Mechanisms of hypertension associated with obesity.

Epidemiologic studies suggest that obesity is a major factor in hypertension in industrialized societies. Possible mechanisms for this association include elevated cardiac output, increased body sodium due to hyperinsulinemia or abnormal aldosterone/renin relationships, and neuroendocrine abnormalities due to increased noradrenergic activity or opiate suppression. Although cardiac output and plasma volume of obese hypertensive patients are not different from what is found in non-obese persons when expressed in relation to body surface area, these results are from cross-sectional studies and do not relate to the effects of weight gain on arterial pressure. The role of hyperinsulinemia and that of other endocrine or neuroendocrine abnormalities have not been studied extensively enough for the association to be proved.