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Orthostatic hypertension, or postural hypertension, is a medical condition consisting of a sudden increase in blood pressure when a person stands up. Orthostatic hypertension is diagnosed by a rise in systolic blood pressure of 20 mmHg or more when standing. ''Orthostatic diastolic hypertension'' is a condition in which the diastolic raises to 98 mmHg or over in response to standing; however, this definition currently lacks clear medical consensus and is thus subject to change. Orthostatic hypertension involving the systolic is known as ''systolic orthostatic hypertension''. If affecting an individual's ability to remain upright, orthostatic hypertension is viewed as a form of orthostatic intolerance. The body's inability to regulate the blood pressure can be a type of dysautonomia. Baroreflex and autonomic pathways normally ensure that blood pressure is maintained despite various stimuli including postural change. The precise mechanism of orthostatic hypertension remains unclear, but it is thought that alpha-adrenergic activity may be the predominant pathophysiologic mechanism of orthostatic hypertension in elderly hypertensive patients. Other mechanisms are proposed for other different groups of individuals with this disorder.〔 A prevalence of 1.1% was found in a large population study. The risk of orthostatic hypertension has been found to increase with age, with it being found in 16.3% of older hypertensive patients. ==Symptoms== * Mild or moderate orthostatic hypertension may present without any symptoms other than the orthostatic hypertension BP findings. More severe orthostatic hypertension may present with the typical symptoms of hypertension. * Orthostatic venous pooling is common with orthostatic diastolic hypertension. This occurs in the legs while standing. * Hypovolemia (decreased blood volume) 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「Orthostatic hypertension」の詳細全文を読む スポンサード リンク
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