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Osteomalacia is the softening of the bones caused by defective bone mineralization secondary to inadequate levels of available phosphate and calcium, or because of overactive resorption of calcium from the bone which can be caused by hyperparathyroidism (which causes hypercalcemia).〔(TheFreeDictionary > osteomalacia ) Citing: Mosby's Medical Dictionary, 8th edition. Copyright 2009〕 Osteomalacia in children is known as rickets, and because of this, use of the term "osteomalacia" is often restricted to the milder, adult form of the disease. Signs and symptoms can include diffuse body pains, muscle weakness, and fragility of the bones. The most common cause of osteomalacia is a deficiency of vitamin D, which is normally derived from sunlight exposure and, to a lesser extent, from the diet.〔(MedlinePlus Medical Encyclopedia: Osteomalacia )〕 The most specific screening test for vitamin D deficiency in otherwise healthy individuals is a serum 25(OH)D level. Less common causes of osteomalacia can include hereditary deficiencies of vitamin D or phosphate (which would typically be identified in childhood) or malignancy. Measures to prevent and treat osteomalacia usually revolve around intake of vitamin D and calcium supplements. Vitamin D should always be administered in conjunction with calcium supplementation since most of the consequences of vitamin D deficiency are a result of impaired mineral ion homeostasis. Nursing home residents and the homebound elderly population are at particular risk for vitamin D deficiency, as these populations typically receive little sun exposure. In addition, both the efficiency of vitamin D synthesis in the skin and the absorption of vitamin D from the intestine decline with age, thus further increasing the risk in these populations. Other groups at risk include individuals with malabsorption secondary to gastrointestinal bypass surgery or celiac disease, and individuals who immigrate from warm climates to cold climates, especially women who wear traditional veils or dresses that prevent sun exposure. ==Signs and symptoms== Osteomalacia is a generalized bone condition in which there is inadequate mineralization of the bone. Many of the effects of the disease overlap with the more common osteoporosis, but the two diseases are significantly different. There are two main causes of osteomalacia: (1) insufficient calcium absorption from the intestine because of lack of dietary calcium or a deficiency of, or resistance to, the action of vitamin D; and (2) phosphate deficiency caused by increased renal losses. *Diffuse joint and bone pain (especially of spine, pelvis, and legs) *Muscle weakness *Difficulty walking, often with waddling gait *Hypocalcemia (positive Chvostek sign) *Compressed vertebrae and diminished stature *Pelvic flattening *Weak, soft bones *Easy fracturing *Bending of bones Osteomalacia in adults starts insidiously as aches and pains in the lumbar (lower back) region and thighs before spreading to the arms and ribs. The pain is symmetrical, non-radiating and accompanied by sensitivity in the involved bones. Proximal muscles are weak, and there is difficulty in climbing up stairs and getting up from a squatting position. As a result of demineralization, the bones become less rigid. Physical signs include deformities like triradiate pelvis and lordosis. The patient has a typical "waddling" gait. However, these physical signs may derive from a previous osteomalacial state, since bones do not regain their original shape after they become deformed. Pathologic fractures due to weight bearing may develop. Most of the time, the only alleged symptom is chronic fatigue, while bone aches are not spontaneous but only revealed by pressure or shocks. It differs from renal osteodystrophy, where the latter shows hyperphosphatemia. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「osteomalacia」の詳細全文を読む スポンサード リンク
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