Electrolyte output, blood pressure, and family history of hypertension

Adult, normotensive subjects were divided into two groups on the basis of whether their first degree relatives were diagnosed as being hypertensive. Urine samples were collected over a 24-hr period for 3 days and analyzed for electrolyte excretion; the rate of electrolyte excretion was also measured separately during the overnight period. Significant correlations were shown between blood pressure and sodium and chloride excretion, both the 24-hr total and the overnight rate; Na/K ratio; weight; and body mass index for those subjects with a positive family history of hypertension. In subjects with no family history of hypertension there were no significant correlations between those parameters and blood pressure. The rate of urinary excretion of sodium overnight may provide a means for further studies on populations to determine the interrelationship between sodium excretion, other parameters, blood pressure, and family history of hypertension.