How do you test for Osteoporosis?
Osteoporosis is a condition of low bone density that can progress silently over a long period of time. If diagnosed early, the fractures associated with the disease can often be prevented. Unfortunately, osteoporosis frequently remains undiagnosed until a fracture occurs.
An examination to diagnose osteoporosis can involve several steps that predict your chances of future fracture, diagnose osteoporosis, or both. It might include:
an initial physical exam
various x rays that detect skeletal problems
laboratory tests that reveal important information about the metabolic process of bone breakdown and formation
a bone density test to detect low bone density.
Before performing any tests, your doctor will record information about your medical history and lifestyle and will ask questions related to:
risk factors, including information about any fractures you have had
your family history of disease, including osteoporosis
general intake of calcium and vitamin D
for women, menstrual history.
In addition, the doctor will note medical problems and medications you may be taking that can contribute to bone loss (including glucocorticoids, such as cortisone). He or she will also check your height for changes and your posture to note any curvature of the spine from vertebral fractures, which is known as kyphosis.
For most women, your doctor will be able to diagnose your condition without additional tests. However, where appropriate, your doctor may use special equipment to conduct a bone mineral density test (BMD).
DEXA (dual-energy x-ray absorptiometry)
The most common test for diagnosing osteoporosis is called dual energy x-ray absorptiometry (DEXA). In this procedure, x-rays are used to take a picture of the insides of your bone and to determine if they have become porous due to osteoporosis. The DXA test measures your bone mineral density and compares it to an establish benchmark / norm level. The most common comparison is to the peek or ideal bone mineral density in a health 30 year old adult.
The result of this comparison is something called a t-score. This is just a statistical measure that tells your doctor how your bone density compares to the normal population.
T-Score Outcomes (World Health Organization)
T-score between -1.0 to +1.0. A normal adult is considered to have a t-score of 0.0.
Low Bone Mass (Osteopenia)
T-score between -1.0 and -2.5
T-score of -2.5 or lower
Severe (established) osteoporosis
T-score of -2.5 or lower and there have been one or more osteoporotic fractures
Other tests used to measure bone density mass include conventional x-rays, and quantitative computed tomography (QCT), quantitative ultrasound, and measurement of bone thickness in the peripheral skeleton (i.e. away from the spine, like your wrist, heel, or finger).
Most doctors recommend that individuals aged 65 or older should have a bone density test. Individuals aged 60 – 64 with low weight (< 154 lbs.) and not on hormone replacement therapy (estrogen supplementation) are also recommended to get a bone density test.
For some people, a bone scan may be ordered. A bone scan is different from the BMD test just described, although the term “bone scan” often is used incorrectly to describe a bone density test. A bone scan can tell the doctor whether there are changes that may indicate cancer, bone lesions, inflammation, or new fractures. In a bone scan, the person being tested is injected with a dye that allows a scanner to identify differences in the conditions of various areas of bone tissue.
A number of laboratory tests may be performed on blood and urine samples. The results of these tests can help your doctor identify conditions that may be contributing to your bone loss.
The most common blood tests evaluate:
blood calcium levels
blood vitamin D levels
parathyroid hormone levels
estradiol levels to measure estrogen (in women)
follicle stimulating hormone (FSH) test to establish menopause status
testosterone levels (in men)
osteocalcin levels to measure bone formation.
The most common urine tests are:
24-hour urine collection to measure calcium metabolism
tests to measure the rate at which a person is breaking down or resorbing bone.