone density
between -1 and -2.5 your bone mass is between 1 and 2.5 standard deviations lower than the avg for a 35 year old healthy young adult women your bone mass is lower than normal, and your fracture risk is approximately twice as high as avg osteopenia
less than -2.5 your bone mass is lower than the avg for a 35 year old healthy young adult women by more than 2.5 standard deviations your bone mass is very low--lower than 99% of healthy young adult women, your risk for fractures is approximately three times higher than avg osteoporosis
-2.5 and below with presence of fracture very low bone density very high risk of further fracture severe osteoporosis

The Z-score
Z-scores are calculated in the same way, but the comparisons are made to someone of your age, sex, race, height, and weight.  Physicians may also measure a patient’s Z-score with a bone mineral density test. The Z-score is not used to confirm a diagnosis of osteoporosis because a favorable BMD measurement (compared to the average BMD measurement for the patient’s age group) does not mean the patient is not at risk for osteoporosis.

 
Z-score statistically speaking what that means
higher than -1 your bone mass is within 1 standard deviation of the avg for women your age, or better. your bone mass is within or above the normal range for women your age
between -1 and -2.5 your bone mass is between 1 and 2.5 standard deviations lower than the avg for women your age your bone mass is lower than avg for your age; compared to your peers, you're in the lowest 1 to 14%
less than -2.5 your bone mass is lower by more than 2.5 standard deviations than the avg for women your age your bone mass is much lower than avg--lower than 99% of women your age.
 
Osteopenia is not a disease, but a term that describes low bone density.  While osteopenia is not considered a disease, being diagnosed with it requires further monitoring. Preventive measures should be taken since osteoporosis may develop if bone density loss increases
Severe Osteoporosis
According to the WHO (World Health Organization) Severe osteoporosis is considered to be present when the value for bone mineral content is more than 2.5 SDs below the mean for young adults and there is at least one so-called fragility fracture (a fracture assumed to be associated with osteoporosis because it occurred as a result of slight trauma).

The relationship between BMD and fracture risk
In subjects with low bone mass, there is a 2 to 3 fold increase in the incidence of spinal fractures. In subjects with a BMD in the osteoporosis range, there is approximately a 5 times increase in the occurrence of fractures

How do doctors interpret the test results and decide who is a candidate for treatment?
A DEXA scan report compares the patient's bone mineral density values with those of young normal patient (T score) and with age matched normal patient (Z score). By comparing a patient's bone density against there peers, a low score indicates there may be a reason other than age related bone loss.

Patients risk factors for osteoporosis that should play a part in the decision to begin treatment include: a maternal history of a hip fracture, any previous fracture after the age of fifty, tall height at age of 25, poor health, some sedatives and anticonvulsant drugs, and the inability to rise from a chair without the use of the arms.

National Osteoporosis Foundation's guidelines recommend that the following people should take or consider bisphosphonates:
  • Women with a below-normal bone density of 2.5 SD or greater and who have no history of fractures should take bisphosphonates.
     
  • Women with below-normal bone density 1 SD or more and have a history of fractures should consider bisphosphonates.

How often should DEXA scans be repeated to monitor treatment?
Monitoring osteoporosis treatment using DXA scan is a controversial issue. Some doctors recommend DXA scanning at 1 to 2 year intervals to monitor changes in bone density during treatment. But recent scientific evidence questions the usefulness of such interval monitoring. The American Medical Association and other reputable medical organizations have determined that repeat DXA scans is NOT helpful in monitoring osteoporosis treatment or prevention.

The reasons are:

  • Bone density changes so slowly with treatment that the changes are smaller than the measurement error of the machine. In other words, repeat DXA scans cannot distinguish between a real increase in bone density due to treatment or a mere variation in measurement from the machine itself.

     
  • Whereas the real purpose of osteoporosis treatment is to decrease future bone fractures, there is no good correlation between increases in bone density as measured by DXA with decreases in fracture risks with treatment. For example, alendronate has been shown to decrease fracture risk by 50%, but only to increase bone density by a few percent.

