Serum transferrin saturation, stroke incidence, and mortality in women and men. The NHANES I Epidemiologic Followup Study. National Health and Nutrition Examination Survey.

Several studies have examined relatively large body iron stores and the risk of coronary heart disease with conflicting results. No reports of studies that associated body iron stores with stroke were found. To test the hypothesis that relatively high transferrin saturation is associated with increased stroke incidence and mortality in women and men, data from a follow-up study of a national cohort were examined. A total of 5,033 women and men aged 45-74 years from the First National Health and Nutrition Examination Survey Epidemiologic Followup Study who were free of stroke at baseline were followed an average of 12 years. Transferrin saturation (serum iron concentration divided by total iron binding capacity) was used as a measure of the amount of circulating iron available to tissues. In white women aged 45-74, after adjusting for age or for age and other risk variables, the authors observed a significant U-shaped association of transferrin saturation with risk of incident stroke (> 44% vs. 30-36%, relative risk = 1.96, 95% confidence interval 1.15-3.36; < 20% vs. 30-36%, relative risk = 1.80, 95% confidence interval 1.20-2.71). However, no significant associations were found in white men aged 45-74 after adjusting for other risk variables. Similar findings were observed for stroke mortality in whites, but no significant associations were seen in blacks. The significantly increased risk of stroke that was seen at both high and low levels of transferrin saturation in white women should be confirmed in other cohorts of women and men.