Relation of serum ferritin level to cardiovascular fitness among young men.

Although iron overload is associated with fatigue and low ferritin is associated with decreased cardiovascular fitness (CVF), little research has focused on the relation of elevated ferritin with CVF in young adult men. An analysis of the National Health and Nutrition Examination Survey 1999-2002 was conducted to examine the relation between elevated ferritin and CVF in relatively healthy young adult men. Adult men aged 20 to 49 years (unweighted n = 1,030, weighted n = 28,514,823) who participated in a treadmill test for CVF were evaluated. Logistic regressions were computed for ferritin with CVF, adjusting for age, race or ethnicity, body mass index, anemia, smoking, exercise, blood donation, and C-reactive protein. Subjects with ferritin >300 ng/ml were less likely than those with normal ferritin to have high CVF (odds ratio [OR] 0.57, 95% confidence interval [CI] 0.32 to 0.99). When ferritin was split into categories, in a fully adjusted model with a reference group of ferritin at 16 to 100 ng/ml, except for ferritin >100 but <150 ng/ml (OR 0.84, 95% CI 0.65 to 1.08), higher ferritin was associated with a decreased likelihood of high CVF (>150 but <200 ng/ml: OR 0.55, 95% CI 0.40 to 0.77; >200 but <300 ng/ml: OR 0.49, 95% CI 0.33 to 0.72; >300 ng/ml: OR 0.40, 95% CI 0.23 to 0.70). The prevalence of ferritin >150 ng/ml was 45.5% in young adult men. In conclusion, elevated ferritin levels, even those much lower than what is normally considered to be elevated, were associated with a decreased likelihood of having high CVF in young adult men.