     
  • DXA measurement taken during treatment will not help the doctor plan or modify treatment. For example, even if the DXA scan shows continued deterioration in bone density during treatment, there is not yet research data demonstrating that changing a medication, combining medications, or doubling medication doses will be safe and helpful in decreasing the future risk of fractures.

     
  • Very importantly, even if bone density deteriorates during treatment, it is quite likely that the patient would have lost even more without treatment.

     
  • Recent research has shown that women who lose bone density after the first year of hormone replacement therapy will gain bone density in the next two years, whereas women who gain in the first year will tend to lose density in the next two years of therapy. Therefore, bone density during treatment naturally fluctuates and this may not be relevant to the fracture protection of the medication
     
  • In clinical practice, serial BMD measures have some clinical utility in monitoring response to therapy, but it is important to keep in mind that fracture-protection benefit may be realized before BMD gains are detected
     
  • If there is no change in BMD, it does not mean that therapy is not working, because treatment may have prevented bone loss.

Don’t be concerned if your physician doesn’t order repeated bone density measurements every year. Due to the error of the machine, he or she may not expect your bone density to change in a way that is detectable in such a short time. If you’re taking osteoporosis medications, don’t rely too heavily on repeated bone density testing, because it may not tell you too much about your actual protection against fracture.

In addition to bone densitometry testing, your physician may recommend other types of tests such as blood tests, which may be used to detect the presence of renal (kidney) disease, evaluate the function of the parathyroid gland, evaluate the effects of cortisone therapy, and/or assess the levels of minerals in the body related to bone strength, such as calcium.


BENEFITS OF OSTEOPOROSIS TREATMENT ON FRACTURE RISK MAY BE GREAT, EVEN WHEN IMPROVEMENT IN BONE DENSITY IS SMALL

ORLANDO, FLORIDA—A recent study revealed that reduction in fracture risk from risedronate, a bisphosphonate medication commonly used to treat patients who have osteoporosis, is seen even in patients who have only small improvements in bone mass as measured by bone density, according to research presented this week at the American College of Rheumatology Annual Scientific Meeting in Orlando, Florida.

Researchers reanalyzed data from the HIP and VERT studies of risedronate, which included nearly 9,000 patients from two randomized, double-blind clinical trials. Patients were selected to receive risedronate or placebo based on low bone mineral density (an indicator of bone strength) and/or pre-existing vertebral fracture. All patients also received daily supplements of calcium and vitamin D if baseline levels were low. Researchers examined the relationship between new vertebral fractures and changes in lumbar spine bone mineral density in both the placebo and risedronate groups. The results confirm that increases in bone mineral density results in a reduction in patients’ risk for fracture as compared to those whose bone mineral density decreases. Patients taking risedronate had a decreased risk of fracture compared to those taking placebo. Further, the results show that there was a significant reduction in fracture risk in all patients who had improvements in bone density, and that the reduction in fracture risk was independent of the magnitude of the improvement. Comparisons of bone mineral density increases among different therapies may not translate into meaningful differences in reducing fracture risk.

Fracture is a leading cause of disability in patients with osteoporosis, which affects 10 million people in the U.S., the majority of whom are women.

“Bone density measurements have helped us identify those who are at high risk for fractures,” said Jonathan Adachi, MD, Professor and Director of the Arthritis Centre at St. Joseph’s Hospital-McMaster University in Hamilton, Ontario, Canada, an investigator on the study. “In following patients on therapy, our study suggests that even moderate increases in bone density offer treatment benefit that is not significantly different from larger increases. This suggests that there may be a threshold above which further increases in bone density have little effect on fracture benefit. This also reinforces the need for further research to determine how osteoporosis therapies influence other elements of bone quality that affect the risk of fracture, such as bone turnover and bone micro-architecture.”

The American College of Rheumatology is the professional organization for rheumatologists and health professionals who share a dedication to healing, preventing disability and curing arthritis and related rheumatic and musculoskeletal diseases. For more information on the ACR’s annual meeting, see www.rheumatology.org/annual.