Urinary electrolytes and blood pressure in three Yi farmer populations, China

The relation between blood pressure and urinary electrolytes, including sodium, potassium, calcium, and magnesium were examined in male farmers of the Yi nationality who live in three separate communities in Sichuan and Yunnan provinces in China, where the lifestyles, habits, and living conditions are very different. One of these three communities was unacculturated and had the lowest average blood pressure as well as the lowest prevalence rate of hypertension in China; one was acculturated and had the highest average blood pressure; and the third was moderately acculturated with its average blood pressure between the other two. Blood pressure was taken on each of 3 days and corresponding 24-hour urine specimens were collected to measure potassium, sodium, calcium, magnesium, urea nitrogen, and creatinine. Ecological and individual-based data correlation analyses were employed to study the relations among age, body mass index, some related indexes of electrolyte derivatives, and blood pressure. Multiple regression analyses were used to explore the relation of blood pressure to the above indexes, adjusted for age, body mass index, urea nitrogen and creatinine, and geographical differences. Statistically significant correlation analyses showed that systolic blood pressure was positively associated with sodium-creatinine, calcium-creatinine, sodium-potassium, calcium-magnesium, and urea nitrogen and creatinine ratios; negatively associated with potassium-creatinine and magnesium-creatinine ratios. The ridge regression analysis selected only calcium-magnesium ratio as a predictor of systolic blood pressure.