Serum sodium and potassium in essential hypertension.

DIFFERENCES have been noted between normotensive and hypertensive individuals in salt intake,' intracellular electrolytes,2 total body electrolytes,3 serum electrolytes,4 and the renal excretion of sodium and water.5 If changes in serum sodium concentration reflected intracelluar or metabolic alterations in electrolyte balance, an easily determined factor would be available for study of electrolyte abnormalities in relation to the development of hypertension. Three investigators have reported a slight increase in serum sodiumn concentration in patients with essential hypertension,4 6 T whereas two other studies report no difference.8 9 The purpose of this study was to define more accurately the associations between serum sodium, serum potassium, and blood pressure level by standardizing to the greatest degree possible all methods and measurements, and by assessing the importance of such variables as age, sex, and body build. An additional purpose was to evaluate further the relationship of stated salt intake to blood pressure level and serum electrolyte concentrations.