F001: Is systolic blood pressure related to potassium excretion?

Abstract

We had previously found in untreated hypertensive patients that 24 hour urinary sodium excretion correlated with diastolic pressure (r = 0.52, p = 0.0003, n = 50) and ambulatory diastolic pressure (r = 0.53, p = 0.01, n = 22), but not systolic pressure (r = −0.04). Systolic pressure increased with age (0.6 ± 0.2 mmHg/year, p = 0.001) and surprisingly correlated with potassium excretion. We therefore sought to confirm this prospectively. 46 consecutive newly-diagnosed untreated hypertensive patients (30 men, 16 women; age 43 ± 11 yrs) were studied. Blood pressure was measured on 3 occasions. Urine was collected for 24 hours for the measurement of electrolytes. We found that 24 hour urinary potassium excretion correlated with systolic blood pressure (r = −0.53, p < 0.001) (fig.). The correlation remains highly significant even after adjusting for age, gender, body mass index, ethanol intake and season (r = −0.50, p < 0.05). In a multiple regression analysis with systolic pressure as the dependent variable, the regression coefficient was −7.6 ± 1.7 mmHg/10 mmolK. Although systolic pressure increases with age, this was found only in subjects with below median potassium excretion (< 45 mmol/day) (r = 0.56, p < 0.01). In patients whose potassium excretion were above median, there was no relationship between systolic pressure and age. In conclusion, whereas diastolic blood pressure is strongly related to urinary sodium excretion in our hypertensive patients, systolic blood pressure is strongly related to potassium excretion, accounting for 28% of the variance. Our findings raise the possibility that a diet rich in potassium, such as through eating more fruits and vegetables, may prevent the seemingly inevitable rise in systolic pressure with age.

Potassium, systolic blood pressure