90 % of ingested iodine is excreted via renal pathways, such that median spot urinary iodine concentrations (UIC) will serve as a biomarker for recent dietary iodine intake (1).
The most recent Food and Drug Administration's Total Diet Study also revealed that the U.S. population has adequate dietaryiodine, with estimated average daily iodine intake ranging from 138 to 353 micrograms per person (8).