The genetic and immune factors that cause osteoporosis are very complex. Strong evidence demonstrates that genetics is a significant factor, with a heritability of 50% to 90% (Chang et al., 2010). Many genetic changes have been identified as possible causative factors, but there is no agreement about which ones are most important or constant in all patients. For example, changes in the vitamin D receptor (VDR) gene and calcitonin receptor (CTR) gene have been found in some patients with the disease. Receptors are essential for the uptake and use of these substances by the cells.

The bone morphogenetic protein-2 (BMP-2) gene has a key role in bone formation and maintenance. Some osteoporotic patients who have had fractures have changes in their BMP-2 gene. Alterations in growth hormone-1 (GH-1) have been discovered in petite Asian-American women, those who are predisposed to developing osteoporosis.

Hormones, tumor necrosis factor (TNF), interleukins, and other substances in the body help control osteoclasts in a very complex pathway. The recent identification of the importance of the cytokine receptor activator of nuclear factor kappa-B ligand (RANKL), its receptor RANK, and its decoy receptor osteoprotegerin (OPG) has helped researchers understand more about the activity of osteoclasts in metabolic bone disease. Disruptions in the RANKL, RANK, and OPG system can lead to increased osteoclast activity in which bone is rapidly broken down (McCance et al., 2010).

Primary osteoporosis most often occurs in women after menopause as a result of decreased estrogen levels. Women lose about 2% of their bone mass every year in the first 5 years after natural or surgical (ovary removal) menopause. For women of any age who do not take estrogen replacement, the risk for osteoporosis increases.

Men also develop osteoporosis after the age of 50 because their testosterone levels decrease. Testosterone is the major sex hormone that builds bone tissue. Men are often underdiagnosed, even when they become older adults. A recent study of almost 1200 men in a VA rehabilitation center showed that screening for osteoporosis had not been conducted. As a result of bone mineral density screening, the researchers found 33 study patients who had osteoporosis and were at high risk for fractures, especially of the hip. Those who were diagnosed with the disease were the oldest patients who had a lower body mass index and weight (Swislocki et al., 2010).

Body build and weight seems to influence who gets the disease. Osteoporosis occurs most often in older, lean-built Euro-American and Asian women, particularly those who do not exercise regularly. However, African Americans are at risk for decreased vitamin D, which is needed for adequate calcium absorption in the small intestines. Obese women can store estrogen in their tissues for use as necessary to maintain a normal level of serum calcium. Weight-bearing exercise reduces bone resorption (loss) and stimulates bone formation. Prolonged immobility produces rapid bone loss.

The relationship of osteoporosis to nutrition is well established. For example, excessive caffeine in the diet can cause calcium loss in the urine. A diet lacking enough calcium and vitamin D stimulates the parathyroid gland to produce parathyroid hormone (PTH). PTH triggers the release of calcium from the bony matrix. Activated vitamin D is needed for calcium uptake in the body. Malabsorption of nutrients in the GI tract also contributes to low serum calcium levels. Institutionalized or homebound patients who are not exposed to sunlight may be at a higher risk because they do not receive adequate vitamin D for the metabolism of calcium.

Calcium loss occurs at a more rapid rate when phosphorus intake is high. (Chapter 13 describes the usual relationship between calcium and phosphorus in the body.) People who drink large amounts of carbonated beverages each day (over 40 ounces) are at high risk for calcium loss and subsequent osteoporosis, regardless of age or gender.

Protein deficiency may also reduce bone density. Because 50% of serum calcium is protein bound, protein is needed to use calcium. However, excessive protein intake may increase calcium loss in the urine. For instance, people who are on high-protein, low-carbohydrate diets, like the Atkins diet, may consume too much protein to replace other food not allowed. Dietary protein intake in healthy adults is recommended at 0.8 grams per kilogram of body weight. Protein is needed for bone healing when a fracture occurs.

Excessive alcohol and tobacco use are other risk factors for osteoporosis. Although the exact mechanisms are not known, these substances promote acidosis, which in turn increases bone loss. Alcohol also has a direct toxic effect on bone tissue, resulting in decreased bone formation and increased bone resorption. For those people who have excessive alcohol intake, alcohol calories decrease hunger and the need to take in adequate amounts of nutrients.

Osteoporosis also occurs in young adults who participate in excessive exercise or weight-loss dieting or in those who have eating disorders, such as anorexia nervosa or bulimia nervosa. Young females with these risk factors have a low body weight and absent menstruation, which contribute to the development of osteoporosis. Dancers, gymnasts, and other athletes may overtrain without sufficient caloric intake, which also results in severe weight loss. Young girls and women may have an obsession with being slim. Particular attention must be paid to bone health for these groups.

