Is low iodine a risk factor for cardiovascular disease in Americans without thyroid dysfunction? Findings from NHANES

Area of Science:

• Endocrinology
• Cardiovascular Medicine
• Nutritional Science

Background:

• Low body iodine levels are linked to cardiovascular disease, potentially via thyroid function alterations.
• Animal studies suggest this association, but human evidence is limited.
• This study investigates iodine levels and cardiovascular disease in adults without thyroid dysfunction.

Purpose of the Study:

• To examine the association between urine iodine levels and the presence of coronary artery disease (CAD) and stroke.
• To assess this relationship in a large, nationally-representative sample of adults without diagnosed thyroid dysfunction.

Main Methods:

• Cross-sectional analysis of 2440 adults (weighted n=91,713,183) from the 2007-2012 National Health and Nutrition Examination Survey.
• Urine iodine/creatinine ratio (aICR) categorized into low, medium, and high levels.
• Multivariable logistic regression used to model the association between low urine aICR and CAD or stroke.

Main Results:

• Low urine iodine levels were significantly associated with a higher odds of CAD (aOR=1.97, 1.08-3.59) compared to high iodine levels.
• No significant association was found between low or medium urine iodine levels and stroke.
• The study population (aged ≥40) was primarily non-Hispanic white (75%) with a mean age of 56.0 years.

Conclusions:

• A significant association exists between low urine iodine levels and coronary artery disease.
• Prospective studies with serial iodine measurements are recommended to confirm these findings.
• Low iodine may represent a modifiable risk factor for CAD, warranting further investigation for therapeutic implications.