Blood donation and anemia

Is there a problem?

Voluntary blood donation is a common and necessary practice in Canada. Each year, 950 000 units of whole blood are collected in Canada outside Quebec^1,2 and most get used within the year for blood transfusions across the country.

Donating blood is an altruistic act for which most donors cannot expect any health benefit in return. Possible reductions in cardiac disease, noted in early retrospective analyses of blood donors, have not been demonstrated in subsequent larger prospective studies.³ In this volunteer setting, it is essential to recognize and reduce possible harms of blood donation without deterring potential or current donors, who are critical to the blood supply. Iron deficiency anemia (IDA) is one of these potential harms.

What is the extent of the problem?

Iron deficiency anemia is common, particularly in women, for whom pregnancy and menstruation are the dominant causes.⁴ The overall prevalence of anemia in the Canadian Health Measures Survey of 2009 to 2011 was 3% in women aged 20 to 49 years, with a 9% rate of iron deficiency (ID).⁵ Blood donation in this already vulnerable population can cause or contribute to ID and IDA, with recurrent donation increasing the risk.^1,6 In Canada, 8% to 10% of repeat donors are asked to defer donation owing to a hemoglobin level of less than 125 g/L,¹ which is 3 times the baseline rate of anemia in the population. The recent RISE (REDS-II Donor Iron Status Evaluation) study⁶ showed even more concerning results: among 2425 men and women in the United States accepted for blood donation, 66% of the frequent women donors and 49% of the frequent men donors were iron deficient. Many such patients will not see physicians and will continue to try to donate every 56 days (the minimum recovery period suggested by Canadian Blood Services). Even for those who do see physicians, if they do not ask about blood donation, physicians might overlook this important cause of ID and IDA, and might also initiate inappropriate investigations looking for other underlying causes.

Iron deficiency alone, without IDA, can contribute to symptoms. Low ferritin levels have been associated with fatigue, exercise intolerance, restless legs, reduced cognitive function, and pica, particularly for ice (pagophagia).^7,8 Iron replacement in these patients has been shown to reduce symptoms in many studies.^3,9–12

Canadian Blood Services has begun to study ferritin levels in blood donors, in addition to the current point-of-care hemoglobin testing, to determine the extent of ID in donors and update recommendations accordingly.¹

What can family physicians do?

Conclusion

Iron deficiency anemia is common in blood donors, especially in female donors of childbearing age. By prevalence, blood donation is equivalent to gastric ulcers or carcinoma as a cause of IDA.⁴ Family physicians can reduce harm by asking about blood donation, considering iron supplementation, and reducing donation frequency in patients with signs or symptoms of ID or IDA. They can also consider deferring other investigations for IDA in frequent blood donors unless symptoms strongly suggest alternative causes or if patients’ symptoms do not respond to iron therapy. By taking these steps, physicians protect Canada’s future blood supply; even if people donate less often, keeping them healthy improves the chances that they will continue to donate for life.