Incidence/Prevalence

Osteoporosis is a potential health problem for more than 44 million Americans. About 10 million people in the United States have the disease, and about 34 million people 50 years of age and older have osteopenia and are at risk for development of osteoporosis. Women remain the largest group affected by osteoporosis, although men, especially those older than 75 years, also have the disease. After the age of 50, men are at increased risk for osteoporosis and osteoporotic-related fractures (Voda, 2009b).

People of all ethnic and racial backgrounds are at some degree of risk, but white, thin women are likely to get primary osteoporosis at an earlier age (National Osteoporosis Foundation, 2010).

Cultural Awareness

Although there is some advantage of increased bone density in dark-skinned women, lifestyle and health beliefs about prevention may put all women at an equal risk for osteoporosis. Dietary preferences or the ability to afford high-nutrient food may influence the woman’s rate of bone loss. For example, many blacks have lactose intolerance and cannot drink milk or eat other dairy-based foods. Milk and cheese are good sources of protein, a nutrient needed to bind calcium for use by the body.

Osteoporosis results in more than 1.5 million fractures each year. A woman who experiences a hip fracture has a four times greater risk for a second fracture. Fractures as a result of osteoporosis and falling can decrease a patient’s mobility and quality of life. The mortality rate for older patients with hip fractures is very high, especially within the first 6 months, and the debilitating effects can be devastating.

Nursing home residents fall 11 times more often than their community-dwelling counterparts (Parikh et al., 2009). Yet, skilled nursing facilities (SNFs) do not routinely screen residents for osteoporosis. A national study by Gloth and Simonson (2008) reported the results of osteoporosis screening for more than 34,000 SNF residents in 26 states. Over 42% of residents were categorized as having a high risk for osteoporosis and associated fractures (see the Evidence-Based Practice box on p. 1122).

Evidence-Based Practice

Is Osteoporosis Underdiagnosed in Residents Admitted to Skilled Nursing Facilities?

Gloth, F.M., 3rd, & Simonson, W. (2008). Osteoporosis is underdiagnosed in skilled nursing facilities: A large-scale heel BMD screening study. Journal of the American Medical Directors Association, 9(3), 190-193.

The purpose of this nationwide study in the United States was to investigate the belief that osteoporosis is underdiagnosed in the skilled nursing facility (SNF) setting. Local consultant pharmacists screened 34,486 SNF residents in 26 states using the peripheral dual-energy x-ray absorptiometry (DXA) scan to determine bone mineral density (BMD) of the heel. Residents ranged in age from younger than 59 years to older than 80 years. Of the total screened residents, 22.4% were categorized as low risk, 35.1% as moderate risk, and 42.5% as high risk for osteoporosis and related fractures. The researchers concluded that osteoporosis is grossly underdiagnosed and BMD screening should be a part of the resident’s admission assessment.

Patient-Centered Collaborative Care

Assessment

A complete health history with assessment of risk factors is important in the prevention, early detection, and treatment of osteoporosis. Patients who have risk factors for osteoporosis are at increased risk for fractures when falls occur. Include a fall risk assessment in the health history, especially for older adults. Assess for fall risk factors, including:

• Visual or hearing deficits

• Current drugs

The Joint Commission’s National Patient Safety Goals (NPSG) specify the need to reduce risk for harm to patients resulting from falls. People with osteoporosis are at an increased risk for fracture if a fall occurs. The World Health Organization (WHO) Fracture Risk Algorithm (FRAX) is often used to determine the patient’s risk for fractures associated with bone loss. Chapter 3 discusses falls in older adults in more detail.

Physical Assessment/Clinical Manifestations

When performing a musculoskeletal assessment, inspect and palpate the vertebral column. The classic “dowager’s hump,” or kyphosis of the dorsal spine, is often present (Fig. 53-1). The patient may state that he or she has gotten shorter, perhaps as much as 2 to 3 inches (5 to 7.5 cm) within the previous 20 years. Take or delegate height and weight measurements, and compare with previous measurements if they are available.

FIG. 53-1 A normal spine at age 40 years and osteoporotic changes at ages 60 and 70 years. These changes can cause a loss of as much as 6 inches in height and can result in the so-called dowager’s hump (far right) in the upper thoracic vertebrae.

