[Determination of blood pressure sensitivity to salt]

Considerable evidence has accumulated indicating that sodium sensitivity of blood pressure is an important prognostic factor in hypertension. This review article focuses on methods used to define salt sensitivity in man. The linear approximation of pressure-natriuresis curve has made it possible to elaborate reliable non-invasive approaches for distinguishing salt-sensitive from salt-resistant forms of human hypertension. The sodium sensitivity index, calculated as the ratio of the change in mean arterial pressure over the change in natriuresis, can be calculated to characterize hypertension. Literary data show that salt sensitivity increases with age and that more salt-sensitive persons exist among hypertensive than among normotensive individuals (about 40-50% vs. 25-40%, respectively, provided the daily salt does not exceed 25 g).