Don't sweat the small stuff: skin mechanisms of sodium homeostasis and associations with long-term blood pressure.

Despite the overwhelming evidence that the kidney is the principal regulator of chronic blood pressure though the ability to sense pressure and adjust blood volume accordingly, recent clinical and preclinical evidence suggests that skin clearance of Na+ through sweat significantly contributes to long-term blood pressure and risk of hypertension. Evidence indicates that changes in skin Na+ content negatively associate with renal function, and factors that influence the concentration of Na+ in sweat are affected by major regulators of Na+ excretion by the kidney such as angiotensin and aldosterone. In addition, known regulatory mechanisms that regulate the amount of sweat produced do not include changes in Na+ intake or blood volume. Because of these reasons, it will be hard to quantify the contribution of Na+ clearance through sweat to blood pressure regulation and hypertension. While Chen et al. demonstrate significant negative associations between sweat Na+ concentration and blood pressure, it is likely that Na+ clearance through the skin has a short-term influence on blood pressure and sweat Na+ concentration is most likely a biomarker of renal function and its key role in hypertension.