The patient may have back pain, which often occurs after lifting, bending, or stooping. The pain may be sharp and acute in onset. Pain is worse with activity and is relieved by rest. Palpation of the vertebrae, particularly the lower thoracic and lumbar vertebrae, can increase the patient’s discomfort. Therefore palpation should be gentle.

Back pain accompanied by tenderness and voluntary restriction of spinal movement suggests one or more compression vertebral fractures, the most common type of osteoporotic fracture. Movement restriction and spinal deformity may result in constipation, abdominal distention, reflux esophagitis, and respiratory compromise in severe cases. The most likely area for spinal fracture is between T8 and L3. This problem is discussed in more detail in Chapter 54.

Fractures are also common in the distal end of the radius (wrist) and the upper third of the femur (hip). Ask the patient to locate all areas that are painful, and observe for signs and symptoms of fractures, such as swelling and malalignment.

Psychosocial Assessment

Women associate osteoporosis with menopause, getting older, and becoming less independent. The disease can result in suffering, deformity, and disability that can affect the patient’s well-being and life satisfaction. The quality of life may be further impacted by pain, insomnia, depression, and fallophobia (fear of falling).

Assess the patient’s concept of body image, especially if he or she is severely kyphotic. For example, the patient may have difficulty finding clothes that fit properly. Social interactions may be avoided because of a change in appearance or the physical limitations of being unable to sit in chairs in restaurants, movie theaters, and other places. Changes in sexuality may occur as a result of poor self-esteem or the discomfort caused by positioning during intercourse.

Because osteoporosis poses a risk for fractures, teach the patient to be extremely cautious about activities. As a result, the threat of fracture can create anxiety and fear and result in further limitation of social or physical activities. Assess for these feelings to assist in treatment decisions and health teaching. For example, the patient may not exercise as prescribed for fear that a fracture will occur.

Laboratory Assessment

There are no definitive laboratory tests that confirm a diagnosis of primary osteoporosis, although a number of biochemical markers can provide information about bone resorption and formation activity. These biochemical markers are sensitive to bone changes and can be used to monitor effectiveness of treatment for osteoporosis. Bone-specific alkaline phosphatase (BSAP) is found in the cell membrane of the osteoblast and indicates bone formation status. Osteocalcin is a protein substance in bone and increases during bone resorption activity. Pyridinium (PYD) cross-links are released into circulation during bone resorption. N-teleopeptide (NTX) and C-teleopeptide (CTX) are proteins released when bone is broken down. Some laboratories require a 24-hour urine collection for testing, whereas others use a double-voided specimen. Some markers, like NTX and CTX, can also be measured in the blood using immunoassay techniques. Increased levels of any of these markers indicate a risk for osteoporosis. Increased levels are found in patients with osteoporosis, Paget’s disease, and bone tumors (Pagana & Pagana, 2010).

A battery of tests can be performed to rule out secondary osteoporosis or other metabolic bone diseases, such as osteomalacia and Paget’s disease. These include measurements of serum calcium, vitamin D, and phosphorus. Urinary calcium levels may also be assessed. Serum protein measurements and thyroid function tests are done to check for hyperthyroidism.

Imaging Assessment

Conventional x-rays of the spine and long bones show decreased bone density but only after a 25% to 40% bone loss has occurred. Fractures can also be seen on x-ray.

The most commonly used screening and diagnostic tool for measuring bone mineral density (BMD) is dual x-ray absorptiometry (DXA). The spine and hip are most often assessed when central DXA (cDXA) scan is performed. Many physicians recommend that women in their 40s have a baseline screening DXA scan so that later bone changes can be detected and compared. DXA is a painless scan that emits less radiation than a chest x-ray. It is the best tool currently available for a definite diagnosis of osteoporosis. The patient stays dressed but is asked to remove any metallic objects such as belt buckles, coins, keys, or jewelry that might interfere with the test. The results are displayed on a computer graph, and a T-score is calculated. No special follow-up care for the test is required. However, the patient needs to discuss the results with the physician for any decisions about possible preventive or management interventions.

A peripheral DXA (pDXA) scan assesses BMD of the heel, forearm, or finger. It is often used for large-scale screening purposes. For example, Gloth and Simonson (2008) reported a large-scale heel BMD study for screening over 34,000 skilled nursing facility residents. The pDXA is also commonly used for screening at community health fairs and women’s health centers.

Quantitative computed tomography (QCT) can also measure bone density, using either a central or peripheral technique. This procedure analyzes trabecular and cortical bone separately and is especially sensitive to changes in the vertebral column. The test is more expensive than the DXA scan and exposes the patient to more radiation; however, it is a safe screening test (National Osteoporosis Foundation, 2010).

