Osteoporosis is a metabolic bone disease affecting more than 10 million Americans. About 34 million Americans have low bone mass, which puts them at risk for developing the disease. Each year, an estimated 1.5 million fractures occur because of osteoporosis. In particular, it affects women who are older than age 50, postmenopausal, or small boned, or who come from a northern European, especially Scandinavian, background. The total bone mass for someone affected by osteoporosis is less than expected for the individual’s age and sex. The proportion of bone mineral to bone matrix is normal, however, and there usually is no detectable abnormality of bone composition. Bones become brittle, porous, and vulnerable to fracture because of the decreased calcium and phosphate in bones.
FIGURE. (A) Normal spongy bone, as in the body of a vertebra. (B) Spongy bone thinned by osteoporosis. (From Scanlon, VC, and Sanders, T: Essentials of Anatomy and Physiology, ed 4. FA Davis, Philadelphia, 2003, p 107, with permission.)
Recent research indicates that heredity plays a role in osteoporosis. Genes influence bone density. In some instances, osteoporosis is a manifestation of another disease, prolonged steroid therapy, alcoholism, lactose intolerance, or hyperthyroidism. Possible contributing factors to osteoporosis include low lifetime intake of calcium, a diet high in protein and fat, a sedentary lifestyle, poor or declining adrenal function, faulty protein metabolism due to estrogen deficiency, vitamin D deficiency, cigarette smoking, and amenorrhea. In men, low testosterone levels, especially in those who smoke cigarettes, increase the risk of osteoporosis.
Signs and Symptoms
Symptoms of osteoporosis may go undiscovered until there is a presenting fracture, mostly because the disorder has long been considered a “traumatic” condition. Symptoms include bone pain, especially in the lower back and in the weight-bearing bones. The vertebrae, hips, and wrists are particularly susceptible to osteoporotic fractures. Over time, clients may notice a loss of height and/or kyphosis.
Dual-energy x-ray absorptiometry (DEXA) is a diagnostic scan that primary care providers use in the clinical setting to measure bone mineral density at sites especially susceptible to fracture. This test allows for a diagnosis of osteoporosis before any fracture occurs. Blood tests are run to measure levels of phosphorus, alkaline phosphatase, total protein, albumin, and creatine. Excretion of calcium, phosphate, creatinine, and hydroxyproline also may be monitored through urinalysis. X-rays are helpful but may be difficult to interpret in cases of osteoporosis because the density of skeletal parts may appear to be similar to that of soft tissue. A bone scintiscan, bone biopsy, or CT scan may be ordered if more specific diagnostic data are necessary.
The goal is to prevent fracture and control pain. The treatment depends on the cause. Increased dietary calcium, phosphate supplements, and multivitamins may be prescribed. Bisphosphonates that slow or prevent the breakdown and resorption of bone are now the first treatment of choice for both men and women with osteoporosis. These drugs include alendronate (Fosamax), risedronate (Actonel), and ibandronate (Boniva). For postmenopausal women, zoledronic acid (Zometa, Zomera, Aclasta, and Reclast) given in a single yearly intravenous (IV) dose has been able to lessen spinal and hip fractures. Lifetime daily injections of teriparatide (brand name Forteo), which is similar to parathyroid hormone, seems to direct osteoblasts to mature and prevents them from dying. The thyroid hormone calcitonin may be prescribed subcutaneously or via nasal spray to decrease bone resorption. Exercise helps minimize osteoporosis by slowing loss of mineral calcium, but if the bones have become brittle, exercise may need to be modified to prevent injury. Analgesics and muscle relaxants may be needed if pain or muscle spasms are a problem. Frequent rest periods are advised if bone pain is severe.
Supplements of natural sources of calcium should be the focus of complementary therapy. Natural sources of calcium include milk, yogurt, cheese, ice cream, sardines, clams, oysters, and salmon. Balancing the body’s hormone production, regulating diet, and getting proper exercise can be helpful. It is recommended that clients stop smoking. A diet high in protein, sugar, soft drinks, caffeine, alcohol, and fried foods has an acidifying affect on the body and causes calcium to be drawn from the bones. Vitamins B, C, and D, as well as magnesium, zinc, and phosphorous, are also important for bone health.
Teach clients about a balanced diet that is not overly high in protein. Proper body mechanics are important to reduce possible fractures. Weight-bearing exercise, such as running and strength training, is essential for building bone but may need to be modified for some clients.
The prognosis for osteoporosis is mostly dictated by the cause. The major problem is the risk of fractures. That risk grows exponentially as an individual’s age increases and bone mass weakens. Drugs are now available that can restore lost bone and reduce the risk of fracture. Osteoporosis can cause permanent disability.
Prevention of osteoporosis includes a calcium-rich diet. Premenopausal women need at least 1000 mg of calcium and 800 mg of vitamin D daily. Women over age 65 should increase the dosage of calcium to at least 1500 mg daily. A person at risk may need to take more calcium and vitamins and to exercise 20 minutes daily. The U.S. Preventive Services Task Force recommends DEXA screening for women age 65 and over.
Risk Factors for Osteoporosis
- Over age 50
- Family history of osteoporosis
- Thin, small-framed body
- Caucasian or Asian
- History of broken bones after age 50
- Low estrogen levels
- Alcohol (three or more drinks per day)
- Inactive lifestyle
- Certain medications (e.g., corticosteroids)
- Eating disorders
- Celiac disease