International groups recommend the following median urinary iodine concentration as the best single indicator of iodine nutrition in populations: severe deficiency, 0–0.15 μmol/L (0–19 μg/L); moderate deficiency, 0.16–0.38 μmol/L (20–49 μg/L); mild deficiency, 0.40–0.78 μmol/L (50–99 μg/L); optimal iodine nutrition, 0.79–1.56 μmol/L (100–199 μg/L); more than adequate iodine intake, 1.57–2.36 μmol/L (200–299 μg/L); and excessive iodine intake, ≥2.37 μmol/L (≥300 μg/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)(4)(5)(6)(7)(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. The equipment required for the Fast B method includes a heating block, Pyrex test tubes (13 × 100 mm), two fixed-volume pipettes (0.5 mL and 1.0 mL), one adjustable pipette (0–200 μL), and a multipet (Eppendorf) for quick reagent volume additions of 0.125 and 0.1 mL. The basic chemicals used are potassium iodate, arsenic trioxide, ammonium persulfate, ammonium cerium(IV) sulfate dihydrate, sodium chloride, ferroine, and sulfuric acid. The solutions used in the assay are as follows: