Is obesity associated with anemia of chronic disease? A population-based study.

Obesity is characterized by chronic, low-grade, systemic inflammation, which, in turn, has been associated with anemia of chronic disease. We hypothesized that obesity may be associated with the features of anemia of chronic disease, including low hemoglobin concentration, low serum iron and transferrin saturation (TS), and elevated serum ferritin. We compared normal-weight to overweight and obese adult participants of the third National Health and Nutrition Examination Survey with respect to hemoglobin concentration and levels of serum iron, TS, and ferritin. Measured BMI was used to categorize participants into normal weight (BMI < 25 kg/m(2), n = 6,059), overweight (BMI 25 to <30 kg/m(2), n = 5,108), mildly obese (BMI 30 to <35 kg/m(2), n = 2,366), moderately obese (BMI 35 to <40 kg/m(2), n = 850), and severely obese (BMI > or = 40 kg/m(2), n = 465). After adjustment for age, gender, menstruation, race/ethnicity, education, alcohol consumption, smoking, blood donation, and dietary iron intake, serum ferritin was progressively higher with increasing BMI category, whereas serum iron and TS were progressively lower. However, compared to normal-weight persons, those in all other higher BMI categories did not have a significant change in hemoglobin concentration after adjustment for the above-mentioned confounders. Overweight and obesity were associated with changes in serum iron, TS, and ferritin that would be expected to occur in the setting of chronic, systemic inflammation. However, overweight and obese persons were not more likely to be anemic compared with normal-weight persons.