Peripheral quantitative ultrasound (pQUS) is an effective and low-cost peripheral screening tool that can detect osteoporosis and predict risk for hip fracture. The heel, tibia, and patella are most commonly tested. The procedure requires no special preparation, is quick, and has no radiation exposure or specific follow-up care (Pagana & Pagana, 2010). The National Osteoporosis Foundation recommends that men older than 70 years have the pQUS as a screening tool for the disease.

Analysis

The most common problem for patients with osteoporosis or osteopenia is potential for fractures related to weak, porous bone tissue.

Planning and Implementation

Planning: Expected Outcomes

The expected outcome is that the patient avoids fractures by preventing falls, managing risk factors, and adhering to preventive or treatment measures for bone loss.

Interventions

Because the patient is predisposed to fractures, nutritional therapy, exercise, lifestyle changes, and drug therapy are used to slow bone resorption and form new bone tissue. Patient education can help prevent osteoporosis or slow the progress. These measures help reduce the chance of fractures and their complications. The role of drug therapy has increased over the past decade and helps prevent fractures related to osteoporosis. Drug therapy should begin when the BMD T-score for the hip is below −2.0 with no other risk factors or when the T-score is below −1.5 with one or more risk factors or previous fracture.

Nutrition Therapy

The nutritional considerations for the treatment of a patient with a diagnosis of osteoporosis are the same as those for preventing the disease. Teach patients about the adequate amounts of protein, magnesium, vitamin K, and trace minerals that are needed for bone formation. Calcium and vitamin D intake should be increased. Teach patients to avoid excessive alcohol and caffeine consumption. For the patient who has sustained a fracture, adequate intake of protein, vitamin C, and iron is important to promote bone healing. People who are lactose intolerant can choose a variety of soy and rice products that are fortified with calcium and vitamin D. In addition, calcium and vitamin D are added to many fruit juices, bread, and cereal products.

A variety of nutrients are needed to maintain bone health. The promotion of a single nutrient will not prevent or treat osteoporosis. Help the patient develop a nutritional plan that is most beneficial in maintaining bone health; the plan should emphasize fruits and vegetables, low-fat dairy and protein sources, increased fiber, and moderation in alcohol and caffeine (National Osteoporosis Foundation, 2010).

Lifestyle Changes

Exercise is important in the prevention and management of osteoporosis. It also plays a vital role in pain management, cardiovascular function, and an improved sense of well-being.

In collaboration with the health care provider, the physical therapist may prescribe exercises for strengthening the abdominal and back muscles for those at risk for vertebral fractures. These exercises improve posture and support for the spine. Abdominal muscle tightening, deep breathing, and pectoral stretching are stressed to increase lung capacity. Exercises for the extremity muscles include muscle-tightening, resistive, and range-of-motion (ROM) exercises. Encourage active ROM exercises, which improve joint mobility and increase muscle tone, as well as prescribed exercise activities. Swimming provides overall muscle exercise.

In addition to exercises for muscle strengthening, a general weight-bearing exercise program should be implemented. Teach patients that walking for 30 minutes three to five times a week is the single most effective exercise for osteoporosis prevention. Teach the patient that certain high-impact recreational activities, such as running, bowling, and horseback riding, may cause vertebral compression fractures and should be avoided.

In addition to nutrition and exercise, other lifestyle changes may be needed. Teach the patient to avoid tobacco in any form, especially cigarette smoking. The patient must be careful to prevent falls and other activities that can cause a fracture. Teach the patient about the importance of having a hazard-free environment, including avoiding scatter rugs, cluttered rooms, and wet floor areas.

Hospitals and long-term care facilities have risk management programs to assess for the risk for falls. For those patients at high risk, communicate this information to other members of the health care team, using colored armbands or other easy-to-recognize methods (National Patient Safety Goals). Chapter 3 discusses fall prevention in health care agencies and at home in more detail.

Nclex Examination Challenge

Health Promotion and Maintenance

Which statement by the client regarding lifestyle changes to prevent osteoporosis indicates a need for further teaching by the nurse?

