Urine Chloride/Creatinine Ratio for Estimation of Urine Sodium

We plan to assess the accuracy of a new means of estimating urine sodium excretion. We will compare the chloride to creatinine ratio obtained by titrator sticks with urine sodium measured by a standard laboratory. If found to approximate sodium excretion, the titrator sticks could provide a convenient means for doctors and patients to monitor their salt intake.

Level of salt intake has an important impact in patients with high blood pressure or congestive heart failure. Despite this there is no convenient way for doctors or patients to assess their salt intake other than diet recall, which is unreliable, or measurement of sodium excretion in a 24 hour collection of urine, which is very inconvenient. As a result, salt intake is not monitored in most patients. 2 innovations might enable a more convenient assessment of salt intake. A titrator stick that measures chloride ion concentration (chloride and sodium concentrations correlate strongly with each other), and a titrator stick that measures urine creatinine. The latter enables estimation of 24 hour excretion from a single sample of urine. In assessing sodium intake, a measurement that provides an approximation of urine sodium intake would be of considerable clinical value In this study, we shall compare the estimation of urine sodium excretion measured by a laboratory with estimation of sodium excretion from measurement of chloride/creatinine ration in a random urine sample. We will compare the estimate obtained by titrator stick with the sodium concentration from the same urine sample, and from measurements obtained from a 24 hour urine collection. In the next phase we will also compare the average estimate from titrator stick obtained on 3 different days with the measurement obtained from 3 24 hour urine collections. We will assess the accuracy with which the titrator stick estimate approximates the measured urine sodium. As of March 2007, we have recruited 50 subjects, and continue to study the predictive value of spot urine chloride/creatinine ratio, as described.