Home testing of urine chloride to estimate dietary sodium intake: evaluation of feasibility and accuracy.

To estimate the utility of quantab chloride titrators, a product of Ames Laboratories, in estimating urine and diet sodium, two study populations were examined. The first consisted of 56 normotensive individuals providing timed, overnight, urine collections and 24-hour food records as part of the baseline assessment for a hypertension prevention study. The second group consisted of 19 study employees, who were instructed to maintain a low sodium diet, and to self-assess diet sodium and urine chloride at home. Results showed that urine chloride measured by quantab was highly correlated with urine sodium. Neither urine chloride nor urine sodium correlated highly with the previous day's intake of dietary sodium as measured by food record. It is estimated that five overnight urine samples would be required to estimate food record sodium to within +/- 25 mEq in individuals with relatively stable diets. Home assessment of urine chloride is feasible. It seems likely that clinical procedures which combine self-monitoring of dietary sodium intake by food record and home measurement of urine chloride concentration would be an effective way of providing persons prescribed sodium restricted diets with continuous and convergent feedback about their success in dietary adherence.