Rapid urinary iodide test

Assessment of iodine deficiency and monitoring of iodine supplementation pr ograms demands rapid simple and cost-effective methods for the determinatio n of urinary iodide concentrations. We propose a rapid test based on the io dide-catalyzed oxidation of 3,3 ',5,5'-tetramethylbenzidine by peracetic ac id/H2O2 to yield colored products. The color of the chemical reaction is co mpared with color categories of a pictogram corresponding to three ranges ( <10, 10-30, and much greater than 30 mu g/100 mL) of iodide concentrations. The test is very easy to perform and does not require any instrumentation or apparatus. Sample preparation is simple and consists in the removal of i nterfering substances by disposable columns, 65 x 10.5 mm, packed with spec ifically prepared activated charcoal. For comparison with a reference metho d for measuring urinary iodide (HPLC), we determined the iodide concentrati ons of 370 random (untimed) urine samples from consecutive patients by both HPLC and the rapid test. The results obtained by both methods are in close agreement with respect to classification of the samples according to the above three ranges, with a maximum difference of <5% for each range. This rapid test is therefore very well suited to epidemiological surveys of iodine deficiency especially in developing countries.