Survival without cardiac disease according to the proportion of serum ferritin measurements greater than 2,500 μg/dL. The circles show cardiac disease free survival among patients in whom less than 33% of serum ferritin measurements exceeded 2,500 μg/L; squares show survival among patients in whom 33% to 67% of ferritin measurements exceeded 2,500 μg/L; and triangles show survival among patients in whom more than 67% of ferritin measurements exceeded 2,500 μg/L. (Reprinted by permission of The New England Journal of Medicine, Olivieri NF, Nathan DG, MacMillan JH, et al. Volume 331, pp 574-578, 1994. Copyright 1994. Massachusetts Medical Society. All rights reserved.)91