Dennis Gastineau started giving blood regularly when he was in medical school in the 1970s. The $25 he received bought almost enough groceries for a week. Now, it just seems like the right thing to do.
 

It may also be bad for his health. Gastineau, who happens to be a hematologist, is among the 2.4 million donors who risk silent damage as a result of frequent giving. U.S. government research published last year found this group iron-deficient, which can lead to fatigue, compromised mental function and eventually anemia. Now, iron levels are being examined as part of an $87.2 million study the U.S. is funding on blood donation and transfusion safety.
 

In the U.S., 70 percent of the blood supply comes from repeat donors. Limiting their giving may hamper a system that already suffers shortages. The Mayo Clinic predicts a 10 percent drop in its supply from its restrictions on donors after finding that one-third had iron deficiency.
 

“We want to make sure we don’t have a group of people walking around being iron deficient,” said Manish Gandhi, the medical director of the Mayo Clinic’s blood donation center. “Blood donation in the U.S. is an altruistic thing. We need to focus on what we should be doing to protect these wonderful donors.”
 

Almost 10 million Americans annually give blood. Still, that’s only 5 percent of those eligible, according to a national survey conducted by the U.S. Department of Health and Human Services. The agency’s REDS-III study, under way since 2011, is examining donors’ iron levels as part of an effort to improve blood banking and transfusion practices. Boosting the number of donors may be key to a healthier blood banking system.
 

Whole blood, which is divided into four components to treat everything from hemophilia to ulcers and accident victims, can now be given every two months, under rules set by the Food and Drug Administration.
 

The question is whether that’s too often. The FDA, National Heart, Lung and Blood Institute and the AABB, a nonprofit that represents the transfusion medicine industry, are struggling to find a way to minimize iron loss in donors without reducing the total blood supply. Researchers are working on a test to identify donors susceptible to iron deficiency that can be done during blood drives.
 

The use of iron supplements is a possible solution, though they can carry troublesome side effects such as an upset stomach and constipation. And while the American Red Cross generally encourages its donors to eat healthy meals to restore iron levels after giving blood, the metal is hard to absorb from food.
 

“Right now no one knows what the right answer is,” Gandhi said in a telephone interview.

Hiking Fatigue
For Gastineau, now a 61-year-old doctor specializing in blood cancers and bone marrow transplants at the Mayo Clinic in Rochester, Minnesota, the issue is professional and personal, he said in an interview.
 

Several years ago, during a hike through the mountains of northern New Mexico, he became so fatigued that he struggled to complete a trail he previously did with ease, he said. The culprit was depleted iron levels in his blood.
 

He stopped giving blood for a few months before each trek and his cut back donations to once or twice a year. Now he also takes iron for a month after each donation.
 

“I found out the hard way it’s not a good idea to donate blood and then try to hike in the mountains the next weekend,” Gastineau said. “It’s the reverse of blood doping.”

The Mayo Clinic where Gastineau works changed its policy in June after it found one-third of its donors had depleted iron stores. Now they must wait at least three months before giving blood to reduce the risks that can lead to anemia, a condition in which iron levels fall dangerously low.
 

Blood drives already test for hemoglobin, the iron-carrying protein in red blood cells that ferries oxygen throughout the body. Hemoglobin levels, though, may be normal in the early stages of iron loss, when there are usually no symptoms, said Richard Benjamin, chief medical officer of the American Red Cross.
 

“The early symptoms are very subtle,” Benjamin said by telephone. “It’s difficult to ask donors if they’re feeling tired, listless, depressed. Those are symptoms of the modern age.”
 

The U.S.-funded study probing iron deficiency in blood donors was published in April 2012 in the medical journal Transfusion. It found 20 percent of women who started donating regularly had no iron reserves and 51 percent produced iron deficient red blood cells.
 

The risks were higher for those who were already regular donors, the study found, with 27 percent of women having absent iron stores and 62 percent producing iron deficient red blood cells. Eighteen percent of regular male donors had depleted iron stores and 47 percent produced iron deficient red blood cells.
 

The Red Cross, which provides 40 percent of the blood supply nationwide, changed its policies this winter. It now recommends men who donate three or more times a year and women of child-bearing age who give blood more than twice annually to consider iron supplements. It doesn’t provide them.
 

“We changed our stance on the whole iron issue,” Benjamin said. “Research is being done through the National Institutes of Health, but we can’t really wait. We have to react now.”