Relationships Between Blood Pressure and 24-Hour Urinary Excretion of Sodium and Potassium by Body Mass Index Status in Chinese Adults

Abstract

This study examined the impact of overweight/obesity on sodium, potassium, and blood pressure associations using the Shandong-Ministry of Health Action on Salt Reduction and Hypertension (SMASH) project baseline survey data. Twenty-four-hour urine samples were collected in 1948 Chinese adults aged 18 to 69 years. The observed associations of sodium, potassium, sodium-potassium ratio, and systolic blood pressure (SBP) were stronger in the overweight/obese population than among those of normal weight. Among overweight/obese respondents, each additional standard deviation (SD) higher of urinary sodium excretion (SD=85 mmol) and potassium excretion (SD=19 mmol) was associated with a 1.31 mm Hg (95% confidence interval, 0.37-2.26) and -1.43 mm Hg (95% confidence interval, -2.23 to -0.63) difference in SBP, and each higher unit in sodium-potassium ratio was associated with a 0.54 mm Hg (95% confidence interval, 0.34-0.75) increase in SBP. The association between sodium, potassium, sodium-potassium ratio, and prevalence of hypertension among overweight/obese patients was similar to that of SBP. Our study indicated that the relationships between BP and both urinary sodium and potassium might be modified by BMI status in Chinese adults.

Figure 1

Systolic blood pressure values by body mass index (BMI) status and 24‐hour sodium excretion, 24‐hour potassium excretion, and sodium‐potassium ratio. Data source: Shandong and Ministry of Health Action on Salt and Hypertension (SMASH) project 2011 survey, among adults (N=1948) in Shandong Province, China. According to the Chinese guidelines for overweight and obesity, overweight is defined as a BMI of 24 to <28. Those with a BMI ≥28 are considered obese. Footnote: We updated Figure footnote as ‘We used 10th, 30th, 50th, 70th, and 90th percentiles as the mid‐value of each quintile for sodium and potassium excretion and sodium‐potassium ratio. The value for P10, P30, P50, P70, and P90 for sodium was 137.0, 188.9, 230.3, 255.4, and 341.3 mmol for the entire population, 129.9, 178.6, 217.9, 249.5, and 312.5 mmol among the normal‐weight population, and 144.4, 201.3, 239.8, 257.9, and 365.4 mmol among the overweight/obese population. The value for P10, P30, P50, P70, and P90 for potassium was 19.7, 29.2, 37.7, 47.6, and 65.0 mmol for the entire population, 19.2, 28.3, 36.5, 45.5, and 61.9 mmol among the normal‐weight population, and 20.1, 30.3, 39.0, 49.2, and 68.0 mmol among the overweight/obese population. The value for P10, P30, P50, P70, and P90 for sodium‐potassium ratio was 3.4, 4.7, 5.8, 7.7, and 11.0 for the entire population, 3.3, 4.6, 5.7, 6.4, and 10.9 among the normal‐weight population, and 3.5, 4.7, 5.9, 7.8, and 11.2 among the overweight/obese population.’