Reader: Kostiv S.Ya.

Osteoporosis is the most common metabolic bone disease and represents an increasingly serious problem, particularly as the population ages. It has been most commonly recognized in elderly white women, although it does occur in both sexes, all races, and all age groups. Osteoporosis is defined by the World Health Organization as a T-score of T-score is the value compared to control subjects who are at their peak bone mineral density, while Z-score reflects a value compared to patients matched for age and sex

Osteoporosis is a condition in which bone mass is low and microarchitectural deterioration of bone tissue occurs, leading to bone fragility and an increased risk of fracture. Homeostasis of bone, a living tissue, is maintained by the osteoclast, which is responsible for bone resorption, and the osteoblast, which is responsible for bone formation. Increased bone resorption or decreased bone formation may result in osteoporosis. Osteoporosis can be caused both by a failure to build bone and reach peak bone mass as a young adult and by bone loss later in life.

Currently, 10 million Americans have osteoporosis. Another 34 million have low bone mass, which leaves them at increased risk for osteoporosis. Each year in the United States, 1.5 million osteoporotic fractures occur. Of these, 700,000 occur in the spine, 300,000 occur in the hip, and 200,000 occur in the wrist. The remainder of fractures occur at other sites in the body.

Patients who have sustained one osteoporotic fracture are at increased risk for developing additional osteoporotic fractures.5 For example, the presence of at least one vertebral fracture results in a 5-fold increased risk of developing another vertebral fracture. Patients with previous hip fracture have a 2- to 10-fold increased risk of sustaining a second hip fracture. In addition, patients with ankle, knee, olecranon, and lumbar spine fractures have a 1.5-, 3.5-, 4.1-, and 4.8-fold increased risk of subsequent hip fracture, respectively

Non-Hispanic white women and Asian women are at increased risk for osteoporosis. An estimated one half of all hip fractures will occur in Asia in the next century. Twenty percent of non-Hispanic white and Asian women aged 50 years or older are estimated to have osteoporosis, and 52% have low bone mass. Ten percent of Hispanic women aged 50 years or older are estimated to have osteoporosis, and 49% have low bone mass. Five percent of non-Hispanic black women older than 50 years are estimated to have osteoporosis, and 35% have low bone mass. Seven percent of non-Hispanic white and Asian men aged 50 years or older have osteoporosis, and 35% have low bone mass. Four percent of non-Hispanic black men aged 50 years or older have osteoporosis, and 19% have low bone mass. Three percent of Hispanic men aged 50 years or older have osteoporosis, and 23% have low bone mass

Physical examination of the patient with osteoporosis may elicit pain, or the patient may be pain free. Thoracic kyphosis may be present secondary to vertebral compression fractures, a dowager hump, and a history of loss of height. Patients may have an associated scoliosis. Patients with acute vertebral fractures may have percussion and/or palpation tenderness over the involved vertebrae

Osteoporosis may be categorized as having both primary and secondary causes. Primary causes may be further divided into modifiable and nonmodifiable risk factors, while secondary causes are attributed to various disease states and medications

Thyroid-stimulating hormone (TSH): Thyroid dysfunction has been associated with osteoporosis and should, therefore, be ruled out. Intact parathyroid hormone (PTH): An intact PTH level is essential in ruling out hyperparathyroidism. An elevated PTH level may be present in benign familial hypocalciuric hypercalcemia (FHH). Calcium: Calcium levels can reflect underlying disease states. Severe hypercalcemia may reflect underlying malignancy or hyperparathyroidism. In addition, hypocalcemia can contribute to osteoporosis. Twenty-four–hour urinary calcium levels: Urinary calcium levels help to rule out benign FHH, in which urinary calcium levels are low. Celiac sprue panels: Celiac sprue has been associated with approximately 5% of osteoporosis cases. Bone alkaline phosphatase: Bone alkaline phosphatase can be mildly elevated in patients with fractures. In addition, patients with hyperparathyroidism, Paget disease, or osteomalacia can have elevations of bone alkaline phosphatase. Serum and urine immunoelectrophoresis: Serum and urine immunoelectrophoresis are used to exclude the presence of multiple myeloma. Urinary N-telopeptide (NTX): NTX, a marker of bone resorption, should be measured. Elevation of this value (>40 nmol bone collagen equivalent per mmol urinary creatine) indicates a high turnover state. NTX levels may also be used to monitor responses to antiosteoporotic treatments. 25-Hydroxyvitamin D and 1,25-hydroxyvitamin D levels: Abnormalities in 25-hydroxyvitamin D and 1,25-hydroxyvitamin D can reflect liver disease and renal disease such as renal osteodystrophy. Inadequate vitamin D levels can predispose persons to osteoporosis.

