A cross-sectional study found a high prevalence of absolute and functional iron deficiency among U.S. adults, including those without traditional risk factors.
The study, published in JAMA Network Open, estimated that 14% of U.S. adults had absolute iron deficiency, defined as serum ferritin less than 30 ng/mL regardless of transferrin saturation; 15% had functional iron deficiency, characterized by serum ferritin greater than or equal to 30 ng/mL with transferrin saturation less than 20%.
The study found that women younger than 50 years had the highest prevalence of absolute iron deficiency, at 34%. Among men, the prevalence of absolute iron deficiency was highest in those older than 65 years. Functional iron deficiency was more common than absolute in all age and sex categories except women younger than 50 years.
In fully adjusted multinomial regression models, the relative risk (RR) of absolute iron deficiency versus iron-replete status was significantly higher among women than men younger than 50. Similar results were obtained for the risk of functional iron deficiency versus iron-replete status for women younger than 50 compared with men younger than 50 and women aged 50 or older compared with men younger than 50.
Iron supplement use ranged from 22% to 35% among women with iron deficiency and 12% to 18% among men with iron deficiency, depending on age.
Higher body mass index was associated with higher serum ferritin levels but lower transferrin saturation. Individuals with anemia, heart failure, chronic kidney disease, or current pregnancy were more likely to have absolute, but not functional, iron deficiency than those without such conditions. Among adults without anemia, heart failure, chronic kidney disease, or current pregnancy, the estimated prevalence of absolute iron deficiency was 11%, and functional iron deficiency was 15%.
Dietary iron intake, alcohol use, and food security were not associated with absolute or functional iron deficiency. Marginal food security, but not low or low food security, was significantly associated with lower dietary iron intake.
The research analyzed data from 8,021 participants in the National Health and Nutritional Examination Survey 2017-2020 cycle of noninstitutionalized, civilian women and men aged 18 years or older who had available serum ferritin, iron, and unsaturated iron binding capacity measurements. The prevalence of absolute and functional iron deficiency was estimated among all adults in the U.S. and separately among women and men according to age category (> 18 years to < 50 years, 50-65 years, and ≥ 65 years) using recommended sample weights and sampling design factors to provide estimates representative of the national, noninstitutionalized civilian population.
No relevant disclosures were reported.