ABSTRACT
A convenient way to determine salt intake is salt excretion using spot urine (e-NaCl). We measured e-NaCl at health checkups and compared results with seasonal changes in blood pressure. Among 19,732 examinees who underwent health checkups from Aug. 2012 to Mar. 2013, age, body weight and e-NaCl were measured and compared to monthly mean systolic blood pressure (SBP). Excluded were those taking antihypertensive drugs and with creatinine levels higher than 2.0 mg/dL. Also examined was salt intake (i-NaCl) by an interview survey from Aug. to Dec. 2012. Correlations with SBP were R = 0.7718 for age, R = 0.5996 for body weight, R = 0.2498 for i-NaCl and R = 0.9335 for e-NaCl. e-NaCl decreased in summer. It was presumed that the reduced burden on the kidney of salt excretion due to sweating may be related to decreases in blood pressure in summer.
