Bone Disease

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A variety of diseases affect bones. One of the most common bone diseases is osteoporosis, which is characterized by a thinning of bone tissue, causing bones to become weak, brittle, and prone to fractures. Many factors can cause osteoporosis, including menopause, lack of exercise, low calcium intake, smoking, use of steroid drugs, and excessive consumption of alcohol.

Dietary deficiencies of calcium, phosphorus, and vitamin D cause rickets, a disease characterized by abnormal bone formation and skeletal deformities. Rickets is most common in children. Dietary deficiencies of these nutrients in adults-or metabolic disorders that cause poor absorption of the nutrients-can result in an abnormal softening of bone, a condition called osteomalacia.

Infections of bones called osteomyelitis usually are caused by bacteria, especially Staphylococcus, which enters the body through open wounds and may destroy bone tissues. Tumors, or abnormal growths, occur in bone tissue, though most are benign. Cancerous tumors can be caused by excessive radiation; many radioactive substances have an affinity for bone, particularly the marrow, and are readily stored there. Most cancerous tumors in bones, however, are tumors that spread from cancer in other parts of the body. Cancers that arise in bone, cartilage, and other connective tissues are called sarcomas.

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