Radiographic findings can suggest the presence of osteopenia, or bone loss, although they cannot be used to diagnose osteoporosis. Using the second metacarpal or the metaphysis of a long bone, the sum of the cortical width should be at least equal to the medullary width. Osteopenia is suggested by a sum that is less than the medullary width. In addition, 30-40% bone loss must occur before osteopenia is detected on plain radiography. CT scanning may be useful in identifying fractures. CT scanning can be used to identify not only the fracture line but also areas of callus formation and sclerosis, consistent with healing fracture. MRI may be useful in identifying fractures. Using fat suppression sequences, marrow edema consistent with fracture may be noted as areas of hypointensity on T1- weighted images in association with corresponding areas of hyperintensity on T2- weighted images. MRI is a very sensitive modality and is believed by some to be the first diagnostic imaging method of choice in the detection of acute fractures, such as sacral fractures. Bone scanning may be used to identify the presence of multiple osteoporotic fractures. Areas of increased radioactive tracer uptake represent areas of fracture.

Bone biopsy: In situations in which an unexplained recurrent fracture exists in the setting of appropriate antiosteoporotic medical treatment, bone biopsy may be performed. Bone biopsy can help to exclude underlying pathologic conditions such as multiple myeloma, which may be responsible for presumed osteoporotic fracture. Typically, iliac crest biopsy is performed either in the minor procedure suite or in the operating room. One may also perform a vertebral body bone biopsy when performing a therapeutic procedure such as kyphoplasty

Osteoporosis. Lateral radiograph of the patient seen in Image 1 following kyphoplasty performed at 3 additional levels

Osteoporosis. Lateral radiograph demonstrates multiple osteoporotic vertebral compression fractures. Kyphoplasty has been performed at one level

Therapeutic procedures include vertebroplasty and kyphoplasty. Vertebroplasty and kyphoplasty are 2 new minimally invasive spine procedures used for the management of painful osteoporotic vertebral compression fractures

A diet that includes adequate vitamin D and calcium is essential. Recommendations for patients with osteoporosis include daily dosages of IU of vitamin D and mg of calcium. Good sources of calcium include dairy products, sardines, nuts, sunflower seeds, tofu, vegetables such as turnip greens, and fortified food such as orange juice. Good sources of vitamin D include eggs, liver, butter, fatty fish, and fortified food such as milk and orange juice. Patients who ingest inadequate amounts of vitamin D and calcium should receive oral supplementation

Physical activity is important in order to improve balance and maintain and build bone mass, muscle strength, and flexibility. Several different exercises have been shown to be beneficial in patients with osteoporosis

Complications resulting from osteoporotic fracture can include chronic pain from vertebral compression fractures and increased morbidity and mortality secondary to vertebral compression fractures and hip fractures. In addition, overall quality of life can be impaired by the presence of these fractures and their consequences, such as immobility

Patients with osteoporosis can increase bone mineral density and decrease fracture risk with the appropriate antiosteoporotic medication. In addition, patients can decrease their risk of falls by participating in a multifaceted approach that includes rehabilitation (see Activity) and environmental modifications, among others.

Patient education is paramount in the treatment of osteoporosis. Many patients are unaware of the serious consequences of osteoporosis and only become concerned when osteoporosis manifests in the form of fracture. Early prevention and treatment are essential in the appropriate management of osteoporosis. For excellent patient education resources, visit eMedicine's Bone Health Center. Also, see eMedicine's patient education articles Osteoporosis and Understanding Osteoporosis Medications.