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List of All Topics
Osteomalacia
Introduction
Osteomalacia refers to a softening of your bones, most often caused by a vitamin D deficiency. In children, this condition is called rickets. Soft bones are more likely to bow and fracture than are harder, healthy bones. Achy bone pain and muscle weakness are the major signs and symptoms of osteomalacia.
Osteomalacia often develops if you're not exposed to enough sunlight because sunlight prompts the production of vitamin D in your skin. A diet deficient in vitamin D and disorders that interfere with the absorption of vitamin D in your digestive tract also are major causes of osteomalacia.
Osteomalacia is not the same as osteoporosis, another bone disorder that can also lead to bone fractures. Osteomalacia results from a defect in the bone-building process, while osteoporosis develops due to a weakening of previously constructed bone.
Treatment for osteomalacia involves replenishing low levels of vitamin D and other bone-building minerals or treating an underlying disorder that may be causing osteomalacia.
Signs and symptoms
In the early stages, you may have no osteomalacia symptoms, although signs of osteomalacia may be apparent on X-ray pictures or other diagnostic tests. As osteomalacia worsens, symptoms may include:
- Bone pain. People with osteomalacia often experience pain in their bones, especially in the lower spine, pelvis and legs and feet. Pain associated with osteomalacia is usually dull and aching and worsens during physical activity. You might notice that gently pressing on a bone — on your shin, for example — produces severe pain.
- Muscle weakness. Osteomalacia can cause weakness or stiffness in your arms and legs, decreased muscle tone and discomfort while moving. Some people with osteomalacia walk with a waddling motion.
Even as an adult, your bones are undergoing constant remodeling. At any moment, small areas of bone in your body are being broken down by specialized cells called osteoclasts and rebuilt by cells called osteoblasts.
Bone construction begins with a base composed of collagen, a fibrous connective tissue. As bone is formed, collagen fibers adhere to each other in a crisscross pattern (matrix). Then minerals, including calcium, are incorporated into the matrix in a process called mineralization. The strength of new bone depends on the amount of minerals incorporated into the matrix: The more minerals built into the matrix, the stronger the bone.
Usually, the cause of osteomalacia is a deficiency in vitamin D. Vitamin D insufficiency can cause osteomalacia because vitamin D facilitates the absorption of calcium and other minerals in your gastrointestinal tract necessary for bone building. Without vitamin D, calcium and other minerals aren't absorbed as readily, so they're not available for mineralization in the bone-building process. This results in "soft" bones — called osteomalacia.
Causes of vitamin D deficiency include:
- Insufficient exposure to sunlight. Sunlight produces vitamin D in your skin. Osteomalacia can develop in people who spend little time in sunlight, wear very strong sunscreen, remain covered while outside, or live in areas where sunlight hours are short or the air is smoggy.
- Insufficient vitamin D intake. A diet low in vitamin D is the most common cause of osteomalacia worldwide. However, it's a less common cause in the United States because many foods, such as milk and cereals, are fortified with vitamin D.
- Certain surgeries. Removing part or all of your stomach (gastrectomy) can cause osteomalacia because your stomach breaks down foods to release vitamin D and other minerals, which are absorbed in your intestines. Surgery to remove or bypass your small intestine also can lead to osteomalacia.
- Celiac sprue. In this autoimmune disorder, the lining of your small intestine is damaged by consuming foods containing gluten, a protein found in wheat, barley and rye. A damaged intestinal lining doesn't absorb nutrients, such as vitamin D, as well as a healthy one does.
- Chronic pancreatitis. This refers to long-standing inflammation of your pancreas, an organ that produces digestive enzymes and hormones. If your pancreas is inflamed, enzymes responsible for breaking down food and releasing nutrients don't flow as freely into your intestines.
- Familial X-linked hypophosphatemia. This rare genetic disorder interferes with your kidneys' ability to absorb phosphorus into your bloodstream.
- Kidney disorders. Several kidney disorders, including renal tubular acidosis and Faconi syndrome, cause phosphorus and other substances to be excreted in your urine instead of being absorbed normally into your bloodstream.
- Tumor-associated osteomalacia. Some types of cancers secrete a substance that affects your kidneys' ability to absorb phosphorus, causing osteomalacia.
Treatment
When osteomalacia arises from a dietary or sunlight deficiency, replenishing low levels of vitamin D in your body usually cures the condition. Several types of vitamin D supplements are available, so your doctor will probably recommend a supplement depending on the dose you need and whether you have any other health problems. Generally, people with osteomalacia take vitamin D supplements by mouth for a period of several weeks to several months. Less commonly, vitamin D is given as an injection or through a vein in your arm.
If your blood levels of calcium or phosphorus are low, you may take supplements of those minerals as well. In addition, treating any condition affecting vitamin D metabolism, such as kidney failure or primary biliary cirrhosis, often helps improve the signs and symptoms of osteomalacia.
After beginning osteomalacia treatment, you may undergo periodic blood tests to make sure that blood levels of vitamin D and certain minerals are within normal limits and have X-rays to determine whether your bones are improving. You'll likely notice that your symptoms lessen within a few weeks. However, your doctor may suggest that you continue taking vitamin D indefinitely to prevent osteomalacia from recurring.
Prevention
Osteomalacia caused by inadequate sun exposure or a diet low in vitamin D often can be prevented. Here are a few suggestions to help reduce your risk of developing osteomalacia:
- Spend a few minutes in the sun. Direct sun exposure to your arms and legs for five to 10 minutes daily is sufficient for proper vitamin D production. If you live in a cold climate and don't get much sun exposure during the winter, you can build up vitamin D stores in your skin during the warmer months.
Using sunscreen regularly helps prevent skin cancer and premature skin aging, but there's some concern that the frequent application of strong sunscreen increases your risk of developing osteomalacia. Using sunscreen won't increase your risk if you follow the American Academy of Dermatology's guidelines for sunscreen use. If you're going to be in the sun for more than 20 minutes, the Academy recommends that you generously apply sunscreen with a sun protection factor (SPF) of at least 15 to all exposed skin surfaces and reapply every two hours or after swimming or heavy sweating. - Eat foods high in vitamin D. These include foods that are naturally rich in vitamin D, including oily fish (salmon, mackerel, sardines) and egg yolks. If you're a vegetarian, look for foods that are fortified with vitamin D, such as cereal, bread, milk and yogurt.
- Take supplements, if needed. If you don't get enough vitamins and minerals in your diet or if you have a medical condition affecting the ability of your digestive system to absorb nutrients properly, ask your doctor about taking vitamin D and calcium supplements.
Information obtained from National Institute of Health