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Orthostatic hypertension is a medical condition consisting of a sudden and abrupt increase in blood pressure when a person stands up. Orthostatic hypertension is diagnosed by a rise in systolic BP of 20 mmHg or more when standing. Orthostatic diastolic hypertension is a condition in which the diastolic BP raises to 98 mmHg or over in response to standing, but this definition currently lacks clear medical consensus, so is subject to change. Orthostatic hypertension involving the systolic BP 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 BP 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 alpha-adrenergic activity may be the predominant pathophysiologic mechanism of orthostatic hypertension in elderly hypertensive patients. Other mechanisms are proposed for other groups 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.