The relationship between cations and blood pressure in the People's Republic of China.

Blood pressure was measured in the north and in the south of the People's Republic of China in 1002 men and 1006 women. The 24-hour urinary excretion of sodium, potassium, calcium, magnesium, and creatinine was measured, and the relationship between urinary cations and blood pressure was studied. Blood pressure and 24-hour sodium excretion were higher in northern China than in southern China. With some exceptions, a positive correlation was found between urinary sodium and blood pressure and a negative one between 24-hour urinary potassium excretion and blood pressure. Urinary calcium correlated negatively and urinary magnesium did not correlate significantly with blood pressure. The sodium/potassium ratio correlated positively with blood pressure, and the calcium/magnesium ratio, negatively. This study confirms the positive within-population relationship between sodium intake and blood pressure in Oriental populations.