Osteoporosis is a metabolic bone disorder in which bone tissue breaks down, making bone become increasingly fragile, leading to an increasing risk of fracture. Osteoporosis (and osteopenia, which refers to low bone density in general), can affect people of all ages.
Bone loss in adolescence and early adulthood can be a result of a failure to attain peak bone mineral density, and accelerated bone loss may be particularly noted around menopause and in later years. Many factors, including diet and the lack of proper exercise, contribute to bone loss during these periods. It can also occur as a result of numerous underlying conditions, many of which are often not readily apparent during the course of a doctor visit.
Therefore, laboratory testing, including serum and urine studies, is helpful in discerning its secondary causes.
A common misconception is that osteoporosis is a disease only found in the elderly. However, it is quite common for young persons, even in their teens and twenties, to be diagnosed with osteopenia or osteoporosis.
The diagnosis may become apparent following the development of fractures, though one can have osteopenia or osteoporosis without having had a fracture. Risk factors for osteopenia and osteoporosis include personal history of fracture, eating disorders, or excessive use of medications such as oral corticosteroids (i.e. hydrocortisone). Young female athletes are particularly at risk. For example, the female athlete triad is a condition in which there is disordered eating, amenorrhea, and osteopenia. This triad represents a significant problem in young female athletes who restrict their caloric intake and exercise excessively, thereby developing amenorrhea. This condition interferes with the attainment of peak bone mass occurring during the crucial bone building years, up to the age of 30. Bone density lost during this period is not fully recovered with the eventual return of normal menstrual function. This is why prevention in young athletic woman is the best treatment.
Identification of osteopenia and osteoporosis in young persons is in some ways even more important than in older individuals, because these individuals have less bone density to begin with and they have a higher likelihood of developing more severe osteoporosis over the course of a lifetime, including complications such as multiple fractures and spinal deformities. Therefore, it should be stressed that individuals with fractures or risk factors for osteopenia and osteoporosis undergo a thorough evaluation with appropriate treatment and close follow-up.
Another common and dangerous misperception is the association of osteoporosis with women, a view that neglects 20% of all cases of the disease. As a result, men with fractures or other significant risk factors for osteoporosis, such as prolonged treatment with oral corticosteroids or medications interfering with male hormones, often underestimate their risk.
Diagnosis of osteoporosis is made with BMD (bone mineral density) testing. BMD is measured by dual energy X-ray absorptiometry (DXA – commonly pronounced "dexa"), which measures both mineral content and bone size.
Another DXA imaging technique, instant vertebral assessment (IVA), also known as morphometric X-ray absorptiometry (MXA), determines vertebral body shape. It can help to detect early vertebral fractures and has been shown to detect these fractures in almost 20% of asymptomatic women.
Interpretations of BMD results should be performed with care, as there are potential confusing factors. For example, the presence of osteoarthritis in the spine can make BMD appear better than it actually is by elevating the reading. Lateral spine DXA selectively measures the trabecular spine without the interference of the spinous processes and appears to be more sensitive to age-related bone loss than posterior-anterior DXA. Hip BMD is more accurate in women over 60 years of age because of the prevalence of osteoarthritis in the spine in the elderly.
Precision errors should be considered when evaluating serial BMD examinations. Such errors can be compounded when different DXA machines are utilized and the results are then compared.
Certain individuals with osteoporotic fractures and suspected osteopenia and osteoporosis should undergo thorough laboratory investigation consisting of blood and urine tests to help rule out secondary causes of osteoporosis. Laboratory studies include a complete metabolic panel, complete blood count, 24-hour urine study, sedimentation rate, and tests of the parathyroid hormone, thyroid hormone, urinary N-telopeptide and others.
These laboratories can assess for bone turnover and help to rule out the presence of underlying conditions such as hyperparathyroidism, hyperthyroidism, and rarer conditions such as diseases of the bone marrow, like multiple myeloma. The incidence of underlying conditions in women with bone loss is approximately 9%, while the incidence increases significantly to 66% in men with bone loss.
Since the presence of vertebral deformity significantly increases the risk for additional vertebral fractures and hip fractures, radiographs may be very important by helping to detect the presence of silent osteoporotic fractures, particularly in the spine. Patients with vertebral deformities have a 5.4 and 2.8 relative risk of developing vertebral and hip fractures, respectively. In addition, though not specific or used as a diagnostic tool, the appearance of bone on radiographs can give a gross estimation of bone density.
Once underlying causes of osteoporosis and osteopenia are identified, appropriate treatment is necessary. A comprehensive treatment approach involves both medical and non-medical management:
Medical treatment involves administration of calcium and vitamin D and additional anti-osteoporotic medication as well as correction of underlying conditions. For example, hyperthyroidism may require medical and/or surgical correction. Specific deficiencies of calcium and vitamin D require adequate supplementation.
First line treatment for osteoporosis and osteopenia consists of calcium and vitamin D supplementation as well as bisphosphonate medication. The bisphosphonates, which are anti-resorptive medications or medications which slow the breakdown of bone, are a class of medications which include oral alendronate (Fosamax) and risedronate (Actonel), as well as the intravenous aredia (Pamidronate), ibandronate (Boniva). Unlike the bisphosphonates, there are anabolic agents that stimulate bone formation. Parathyroid hormone (Forteo) is one of these stimulating agents.
Weight bearing exercise is necessary in order to stimulate adequate bone formation, and exercises such as running and jumping have been shown to be particularly effective in enhancing bone formation. Fall prevention includes measures such as modification of one's environment, minimizing medications known to increase falls risk, wearing appropriate footwear, and participating in exercise programs which enhance strength, balance, and flexibility.
In addition, hip fracture prevention may be achieved with the use of hip protectors, which are external orthoses that help to absorb the forces of a fall. Good nutritional intake is important – particularly in women – to ensure preservation of menstrual cycles. Inadequate caloric intake can result in cessation of menses leading to bone loss. Menstrual cycle irregularities should be corrected as necessary by addressing aberrant eating patterns to restore the proper energy balance and return of normal menses. Treatment with oral contraceptive pills or other appropriate treatments may be necessary.
Osteopenia and osteoporosis are conditions that are extremely amenable to treatment. However, early diagnosis and treatment is essential to prevent complications of osteoporosis such as fractures and deformity. Unfortunately, treatment options for osteopenia and osteoporosis are often overlooked, but appropriately trained physicians can provide comprehensive treatment programs incorporating both medical and non-medical management for these conditions.
Reviewed and Updated by Dr. Elizabeth M. Manejias