Osteoporosis
In a healthy adult the skeleton is maintained through a process of complementary bone resorption and deposition (Das & Crockett, 2013). The two cell types responsible for this process are the multinucleated osteoclasts derived from the blood and resident osteoblasts. In the course of normal living the skeleton will develop localized, stress-induced microfractures, which trigger resident osteocytes to signal for help from the osteoclasts. The osteoclasts arrive and begin to degrade old bone, while osteoblasts engage in the regeneration process.
As people age the balance between mineralized bone resorption and deposition can become skewed to favor resorption over deposition (Das & Crockett, 2013). This is especially true for post-menopausal women because estrogen has been shown to be essential for maintaining a healthy balance between osteoclast and osteoblast activity. This case study examines a 65-year-old woman who has been diagnosed with osteoporosis using a bone density scan. The meaning and implications of the diagnosis will be reviewed, along with recommended treatment approaches.
Diagnosing Osteoporosis
Current recommendations are for all women over the age of 65-years to be screened for osteoporosis (U.S. Preventive Services Task Force, 2011; ACOG, 2013). A bone mineral density scan using dual energy X-ray absorptiometry (DEXA) is the gold standard for screening. If the results are equal to or more than 2.5 standard deviations away from the reference mean then the person is diagnosed with osteoporosis. The reference mean and standard deviation is based on young adult White women, because White women generally have a higher risk of fractures due to bone loss than non-White women (U.S. Preventive Services Task Force, 2011). The recommended DEXA screening interval is every two years, but if the patient is being treated then more frequent screens could be done...
The recommended locations for a bone density scan for osteoporosis is the femoral neck, lumbar spine, and/or hip (ISCD, 2013), although if these locations cannot be easily scanned then the non-dominant forearm can be used as a point of reference (Mounach et al., 2009). The reason for using two or more locations is due to frequent reports of discordant readings. Minor discordant readings result when one location gives a normal or osteopenia measurement at one location and an osteopenia or osteoporosis measurement at the other location. A major discordance occurs when one location is normal and the other osteoporotic. A recent study by Mounach and colleagues (2009) revealed that minor discordances are common (46%), but major discordant readings are relatively rare (4%). The authors of this study found that age, obesity, and menopause increased the risk of discordance in a study population consisting of mostly women between the ages of 20 and 92 years.
Implications of an Osteoporosis Diagnosis
The 65-year-old patient in this case study could have been diagnosed with osteoporosis during the course of a routine physical, or more commonly after having suffered a low-trauma fracture (Baim & Leslie, 2012). Regardless of what led to the decision to screen for osteoporosis, the use of the T-score for discriminating between high-risk and low-risk patients for low-trauma fractures has its limitations. For example, researchers have discovered that the majority of low-trauma fractures occur in individuals who have a T-score in the normal range. The T-score is therefore based on evidence showing that bone density more than 2.5 standard deviation from the reference mean defines a…
