Understanding iron depletion and overload in blood donors

Abstract

Normal iron stores in healthy men are about 1000 mg, whereas in healthy females only about 300 mg. A whole‐blood donation depletes the donor of approximately 225–250 mg of iron. For females, this means that often her iron stores are completely depleted after only one donation. Dietary absorption of iron can be up to 3·5–4 mg/day when iron stores are low, less when iron stores are higher. It can take 5 months or more for haemoglobin (Hb) to return to 80% of the drop in Hb following a whole‐blood donation, and longer to recoup iron stores; hence, to donate frequently, many donors may require iron supplements. Low iron stores are usually related to diet and blood donation, but can also be a sign of underlying pathology. Hb is routinely measured to determine donor eligibility. However, because iron stores will be largely depleted before Hb concentrations drop, it is a late‐stage indicator of iron deficiency. Serum ferritin is correlated with total body iron, thus is a convenient marker of iron status. Recent studies have shown that iron depletion is common among blood donors. Some people, especially young females, have low iron stores on their first donation. However, low iron stores are correlated with higher frequency of blood donation in both females and males. In countries largely reliant on regular donors, a high proportion of donors may be iron deficient. Low iron stores are sometimes associated with fatigue, pica and restless leg syndrome. There may be other health consequences, but large prospective blood donor studies are required. To address low iron stores in blood donors, there are a range of potential strategies to choose from. These include providing donor education about iron, reducing donation frequency, providing iron supplements and/or testing donor ferritin levels and notifying them of abnormal results. The threshold Hb for male donors can be raised. Ideally, deferral for low Hb should be long enough to recoup body iron stores, and iron supplements have been shown to be beneficial. Hemochromatosis, a condition of excess iron stores, is usually a genetic disorder. If left untreated, iron overload is associated with end‐organ damage to the heart and liver. Treatment usually involves phlebotomy, thus donating blood can be beneficial. Donors who have iron overload may be unaware of their condition, and iron supplements could be detrimental. Many blood services are performing studies and revising policies to better address iron status and safety of blood donation. Due to country‐specific factors such as the nutritional/health status of the population, variable reliance on repeat donation and operational issues, no one policy will suit all centres.