“…Minute amounts of ferritin also circulate in the plasma, and the concentration of serum ferritin correlates with total body iron stores. Serum ferritin is used to estimate total body iron stores in several mammalian species, including humans [Lipschitz et al, 1974], horses [Smith et al, 1984b], cattle [Furugouri et al, 1982], pigs [Smith et al, 1984a], dogs [Weeks et al, 1989], and cats [Andrews et al, 1994]. The relationship between serum ferritin and body iron stores in humans may not be as strong as previously thought; however, of the commonly measured iron analytes (e.g., serum ferritin, serum iron, unsaturated iron-binding capacity, and transferrin saturation), serum ferritin is still the best predictor of body iron stores [Beutler et al, 2002].…”