Association study of urinary iodine concentrations and coronary artery disease among adults in the USA: National Health and Nutrition Examination Survey 2003-2018

Iodine is a vital trace element in the human body and is associated with several important coronary artery disease (CAD) risk factors. We aimed to explore the correlation between urinary iodine concentration (UIC) and CAD. Data from 15 793 US adults in the National Health and Nutrition Examination Survey (2003-2018) were analysed. Weconducted multivariable logistic regression models and fitted smoothing curves to study the correlation between UIC and CAD. Furthermore, we performed subgroup analysis to investigate possible effect modifiers between them. We found a J-shaped association between UIC and CAD, with an inflection point at Lg UIC = 2 center dot 65 mu g/l. This result indicated a neutral association (OR 0 center dot 89; 95 % CI 0 center dot 68, 1 center dot 16) between UIC and CAD as Lg UIC < 2 center dot 65 mu g/l, but the per natural Lg [UIC] increment was OR 2 center dot 29; 95 % CI 1 center dot 53, 3 center dot 43 as Lg UIC = 2 center dot 65 mu g/l. An interaction between diabetes and UIC might exist. The increase in UIC results in an increase in CAD prevalence (OR 1 center dot 84, 95 % CI 1 center dot 32, 2 center dot 58) in diabetes but results in little to no difference in non-diabetes (OR 0 center dot 98, 95 % CI 0 center dot 77, 1 center dot 25). The J-shaped correlation between UIC and CAD and the interaction between diabetes and UIC should be confirmed in a prospective study with a series of UIC measurements. If excessive iodine precedes CAD, then this new finding could guide clinical practice and prevent iodine deficiency from being overcorrected.