ELECTROLYTES ARE ASSOCIATED WITH BLOOD-PRESSURE AT OLD-AGE - THE ROTTERDAM STUDY

We examined the association of urinary sodium and potassium excretion with blood pressure (BP) in the Rotterdam Study, a population-based st udy among 7983 men and women aged 55 and over. The present analysis in cluded 1006 subjects with complete BP and urinary data who did not use antihypertensive drugs and did not report themselves to be hypertensi ve. Electrolyte excretions were assessed in a timed nocturnal urine sa mple and standardized to 24-h values. The association of electrolyte e xcretions with BP was studied in a multiple linear regression model wi th adjustment for age, sex, and body mass index. When sodium and potas sium were entered simultaneously into the multivariate model, a 100 mm ol increase in potassium was associated with a 9.4 decrease in systoli c (P=0.01) and a 4.9 mm Hg decrease in diastolic BP (P=0.01). Sodium w as directly related to BP, with a 2.2 mm Hg increase in systolic (P=0. 06) and a 0.8 mm Hg increase in diastolic BP (P=0.14) per 100 mmol. Ou r findings suggest that an increased intake of potassium and a decreas e intake of salt may lower BP at old age.