Iodine Nutrition in the United States. Trends and Public Health Implications: Iodine Excretion Data from National Health and Nutrition Examination Surveys I and III (1971–1974 and 1988–1994)

Iodine deficiency in a population causes increased prevalence of goiter and, more importantly, may increase the risk for intellectual deficiency in that population. The National Health and Nutrition Examination Surveys [NHANES I (1971–1974) and (NHANES III (1988–1994)] measured urinary iodine (UI) concentrations. UI concentrations are an indicator of the adequacy of iodine intake for a population. The median UI concentrations in iodine-sufficient populations should be greater than 10 μg/dL, and no more than 20% of the population should have UI concentrations less than 5 μg/dL. Median UI concentrations from both NHANES I and NHANES III indicate adequate iodine intake for the overall U.S. population, but the median concentration decreased more than 50% between 1971–1974 (32.0 ± 0.6 μg/dL) and 1988–1994 (14.5 ± 0.3 μg/dL). Low UI concentrations (