Salt sensitivity in hypertension: implications for the kidney

The role of dietary sodium in the pathogenesis of essential hypertension has stimulated a great deal of interest and investigation in recent years. There are epidemiologic studies in the literature that suggest a link between dietary sodium intake and the prevalence of hypertension. However, not all patients are prone to the development of hypertension in response to dietary sodium. Therefore, a distinction between salt sensitivity and salt-resistant essential hypertension has evolved from this observation. The mechanisms which related dietary sodium to the pathogenesis of essential hypertension are not clearly defined, although it appears that inborn errors of renal sodium handling, along with certain components of the sympathetic nervous system, may be involved. Furthermore, intracellular sodium and its transport mechanisms have been implicated in the pathogenesis of hypertension associated with dietary sodium. Finally, there appears to be a correlation between dietary sodium, salt sensitivity, and the progression of renal disease. That is to say, patients with salt-sensitive essential hypertension appear to demonstrate a more relentless course to end-stage renal disease. This tendency may be related to deranged hemodynamic adaptation of the renal circulation in response to dietary sodium intake and the resulting rise in systemic blood pressure. The mechanism for this derangement of renal hemodynamic adaptation in salt-sensitive hypertensives remains to be determined.