Bulletin of the World Health Organization
Print version ISSN 0042-9686
DELANGE, François; BENOIST, Bruno de; BURGI, Hans and ICCIDD WORKING GROUP. Determining median urinary iodine concentration that indicates adequate iodine intake at population level. Bull World Health Organ [online]. 2002, vol.80, n.8, pp. 633-636. ISSN 0042-9686. http://dx.doi.org/10.1590/S0042-96862002000800007.
OBJECTIVE: Urinary iodine concentration is the prime indicator of nutritional iodine status and is used to evaluate population-based iodine supplementation. In 1994, WHO, UNICEF and ICCIDD recommended median urinary iodine concentrations for populations of 100- 200 µg/l, assuming the 100 µg/l threshold would limit concentrations <50 µg/l to £20% of people. Some scientists felt this proportion was unacceptably high and wanted to increase the threshold above 100 µg/l. The study was carried out to determine the frequency distribution of urinary iodine in iodine-replete populations (schoolchildren and adults) and the proportion of concentrations <50 µg/l. METHOD: A questionnaire on frequency distribution of urinary iodine in iodine-replete populations was circulated to 29 scientific groups. FINDINGS: Nineteen groups reported data from 48 populations with median urinary iodine concentrations >100 µg/l. The total population was 55 892, including 35 661 (64%) schoolchildren. Median urinary iodine concentrations were 111-540 (median 201) µg/l for all populations, 100-199 µg/l in 23 (48%) populations and ³200 µg/l in 25 (52%). The frequencies of values <50 µg/l were 0-20.8 (mean 4.8%) overall and 7.2% and 2.5% in populations with medians of 100-199 µg/l and >200 µg/l, respectively. The frequency reached 20% only in two places where iodine had been supplemented for <2 years. CONCLUSION: The frequency of urinary iodine concentrations <50 µg/l in populations with median urinary iodine concentrations ³100 µg/l has been overestimated. The threshold of 100 µg/l does not need to be increased. In populations, median urinary iodine concentrations of 100-200 µg/l indicate adequate iodine intake and optimal iodine nutrition.
Keywords : Iodine [urine]; Iodine [deficiency]; Urine [chemistry]; Nutritional status; Reference values; Epidemiologic studies; Child; Adult.