Objective: This study examines the association between serum ferritin levels and cardiovascular risk factors.
Design: The data were obtained from a cross-sectional survey designed to assess the nutrition situation, with special reference to cardiovascular risk factors.
Subjects and setting: The study population was 337 healthy men, median age 38 years (range 21-59), working at oil platforms in the North Sea.
Results: The associations between serum ferritin, risk factor levels and anthropometric measurements were analysed by age-adjusted partial correlations, step-wise multiple regression, and one-way ANOVA analysis. Body mass index and waist-to-thigh ratio were the strongest predictors for serum ferritin when controlling for age (P < 0.001). In multiple regression analysis, when anthropometric measurements were excluded, fibrinogen, high density lipoprotein (HDL)-cholesterol and diastolic blood pressure were significant predictors for serum ferritin levels when controlling for age (P < 0.001). There was a significant difference in triglyceride concentration between those with low stores of iron and those with high stores (P = 0.006). There were consistently higher levels of total cholesterol, triglycerides, fibrinogen, diastolic and systolic blood pressure, except for HDL where it was reversed, in the highest quartile of serum ferritin levels compared to the lowest. For all the variables the differences between the quartiles of serum ferritin were significant.
Conclusion: These findings support the hypothesis that the associations between cardiovascular arteriosclerotic disease and serum ferritin are at least partially caused by confounding.
Sponsorship: The project was supported by the Norwegian State Oil Company (STATOIL), Amoco Norway Oil Company and Ross Offshore AS.