Sodium sensitivity: a determinant of essential hypertension.

The epidemiologic correlation of chronic dietary salt intake among populations with the prevalence of hypertension has resulted in the concept that sodium plays an etiologic role in the development of essential hypertension (EH). However, the association of sodium intake with blood pressure in individuals within populations has been difficult to demonstrate. The differing human responses to sodium intake are dependent upon the individual level of sodium sensitivity or sodium resistance. Factors associated with sodium sensitivity are race, age, and other dietary factors. More recent investigations have pursued the interaction of sodium intake with other physiologic parameters including neurogenic activity, vascular structure, renal function, and other cations such as potassium and calcium. The observations that some humans demonstrate very little increase in blood pressure despite high levels of sodium intake supports the concept that a high sodium intake alone is not a single causal factor in hypertension. Sodium intake appears to interact with renal excretory capacity and vascular compliance. These varying physiologic functions must be delineated to characterize sodium sensitivity.