Positive relationship between urinary sodium chloride and blood pressure in chinese health examinees and its association with calcium excretion

The relationships between salt, urinary calcium and blood pressure were studied in 401 middle-aged Chinese men. Seven overnight urine samples were collected. Three consecutive blood pressure measurements were made on two occasions. The 24-h urinary sodium estimate was positively associated with both mean systolic and diastolic blood pressure (P < 0.001), controlled for age and body mass index. Urinary chloride was also positively associated with blood pressure (P < 0.001) at a magnitude similar to that of sodium. Potassium was not related to blood pressure. Urinary calcium was significantly correlated to sodium (r = 0.46) and was positively associated with systolic (P < 0.001) and diastolic (P < 0.01) blood pressure. The relationship between calcium and blood pressure was partly explained by salt intake. Similar findings were obtained using electrolyte to creatinine ratios. These results confirm the positive relationship between salt and blood pressure within a Chinese population living in Taipei and indicate a possible, positive relationship between blood pressure and urinary calcium excretion, either dependent or independent of salt intake.