Hypertension in blacks.

In the United States, blacks have higher blood pressure levels than whites at all ages, a finding that cannot be explained solely by differences in body habitus. A European population survey reported similar differences. Several physiologic mechanisms have been evaluated, including sodium sensitivity and insulin resistance. Although it is often stated that blacks show a greater blood pressure reactivity than whites, recent data are conflicting, and such differences may be attributable to family history of hypertension. The physiologic mechanisms underlying any reactivity differences could be structural changes in the resistance vessels. Blacks tend to show smaller falls of nocturnal blood pressure than whites, and this could be related to the observation of a greater degree of left ventricular hypertrophy seen in blacks for a given level of clinic blood pressure. Severe left ventricular hypertrophy may be associated with functional myocardial ischemia, even in the absence of epicardial coronary artery disease. Renal damage is also more pronounced in blacks than in whites.