title: Influence of age, sex and weight on measurements of intracellular Na+ and K+ in essential hypertension.
abstract: Na+ and K+ concentrations were measured in red cells from 22 patients with untreated essential hypertension and 22 normotensive control subjects who were individually and prospectively matched for age, sex and weight and in a separate population of 31 hypertensive patients and 41 normotensive subjects who were not so matched. Intracellular Na+ and K+ concentrations were similar in the matched subjects. Significant positive correlations were found between intracellular Na+ and body weight (r = 0.27, P less than 0.041), and between intracellular K+ and age (r = 0.29, P less than 0.028). In the unmatched population, intracellular Na+ was significantly increased in patients with hypertension and was correlated significantly with age (r = 0.25, P less than 0.017). After correction for age, intracellular Na+ was similar in both hypertensive and normotensive subjects. Age-corrected intracellular K+ was similar in both hypertensive and normotensive groups but was significantly lower in male subjects. These results highlight the importance of matching study groups for age, sex and weight when studying possible abnormalities in cell ionic composition in hypertension. False positive results may arise if study groups are not matched for these characteristics. Red cell Na+ and K+ are not altered in essential hypertension.
mesh_terms: D000367:Age Factors; D001835:Body Weight; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood*; D008297:Male; D011188:Potassium / Q000097:blood*; D012737:Sex Factors; D012964:Sodium / Q000097:blood*
chemical_list: D012964:Sodium; D011188:Potassium