Many people routinely donate blood, but doing so significantly depletes their iron stores, which may take months to fully replenish—causing concern that donors may be living "on the edge of anemia," Brittany Trang writes for STAT.

How blood donation can impact iron levels

According to Trang, a question that has "plagued the field of blood donation for as long as there have been transfusions" is whether donating blood may actually harm people.

In general, the body's iron levels are self-conserved since iron from old red blood cells is used to make new red blood cells. Unless a person loses blood, whether through menstruation, injury, or donation, iron does not leave the body.

Although a person's body will replace donated blood volume within 24 hours, the same is not true for the volume of red blood cells, which could take months to replenish. For donors who are low in iron, the process of replacing the iron lost through donation may take over four months—even though donors are technically eligible to give blood every 56 days.

To make the cutoff level for donation, many regular blood donors will take iron supplements to build up their red blood cells just enough to meet the cutoff in time for their next donation.

These donors "live on the edge of anemia so that they can donate blood," said Eldad Hod, an associate professor of pathology and cell biology and the vice chair of laboratory medicine at Columbia University Irving Medical Center.

How giving blood affects donors

To determine how donors are affected by blood donation, Hod and a team of researchers conducted a study to follow frequent donors who were low in iron but not anemic.

In the study, participants donated blood, which was then screened for its transfusion quality and whether the donors were low in iron. In total, 79 participants who donated blood had low iron and  were blindly randomized into two groups.

In one group, participants received intravenous iron to correct their iron deficiency, and in the other group, participants received a saline placebo. Then, four to six months later, the participants were asked to donate blood again and complete quality of life surveys, as well as cognitive function assessments.

Overall, Hod and his team found that there were no significant differences in transfusion quality, cognitive performance, or quality of life between participants who had their iron replenished and those who had not.

"The answer doesn't fit our preconception, but is actually better for public health because it suggests that what we're doing is not harming our donors," said Steven Spitalnik, executive vice chairman for laboratory medicine at Columbia's department of pathology and cell biology and one of the study's authors.

Although the researchers found that transfusion quality improved after iron repletion for women under the age of 50, they said that it is unclear whether this difference is clinically meaningful, and more study is needed. Notably, women under 50 are the group most likely to be turned away for blood donation because of low iron since they tend to lose iron through menstruation.

The study researchers noted that future studies should examine whether teenagers, who need higher amounts of iron for development, are similarly affected by blood donation or if it is harmful to them because of their increased iron requirements.

In addition, health experts said that potential donors who are identified as iron deficient should not just be told to take iron supplements. Instead, workers at donation centers could take the opportunity to encourage them to find a potential underlying cause for their deficiency.

Overall, the study's findings suggest that blood donation does not harm donors and that additional requirements for iron levels do not need to be added to donor screenings to ensure safety.

"We do no harm for people who give blood," said Gary Brittenham, a professor of medicine at Columbia and another author on the study, "but we're doing a great benefit to the people who need it." (Trang, STAT, 9/20)