Fast Colorimetric Method for Measuring Urinary Iodine (Technical Briefs‪)‬

International groups recommend the following median urinary iodine concentration as the best single indicator of iodine nutrition in populations: severe deficiency, 0-0.15 [micro]mol/L (0-19 [micro]g/L); moderate deficiency, 0.16-0.38 [micro]mol/L (20-49 [micro]g/L); mild deficiency, 0.40-0.78 [micro]mol/L (50-99 [micro]g/L); optimal iodine nutrition, 0.79-1.56 [micro]mol/L (100-199 [micro]g/L); more than adequate iodine intake, 1.57-2.36 [micro]mol/L (200-299 [micro]g/L); and excessive iodine intake, [greater than or equal to]2.37 [micro]mol/L ([greater than or equal to]300 [micro]g/L) (1). The range in which the median falls is more important than the precise number (2, 3). Many methods for assessing urinary iodine exist (3-8), most based on the Sandell-Kolthoff reaction (9), in which iodide catalyzes the reduction of ceric ammonium sulfate (yellow) to the colorless cerous form in the presence of arsenious acid. Although iodide is the chemical form for both the catalytic reaction and in urine, some preliminary treatment is needed to rid urine of impurities, most commonly by acid digestion (3, 5). We have extended previous approaches (5, 6, 10) with improved conditions and here present a new method ("Fast B") that is rapid, inexpensive, reliable, and flexible.