Symptoms and Diagnostic Tests
Signs and Symptoms
Anyone who is losing height with age may have osteoporosis; unfortunately, osteoporosis typically has no symptoms at all until a serious fracture occurs, usually from a relatively minor injury (Walker 2010; Azagra 2011). All the while, however, the disease is actually progressing, which is why early prevention is so important (Kawate 2010). Diagnosis and treatment are often substantially delayed, especially in men, because the concept of male osteoporosis is still unfamiliar to many practitioners as well as patients (Kawate 2010).
In women, the “dowager’s hump” that is classically associated with the disease is also a late finding, caused by gradual collapse of the front portion of the bones of the spinal column (Cutler 1993). It is predictive of decreased mobility over the coming years (Katzman 2011). Once fractures are evident, of course, they are associated with symptoms such as pain and immobility. If the hip is fractured, patients are often bedridden for weeks or months, putting them at major risk of pneumonia and blood clots. Hip fracture continues to be a leading cause of death in older adults (Dhanwal 2011).
Dual energy X-ray absorptiometry (or DXA) is considered the gold standard technology for assessing bone mineral density as of the time of this writing (National Osteoporosis Foundation 2013; Clinical Key 2013). It uses X-rays to measure bone density and renders results in grams per square centimeter (g/cm2), with a larger number indicating greater bone mineral density (BMD).
Another technology utilized to determine bone density is quantitative computed tomography (QCT). Like DXA, QCT utilizes X-ray technology to generate a measurement of bone mineral density and expresses results in milligrams per cubic centimeter (mg/cm3) (National Osteoporosis Foundation 2013; Li 2013; Santos 2010). Some evidence suggests that QCT may be more sensitive, relative to DXA, in the detection of osteoporosis; and measures of BMD by QCT may remain somewhat more stable in the context of fluctuating body weight and adiposity (Li 2013; Yu 2012; Smith 2001).
There are some important distinctions between DXA and QCT. First, DXA is associated with modestly less exposure of the patient to ionizing radiation compared to QCT. Specifically, a DXA scan exposes the patient to about .001 – .006 millisieverts (mSv), while a QCT scan of the lumbar spine exposes them to about .09 mSv. (One mSv represents the cumulative background radiation that, on average, a person is exposed to each year in the United States.) However, radiation exposure associated with a QCT scan is still relatively low by comparison to some other common medical scanning techniques. For example, a spinal radiograph exposes the patient to about 0.7 – 2.0 mSv. Next, widely accepted reference ranges are lacking for QCT results, potentially making osteoporosis diagnosis based upon QCT somewhat inconsistent. However, regardless of the chosen methodology for assessing BMD, experienced physicians are usually able to make sound judgments as to bone health and the best path forward for the patient (Adams 2009; Mettler 2008).
The results of bone density testing are given in T-scores. These scores are developed by comparing the person being tested to a young adult of the same gender between 25 and 45 years of age. A T-score of -2.5 or lower indicates high fracture risk, or a 60% chance of fracturing a hip. For every decrease of 1 in T-score, there is a twofold increase in risk of fracture. Individuals with a T-score of -1.1 to -2.5 are diagnosed with osteopenia, or mild bone loss. Results are also given as Z scores, which measures individual results against people of the same age, gender, and race (National Osteoporosis Foundation 2013).
DXA and QCT scans require specialized equipment, keeping them from more widespread use in rural areas. As a result, a variety of predictive scales and scores are being developed that have similar predictive accuracy at substantially less cost. Ultrasonometric scanner (Gueldner 2008), Osteoporosis Prescreening Risk Assessment (OPERA) tool (Salaffi 2005), and Osteoporosis Self-Assessment Tool (OST) (Perez-Castrillon 2007) are a few examples.
The problem, however, with using any of these modalities is that they are useless until substantial bone mineral loss has already occurred (because they rely on measuring that loss). In most people these findings occur only after years of progressive exposure to the chronic, underlying causes of osteoporosis such as oxidant stress, inflammation, insulin resistance, and insufficiency or deficiency of vitamins D and K.