Osteomalacia

Overview

Osteomalacia is the general term for the softening of the bones due to defective bone mineralization. Osteomalacia in children is known as rickets, and because of this, osteomalacia is often restricted to the milder, adult form of the disease. It may show signs as diffuse body pains, muscle weakness, and fragility of the bones. A common cause of the disease is a deficiency in Vitamin D, which is normally obtained from the diet and/or sunlight exposure.

Symptoms

* Diffuse (not pinpointed to one location) bone pain, especially in the hips * Muscle weakness * Bone fractures that happen with very little trauma Symptoms associated with low calcium including: * Numbness around the mouth * Numbness of extremities * Spasms of hands or feet * Abnormal heart rhythms

Causes

There are numerous causes of osteomalacia. In children, the condition is called rickets and is usually caused by a deficiency of vitamin D. Conditions that may lead to osteomalacia include: * Not enough vitamin D in the diet * Not enough exposure to sunlight, which produces vitamin D in the body * Malabsorption of vitamin D by the intestines Other conditions that may cause osteomalacia include: * Hereditary or acquired disorders of vitamin D metabolism * Kidney failure and acidosis * Phosphate depletion associated with not enough phosphates in the diet * Cancer * Side effects of medications used to treat seizures * Liver disease Use of very strong sunscreen, limited exposure of the body to sunlight, short days of sunlight, and smog are factors that reduce formation of vitamin D in the body. Risk factors for osteomalacia are related to the causes. In the elderly, there is an increased risk among people who tend to remain indoors and those who avoid milk because of lactose intolerance.

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.

Diagnosis

* Bone biopsy shows osteomalacia. * Serum vitamin D level may be low. * Serum calcium levels vary with the cause of the disorder. * Serum phosphate levels vary with the cause of the disorder. * Bone x-ray may show features of osteomalacia (such as bowing of the legs or “pseudofractures"). * Bone mineral density scan (DEXA) may show reduced bone density, a sign of weaker bones. Other tests may be done to determine if there is a renal problem or any other underlying disorder. These tests include: * PTH * Calcium (ionized) * ALP (alkaline phosphatase) isoenzyme

Prognosis

Improvement in the condition of the bones, shown by bone X-rays, can be seen within a few weeks in some people with vitamin deficiency disorders. Complete healing with treatment takes place in 6 months.

Treatment

Oral supplements of vitamin D, calcium, and phosphorus may be given depending on the underlying cause of the disorder. Larger doses of vitamin D and calcium may be needed for people with intestinal malabsorption. Monitoring the blood levels of phosphorus and calcium may be needed for people with certain underlying conditions.