Urinary electrolytes, body weight, and blood pressure. Pooled cross-sectional results among four groups of adolescent females.

Abstract

SUMMARY Results of blood pressure (BP) and urinary electrolyte excretion studies are reported among several groups of adolescent and young adult females, both black and white, who were Initially examined in high school and restudied at home 3-4 years later. Pooling of the data from the sereral cross-cectional studies (n = 662) rerealed a weak but statistically significant positive correlation between systolic blood pressure (SBP) and the urinary sodium (Na) excretion rate. Three of four correlations between SBP and potassium (K) were of an inverse nature. Although not statistically significant in their own right, when coupled with the Na/K excretion ratio, which was significantly associated with SBP, a moderating role for K b suggested. The urinary Na, K, and creatinine (Cr) excretion rates were highly intercorrelated and were correlated with weight. As measured by R 1 in a stepwise regression analysis, weight contributed approximately 3% to the BP variance, and the urinary electrolytes accounted for approximately 2% of the SBP variance. Statistically significant partial correlation coefficients between SBP and Na, and Na/K, remained after adjusting for body weight. T HERE is much experimental evidence to suggest that the ingestion of high levels of sodium (Na) may play a role in the genesis of high blood pressure (BP) among several species of laboratory animals. The evidence for such a relationship among human populations, however, is equivocal. Human studies that have tried to show a direct association between urinary electrolyte excretion rates and BP utilizing cross-sectional data have been largely unsuccessful.

Diet and blood pressure in children

“…In observational studies [41,42] using urinary magnesium as a measure of dietary intake, one showed a significant inverse relation [42]. Likewise, higher intakes of dietary potassium in children have been associated with lower systolic [43] and diastolic [44,45] blood pressure. However, results of one study indicated the opposite effect [46].…”

Diet and blood pressure in children and adolescents

“…Of the 9 urinary potassium studies, ranging in sample size from 73 to 445, 6 controlled for other variables including body size [21 -25, 27]. Two found significant inverse associations between urinary potassium and BP -1 with DBP [24] and the other with lower annual slope of change in SBP over 7 years [25] -and 1 found a significant positive association between potassium excretion and SBP [23]. Three of the studies that controlled for other variables found no significant association [21,22,27].…”

“…Three of the studies found no association between sodium and BP [21,22,27], and 3 found a significant positive association between sodium and SBP [23,24] or both SBP and DBP [26]. One of the studies analyzed data longitudinally and controlled for weight, sex, age, height, and other electrolytes; there was no significant association between sodium excretion and annual slope of BP change calculated from 7 years of data, although there was a significantly higher rate of increase in SBP with higher sodium/potassium ratio [25].…”

Gastrointestinal and renal excretion of potassium in African–Americans and White Americans

“…A substantial body of evidence demonstrates that cumulative urinary excretion of K þ is significantly less in African-Americans than White Americans on both random diets [1][2][3][4][5][6][7][8][9][10][11] and diets fixed for K þ content [2,[12][13][14][15]. The explanation for this remarkable observation, however, has remained totally obscure but is consistent with the hypothesis that African-Americans are in a state of relative K þ deficiency when compared with White Americans.…”