A. “I need to eat more green, leafy vegetables and dairy products.”

B. “I will cut down the amount of wine I drink each night.”

C. “I plan to begin smoking cessation classes at the hospital.”

D. “I am going to want to work out 3 days a week at the gym.”

Drug Therapy

The health care provider may prescribe calcium and vitamin D supplements, bisphosphonates, or estrogen agonist/antagonists (formerly called selective estrogen receptor modulators), or a combination of several drugs to treat or prevent osteoporosis (Chart 53-2). Estrogen and combination hormone therapy are not used solely for osteoporosis prevention or management because they can increase other health risks such as breast cancer and myocardial infarction (Woman’s Health Initiative, 2005).

Chart 53-2 Common Examples of Drug Therapy

Osteoporosis

Calcium and Vitamin D

Intake of calcium alone is not a treatment for osteoporosis, but calcium is an important part of a prevention program to promote bone health. Most people cannot or do not have enough calcium in their diet, and therefore calcium supplements are needed. Calcium carbonate, found in over-the-counter (OTC) drugs such as Os-Cal, is one of the most cost-effective supplement formulas. Calcium citrate, available OTC as Citracal, is often recommended for those who have gastric upset when taking a calcium supplement. Teach patients to take calcium supplements with food and 6 to 8 ounces of water, although Citracal can be taken anytime. It is best to divide the daily dose, with at least one third of the daily dose being taken in the evening. Teach women to start taking supplements in young adulthood to assist in maintaining peak bone mass. Instruct patients of any age to take calcium supplements that also contain activated vitamin D, such as Os-Cal Ultra.

Remind patients to take these supplements under the supervision of a health care provider. Hypercalcemia (excess serum calcium) can cause serious damage to the urinary system and other body systems. Teach patients to drink plenty of fluids to prevent urinary or renal calculi (stones). Chapter 13 describes the clinical manifestations of hypercalcemia.

Bisphosphonates

Bisphosphonates (BPs) slow bone resorption by binding with crystal elements in bone, especially spongy, trabecular bone tissue. They are the most common drugs used for osteoporosis, but some are also approved for Paget’s disease and hypercalcemia related to cancer. Three FDA-approved BPs—alendronate (Fosamax), ibandronate (Boniva), and risedronate (Actonel)—are commonly used for the prevention and treatment of osteoporosis (National Osteoporosis Foundation, 2010). These drugs are available as oral preparations, with ibandronate (Boniva) also available as an IV preparation.

Nursing Safety Priority

Drug Alert

Do not confuse Fosamax with Flomax, a selective alpha-adrenergic blocker used for benign prostatic hyperplasia (BPH).

Oral BPs are commonly associated with a serious problem called esophagitis (inflammation of the esophagus). Esophageal ulcers have also been reported with the use of BPs, especially when the tablet is not completely swallowed.

Nursing Safety Priority

Drug Alert

Teach patients to take bisphosphonates (BPs) early in the morning with 8 ounces of water and wait 30 to 60 minutes in an upright position before eating. If chest discomfort occurs, a symptom of esophageal irritation, instruct patients to discontinue the drug and contact their health care provider. Patients with poor renal function, hypocalcemia, or gastroesophageal reflux disease (GERD) should not take BPs.

The most recent additions to the bisphosphonates are IV zoledronic acid (Reclast) and IV pamidronate (Aredia). For management of osteoporosis, Reclast is needed only once a year and Aredia is given every 3 to 6 months. Both drugs have been linked to a complication called jaw osteonecrosis (jaw bone death) in which infection and necrosis of the mandible or maxilla occur (Lee, 2009). The incidence of this serious problem is low but can be a complication of this infusion therapy.

Nursing Safety Priority

Drug Alert

Teach the patient to have an oral assessment and preventive dentistry before beginning any bisphosphonate therapy. Instruct the patient to inform any dentist who is planning invasive treatment, such as a tooth extraction or implant, that he or she is taking a BP (Cohen, 2010).

Estrogen Agonist/Antagonists

Formerly called the selective estrogen receptor modulators (SERMs), estrogen agonist/antagonists are a class of drugs designed to mimic estrogen in some parts of the body while blocking its effect elsewhere. Raloxifene (Evista) is currently the only approved drug in this class and is used for prevention and treatment of osteoporosis in postmenopausal women. Raloxifene increases bone mineral density (BMD), reduces bone resorption, and reduces the incidence of osteoporotic vertebral fractures. The drug should not be given to women who have a history of thromboembolism.

Other Agents

Parathyroid hormone is prepared as teriparatide under the brand name Forteo and is a bone-building agent approved for treatment of osteoporosis in postmenopausal women with high risk for fracture. Teach patients to self-administer Forteo as a daily subcutaneous injection. This drug stimulates new bone formation, thus increasing BMD. Reduced risk for fracture in the spine, hip, and wrist has been reported in women, and reduced risk for hip fracture has been reported in men. Patients may experience dizziness or leg cramping as side effects of Forteo (National Osteoporosis Foundation, 2010). Teach the patient to lie down if these problems occur and notify the health care provider as soon as possible.

