The relation between dietary sodium intake and hypertension is not a new concept and many epidemiological studies and laboratory findings have demonstrated it, this study investigated blood pressure changes during this regimen. Patients whose mean blood pressure on sixth day of the high-sodium diet exceeded by 13 mmHg or more than that of day six of the low-sodium diet, were classified as "salt-sensitive "and others as "saltresistant" . We determined the lithium clearance to know whether or not there was a correlation between salt-sensitivity without sodium manipulation.
Measurements of lithium clearance in these patients confirmed that salt-sensitives had significantly lower lithium clearance (9.27±4.37) than salt-resistants (20.75±9.86) (P<0.05).
Since the lithium clearance is a method for assessing tubular sodium and water reabsorption, our results advocate this hypothesis that sodium sensitivity in the hypertensive is related to dysfunction of the proximal tubules, it is predicted that lithium clearance could be used as determinant of salt-sensitivity without sodium manipulation.