Changing position from sitting to standing normally causes a slight drop in systolic blood pressure that is quickly remedied through a series of minute cardiovascular adjustments. In 5 percent of the population, however, moving to a standing posture elicits an exaggerated rise in systolic blood pressure of at least 20mmHg, according to the Journal of Cardiovascular Pharmacology. This altered response is termed orthostatic hypertension and has been linked to stroke and type 2 diabetes.
Pressure Regulation
Assuming the standing position causes a rise in circulating neurotransmitters and hormones that work in combination to constrict blood vessels. This constriction maintains normal blood pressure and is controlled by baroreceptors, which are pressure sensors that monitor changes in the body's blood pressure. Nature Clinical Practice Nephrology published a review of orthostatic hypertension that concluded that while the cause of orthostatic hypertension is not clearly understood, one prominent hypothesis links the exaggerated blood pressure response to malfunctioning baroreceptors. In patients with orthostatic hypertension, moving from sitting to standing elicits a much greater activation of the baroreceptors and causes the release of an abundance of neurotransmitters and hormones. As a result, the blood vessels constrict to a greater degree than necessary, and the blood pressure response becomes amplified.
Stroke
A 2010 report in the American Journal of Hypertension showed a significant association between the incidence of silent strokes and orthostatic hypertension. Of the 770 subjects with orthostatic hypertension, 14.3 percent suffered from strokes. As severity of orthostatic hypertension increased, so did the incidence of stroke. Likewise, research in the Journal of the American College of Cardiology indicated 81 percent of subjects studied with known orthostatic hypertension had incurred at least one silent stroke, and 65 percent had had three or more.
Type 2 Diabetes
Type 2 diabetes and orthostatic hypertension have shown a strong association. According to the scientific journal Diabetes Care, nearly 13 percent of the type 2 diabetic patients studied displayed orthostatic hypertension when changing posture. Notably, 12.8 percent of the diabetic patients that displayed orthostatic hypertension were not hypertensive at rest. In contrast, only 1.8 percent of nondiabetic subjects with normal resting blood pressure experienced orthostatic hypertension. This suggests that orthostatic dysfunction is independent of resting blood pressure and that type 2 diabetes compounds this existence. A further finding indicated that patients with type 2 diabetes have a five-fold higher prevalence of orthostatic hypertension than nondiabetic individuals, regardless of resting blood pressure response.
References
- "Journal of Cardiovascular Pharmacology"; Experimental Orthostasis Elicits Sustained Hypertension; Gabor Raffai, MSc; 2005
- Nature Clinical Practice Nephrology: Orthostatic Hypertension-When Pressor Reflexes Overcompensate
- "American Journal of Hypertension"; Disorders of Orthostatic Blood Pressure Response Are Associated with Cardiovascular Disease and Target Organ Damage in Hypertensive Patients; Xiao-Han Fan, Ph.D.; 2010
- Journal of the American College of Cardiology: U-Curve Relationship Between Orthostatic Blood Pressure Change and Silent Cerebrovascular Disease in Elderly Hypertensives
- "Diabetes Care"; Orthostatic Hypertension in Patients with Type II Diabetes; Mototaka Yoshinari, M.D., Ph.D.; 2001
