Iron stores and hemoglobin are negatively related with carotid atherosclerosis: the Tromsø Study. A cross-sectional study

Abstract

Background: Cardiovascular diseases (CVD) remain the leading cause of mortality and morbidity globally. Iron has been suggested to have role in CVD though, epidemiological findings have been conflicting. The primary aim of this study was to investigate the possible role of body iron in carotid atherosclerosis in a population-based survey. Further, we wanted to analyze the prevalence of carotid plaques and differences in gender and age. Material and methods: We performed a cross-sectional study based on data from the fifth survey of the Tromsø Study conducted in 2001-2002. Atherosclerosis was measured by ultrasound examination of the carotid artery in a total of 5423 subjects aged between 32 to 89 years. Iron status was obtained through laboratory measurements of hemoglobin, s-ferritin, s-transferrin, transferrin saturation, s-iron and s-TIBC. Results: Iron stores and hemoglobin were negatively associated with carotid plaque. The third and the fourth quartiles of s-ferritin showed reduced odds by 54.6 % (OR=0.454, 95% CI=0.272 to 0.758) and by 52.9% (OR=0.471, 95% CI=0.286 to 0.774) respectively, compared with the lowest ferritin quartile towards high plaque load in women. Likewise, hemoglobin had a protective effect in plaque presence and in high plaque load in women, being reduced by 11.3% odds (OR=0.887, 95% CI=0.802 to 0.980) and by 18.3% odds (OR=0.817, 95% CI=0.674 to 0.989) respectively, per 1 unit increase in hemoglobin compared to men. Conclusion: High levels of iron seem to be protective of plaque presence, high plaque load and plaque area with consistent findings in women, suggesting that they were associated with lower risk of disease.