to the editor: After reading the excellent review of iron deficiency anemia by Dr. Killip and colleagues last year, my threshold for testing for this condition decreased substantially. However, in the following year, I was surprised that I made the diagnosis of iron deficiency without anemia nearly as often as iron deficiency anemia. The most common type of patient for whom I made this diagnosis was a middle-aged frequent blood donor complaining of fatigue, angular cheilitis, or restless legs. Often, patients would express surprise at the diagnosis, recalling that the blood bank had informed them hat their “iron level” was normal.

Much of the available research on iron deficiency is grouped with iron deficiency anemia. However, there is evidence of morbidity associated with iron deficiency in non-anemic patients. Iron supplementation has been shown to improve fatigue in non-anemic women with iron deficiency.¹ The duration of exercise achieved before muscle fatigue has been shown to improve with iron therapy in non-anemic iron-deficient women.² In a study measuring verbal learning and memory in iron-deficient adolescent girls without anemia, both of these parameters improved with iron supplementation.³ Additionally, treating low iron levels has been shown to reduce symptoms of restless legs syndrome.⁴

The American Red Cross Blood Donation Eligibility Guidelines require a hemoglobin level of at least 12.5 g per dL (125 g per L) for blood donation.⁵ However, iron deficiency is not listed as an exclusion criterion. The American Red Cross does not require testing for adequate iron stores even for long-term frequent blood donors. Perhaps guidelines should be established to determine which blood donors would benefit from screening for iron deficiency in the absence of anemia.