Calcitonin is a thyroid hormone that inhibits osteoclastic activity, thus decreasing bone loss. It is used for the treatment of osteoporosis, Paget’s disease, and hypercalcemia associated with cancer. The drug also has an analgesic effect after vertebral fracture, thereby promoting early recovery.

Calcitonin can be given subcutaneously or intranasally. The nasal route is preferred because it improves drug adherence, decreases side effects, and is convenient. However, the effect of calcitonin may decrease after use for 2 or more years. Patients may require a holiday from this treatment to maintain effectiveness. Teach the patient to alternate nares to prevent mucosal irritation, a common side effect. The drug must be refrigerated.

Decision-Making Challenge

Patient-Centered Care; Evidence-Based Practice

A 62-year-old patient visits the physician’s office to receive her first treatment for osteoporosis. She has a recent history of a badly fractured ankle and osteopenia (for which she has been taking Actonel). Her mother and grandmother had osteoporosis and osteoarthritis. The patient does not smoke but enjoys an occasional glass of wine when she and her husband go out for dinner. She drinks only 1 or 2 cups of caffeinated beverages a day. Although she realizes the importance of regular exercise, she has no time to fit that into her schedule because she travels throughout the country for her job. As her office nurse, you will be monitoring her as she has her first dose of Reclast.

1. What risk factors does this patient have for osteopenia and osteoporosis?

2. What health teaching might this patient need? How can you help her plan time for increasing her physical activity level? What does current evidence show that supports your answer?

3. What actions will you take before starting her Reclast?

4. How fast will you administer the drug, and what method will you use?

Community-Based Care

Patients with osteoporosis are usually managed at home. Osteoporosis disease-management programs managed by nurse practitioners have helped diagnose and treat the disease. Greene and Dell (2010) reported that over a 6-year period, a large osteoporosis disease-management program resulted in a 263% increase in the number of DXA scans done each year, a 153% increase in the number of patients treated with drug therapy, and a 38.1% decrease in the expected hip fracture rate.

Some patients have fractures that may require hospitalization or medical management in an emergency department (ED) or urgent care setting. In any setting, assess for risk factors for osteoporosis and provide health teaching as appropriate.

The patient with osteoporosis who has one or more fractures may be discharged to the home setting. In some instances, though, the patient is transferred to a long-term care facility for rehabilitation or permanent residence when support systems are not available. Collaborate with case managers or discharge planners to assist in preparing patients and their families for placement in long-term care facilities. Chapter 54 discusses continuing care for patients who have fractures.

Refer patients to the National Osteoporosis Foundation (www.nof.org) in the United States to provide information to patients and health care professionals regarding the disease and its treatment. The Osteoporosis Society of Canada (www.osteoporosis.ca) has similar services. Large hospitals often have osteoporosis specialty clinics and support groups for patients with osteoporosis.

Osteomalacia

Pathophysiology

Osteomalacia is loss of bone related to a vitamin D deficiency. It causes softening of the bone resulting from inadequate deposits of calcium and phosphorus in the bone matrix. Normal remodeling of the bone is disrupted, and calcification does not occur. Osteomalacia is the adult equivalent of rickets, or vitamin D deficiency, in children.

Vitamin D deficiency is the most important factor in development of osteomalacia. In its natural form, vitamin D is activated by the ultraviolet radiation of the sun and obtained from certain foods as a nutritional supplement. In combination with calcium and phosphorus, the vitamin is necessary for bone formation.

Osteomalacia is frequently confused with osteoporosis because of similar characteristics shared by the two disease processes. Table 53-2 compares and contrasts osteoporosis and osteomalacia.

TABLE 53-2 DIFFERENTIAL FEATURES OF OSTEOPOROSIS AND OSTEOMALACIA

CHARACTERISTIC	OSTEOPOROSIS	OSTEOMALACIA
Definition	Decreased bone mass	Demineralized bone
Pathophysiology	Lack of calcium	Lack of vitamin D
Radiographic findings	Osteopenia, fractures	Pseudofractures, Looser’s zones, fractures
Calcium level	Low or normal	Low or normal
Phosphate level	Normal	Low or normal
Parathyroid hormone	Normal	High or normal
Alkaline phosphatase	Normal	High