Iodine status of Indigenous and non-Indigenous young adults in the Top End, before and after mandatory fortification.

Objective: To assess the median urine iodine concentration (UIC) of young adults in the Top End of Northern Territory, before and after fortification of bread with iodised salt became mandatory.

Design, Setting: Analysis of cross-sectional data from two longitudinal studies, the Aboriginal Birth Cohort and the non-Indigenous Top End Cohort, pre- (Indigenous participants: 2006-2007; non-Indigenous participants: 2007-2009) and post-fortification (2013-15).

Participants: Indigenous and non-Indigenous Australian young adults (mean age: pre-fortification, 17.