APOB and metabolic syndrome: In summary, according to the NHANES 2007–2012, we found a cross-sectional association between low UIC measured by a spot urine sample and serum lipid profiles, particularly among total cholesterol, LDL cholesterol, and apolipoprotein B. Thus, efforts for maintaining adequate level of urinary iodine are recommended to prevent risk factors for dyslipidemia among US adults.