Iodine status has been historically assessed by palpation of the thyroid and reported as
goiter rates.
Goiter is a functional
biomarker that can be applied to both individuals and populations, but it is subjective.
Iodine status is now assessed using an objective
biomarker of exposure, i.e., urinary
iodine concentrations (UICs) in spot samples and comparison of the median UIC to UIC cut-offs to categorize population status. This has improved standardization, but inappropriate use of the crude proportion of UICs below the cut-off level of 100 µg/L to estimate the number of
iodine-deficient children has led to an overestimation of the prevalence of
iodine deficiency. In this review, a new approach is proposed in which UIC data are extrapolated to
iodine intakes, adjusted for intraindividual variation, and then interpreted using the estimated average requirement cut-point model. This may allow national programs to define the prevalence of
iodine deficiency in the population and to quantify the necessary increase in
iodine intakes to ensure sufficiency. In addition,
thyroglobulin can be measured on dried blood spots to provide an additional sensitive functional
biomarker of
iodine status.