OSTEOPOROSIS: THE SILENT DISEASE
What is osteoporosis?
Osteoporosis is a very common bone disease characterized by an increased fracture risk. To appreciate the difference between “normal” bone and “osteoporotic” bone, think about cheese: normal bone resembles cheddar cheese and osteoporotic bone resembles Swiss cheese. Whereas cheddar cheese is dense and solid, Swiss cheese is full of holes and therefore has a smaller mass for any given volume. As a result, an osteoporotic person’s bones are much more fragile and break much more easily than healthy bones. These fractures are called “fragility fractures,” and most are the result of trauma that ordinarily would not be expected to induce a fracture in an otherwise healthy person.
Fragility fractures can also occur spontaneously without any trauma and then are called “atraumatic fractures.” In these instances, the bones are so weak that they break spontaneously. When this happens, it can cause a fall, rather than the expected occurrence of falling and then breaking a bone. Fragility fractures often occur in the vertebrae, causing the osteoporotic person to suddenly experience severe localized back pain.
Who should be screened for osteoporosis?
Women 65 years of age and older
Men 70 years of age and older
Anyone who has risk factors for osteoporosis such as:
low body weight
sustained a fracture
taking medication that increases the risk of osteoporosis
diagnosed with a disease that increases the risk of osteoporosis
frequent falls or unsteady gait
What causes osteoporosis?
Our skeleton is quite active. Old and weak bone is constantly removed (resorbed) from the skeleton and in its place new, strong bone is formed. In normal adults, these two processes of bone formation and bone resorption go hand-in-hand and are equal, so the skeleton appears to remain unchanged and stable though is really quite dynamic. In children, more bone is formed than resorbed and the bone mass increases. In adults past the age of 35 years, the rate of bone resorption slightly exceeds the rate of bone formation and the bone mass begins to steadily decrease. At the time of menopause, this rate of bone loss is accelerated in about one third of women, leading to osteoporosis.
Estrogen (a hormone produced by the ovaries) is a major factor controlling the rate of bone resorption. It ensures that the rate of bone resorption does not exceed the rate of bone formation. During menopause the ovaries stop producing estrogen, and as a result the rate of bone resorption is increased. When resorption exceeds the rate of bone formation, a person develops osteoporosis.
A number of diseases and medications also can induce osteoporosis.
How is osteoporosis diagnosed?
DEXA scan-a bone densitometry scan that helps classify patients into one of three categories: normal, osteopenia, or osteoporosis.
Fragility Fracture-an atraumatic fracture. Once a patient sustains a fragility fracture, hip fracture risk increases by 77% and risk of any fracture increases by 85%.
Fracture Risk Assessment Algorithm (FRAX)-the probability of sustaining a hip or major fracture over the following ten years.
How common is osteoporosis? Does it affect only women?
Osteoporosis is very common: it affects both sexes. It is estimated that about half the female population over the age of 50 years and one third of the male population over the age of 65 years sustain fractures as a result of osteoporosis.
Osteoporosis is silent until a fracture occurs. Uncomplicated osteoporosis is not associated with any pain, and most patients are not even aware that they have osteoporosis.
What are the risk factors for developing osteoporosis?
Several risk factors have been identified as predisposing to osteoporosis. These can be classified into four distinct groups:
Non-modifiable risk factors, including female gender, Caucasian ethnicity, older age, late menarchy, early menopause, family history of osteoporosis, and especially osteoporotic fracture.
Modifiable risk factors such as low daily calcium and vitamin D intake, cigarette smoking, poor nutrition, sedentary lifestyle, and excessive caffeine and sodium intake (including soft drinks).
Disease states such as vitamin D deficiency, female athlete syndrome, hyperparathyroidism, status post bariatric surgery, hypogonadism, renal impairment, thyroid dysfunction, depression, anorexia nervosa, and malabsorption.
Medications such as corticosteroids (prednisone and other similar agents), cancer medication, and anti-epileptics.
Does everybody with osteoporosis sustain a fracture?
No, not every person with osteoporosis sustains a fracture, and many people who sustain fractures do not have osteoporosis. But those who do have osteoporosis are much more likely to sustain fractures, and if they are not treated for osteoporosis are likely to sustain even more fractures.
Unfortunately, many patients with osteoporosis who sustain fractures are neither diagnosed nor treated for osteoporosis. The National Committee for Quality Assurance reported in 2013 that only one quarter of the patients who sustained fragility fractures are diagnosed and treated for osteoporosis. In other words, 75% of patients with osteoporosis and fractures are not treated for osteoporosis.
Fractures in patients with osteoporosis are often life-changing events: mortality within one year of the fracture is increased, and many patients have to curtail their physical activities and are no longer able to resume many of their social activities. Ideally, the diagnosis of osteoporosis should be established prior to the patient sustaining a fracture. Prevention is better than cure!
What treatments are available for osteoporosis?
As osteoporosis is due to the rate of bone resorption exceeding the rate of bone formation, there are essentially two types of medications that can be used to treat osteoporosis:
Anti-resorptive medications, which reduce the risk of bone resorption, such as bisphosphonates: alendronate (Fosamax), risedronate (Actonel), ibandronate (Boniva), zoledronic acid (Reclast) and denosumab (Prolia).
Anabolic medications which increase the rate of bone formation, such as teriparatide (Forteo) and abaloparatide (Tymlos).
Raloxifene (Evista) is a medication similar to estrogen, but without some of its adverse effects. (Estrogen is no longer approved by the FDA for the treatment of osteoporosis, although it is still approved for the prevention of osteoporosis, provided it is given in the smallest possible dose and for the shortest period of time.) All of these medications have been shown to significantly increase the bone mineral density and reduce the risk of fractures.
It is very important to emphasize that the medication treatment of osteoporosis is only one component of the management strategy. For best results, patients should have an adequate daily calcium and vitamin D intake and a good nutritious diet. In addition, patients must refrain from cigarette smoking and reduce caffeine and sodium intake (which both increase the amount of calcium lost in the urine). A physically active lifestyle and regular exercise are also of paramount importance to maximize the effect of the medications prescribed.
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