Urinary sodium or potassium excretion and blood pressure in adults of Shandong province, China: preliminary results of the SMASH project

The aim of the study was to estimate the urinary electrolyte excretion and assess the relationship between dietary sodium or potassium intake and blood pressure within a population of 18-69 adults in Shandong province, China. Random samples of 2184 adults enrolled in the Shandong and Ministry of Health Action on Salt reduction and Hypertension project were collected from 20 countries or districts. Electrolyte intake was estimated by 24-hour urine collections, and urinary volume or creatinine was measured to estimate the accuracy of the collection. Anthropometry was measured with standard procedures. Regression analysis was used to assess the relationship between electrolyte excretion and blood pressure. The mean sodium excretion was 241.8 ± 7.9 mmol among men and 222.3 ± 7.9 mmol among women, respectively. The 24-hour average potassium excretion was 39.9 ± 0.9 and 41.8 ± 1.1 mmol, respectively. Some resident and geographic differences were found for 24-hour urinary electrolyte. Regression analysis showed increments of 1.15 mm Hg in systolic blood pressure and 0.67 mm Hg in diastolic blood pressure per gram increment in urinary sodium excretion. For each increment of 1-g potassium excretion per day, there was a decrement of 0.81 mm Hg in systolic blood pressure and 0.76 mm Hg in diastolic blood pressure. The highest blood pressure was observed in the group with lowest potassium and the highest sodium excretion, which was 13.6 mm Hg in systolic blood pressure and 7.3 mm Hg in diastolic blood pressure difference from group with highest potassium excretion and lowest sodium excretion (P < .0001 for interaction). The Shandong and Ministry of Health Action on Salt reduction and Hypertension project results show a substantially higher sodium excretion and a lower potassium excretion than recommended in Shandong adults. The sodium or potassium intake is positively association with blood pressure. These results support the recommended approaches to lower the risk of hypertension, including lower sodium intake, higher potassium intake, and prevention and control of obesity.