Effect of blood donation on iron stores as evaluated by serum ferritin.

Serum ferritin was measured in 2982 blood donors. First-time male donors had a geometric mean of 127 microgram/liter and female donors 46 microgram/liter. While values were essentially constant in the women between the ages of 18 and 45, there was a rapid increase in the men between 18 and 30 years of age consistent with the establishment of iron stores during that time. Blood donation was associated with a decrease in serum ferritin. One unit per year, equivalent to an increased requirement of 0.65 mg/day, halved the serum ferritin level in the male. More frequent donations were associated with further decreases. From the data obtained it would appear that male donors, while depleting their iron stores, were able to donate 2-3 U/yr without an appreciable incidence of iron deficiency. Women could donate only about half that amount, and more frequent donations were associated with a high incidence of iron deficiency and donor dropout. These data have provided information on the effect of graded amounts of iron loss through bleeding on iron balance.