A genetically determined alteration of the cell membrane sodium metabolism may play a role in the pathogenesis of essential hypertension. The most consistent finding in patients with essential hypertension is an increased red blood cell Li/Na exchange (countertransport). It is genetically determined but it is also associated to potentially confounding variables (body weight, race, age and so on). The present study investigates the relationship between red cell Li/Na countertransport and various potentially confounding variables in a random sample of the population. It shows that this membrane cation transport system is increased in males compared to females and significantly correlated to body mass index in males and to blood pressure, alcohol consumption and, negatively, to urinary calcium excretion in females. Since body weight and alcohol consumption are correlated to blood pressure in several epidemiological studies, it can be hypothesized that they influence blood pressure control through an alteration of the cell membrane sodium transport.