Urinary Potassium Excretion Inversely Correlates with Diastolic Blood Pressure Variability in Healthy Normotensive Adults

Abstract

High blood pressure (BP) is a common risk factor for cardiovascular disease (CVD), the leading cause of death worldwide. Dietary intake is an important contributor to BP. Increased dietary sodium intake has been shown to increase BP, while evidence suggests dietary potassium decreases BP. BP variability (BPV) refers to spontaneous fluctuations in BP that if exaggerated, are considered a risk factor for CVD. Limited work in this area suggests a high sodium diet may relate to increased BPV while potassium may decrease BPV. The purpose of our study was to investigate whether dietary intake of sodium and potassium relates to BPV in healthy, normotensive subjects. We hypothesized that individuals with a higher sodium intake, as well as increased sodium to potassium excretion ratio, would exhibit a higher BPV while those with increased potassium intake would have a lower BPV. Healthy men and women between the ages of 18 and 45 were recruited to participate. Habitual sodium and potassium intake was quantified with 24‐hour urine samples. During this same time period, subjects wore an ambulatory BP monitor for 24 hours with measures taken every 20 minutes during the day and every 30 minutes at night. These data were used to determine short term BPV. BPV was quantified by calculating the average real variability (ARV) index. Pearson bivariate correlations were run to assess the relation between sodium, potassium, and the sodium to potassium excretion ratio and the ARV of both systolic and diastolic BP. Additionally, partial correlations were run to control for the effects of age and sex. Fifty‐six (20M/36W) subjects (27±1 year; BMI 23±0.4; BP 114±1/67±1 mmHg) participated. Twenty‐four‐hour urinary potassium excretion was inversely associated with the ARV of diastolic BP (r=‐0.33, p=0.02). When controlling for age and sex this relation remained (r=‐0.31, p=0.03). However, neither 24‐hour urinary sodium excretion or the sodium to potassium excretion ratio was associated with the ARV of systolic (r=‐0.25, p=0.07; r=‐0.10, p=0.48, respectively) or diastolic BP (r=‐0.12, p=0.41; r=0.11, p=0.43, respectively). In summary, in this cohort of healthy normotensive adults, a higher potassium intake was associated with a lower diastolic BPV; however, there was no relation with sodium or the sodium to potassium excretion ratio. More research is needed to better understand the effects of both sodium and the ratio of sodium to potassium intake on BPV in healthy normotensive men and women.