Does Normal Reticulocyte Hemoglobin Rule out Iron Deficiency As a Cause of Normocytic Normochromic Anemia?

Background: Normochromic, normocytic anemia is the most frequently encountered type of anemia with a wide differential diagnosis. Iron studies are frequently ordered as part of the anemia work up as iron deficiency anemia could be potentially normocytic and normochromic. Recently reticulocyte hemoglobin has emerged as a marker to help identify early stages of iron deficiency at a time that other traditional biochemical studies for iron deficiency are non-informative. We hypothesize that normal reticulocyte hemoglobin level is a sensitive negative predictor of iron deficiency.

Aim:To evaluate whether a normal reticulocyte hemoglobin level can be used to exclude iron deficiency anemia in patients with normocytic normochromic anemia.

Methods:We reviewed the results of all hematological tests obtained as a part of hematopathology consults which were requested between January to April of 2016. Electronic medical records were screened for inclusion criteria. We included patient with hemoglobin less than 12g/dl, normal MCV (80-100) and normal reticulocyte hemoglobin level (>31 pg). We calculated the percentage of patients who had normal iron store suggested by ferritin, total iron binding capacity and iron saturation studies.

Results:We included 41 patients who has normocytic normochromic anemia with normal reticulocyte hemoglobin level. 39 out of 41 patients have normal iron studies indicating iron deficiency anemia was not the cause of anemia. The overall negative predictive value is 95.1%. Among the two patients whose ferritin levels are mildly decreased, suggesting possible iron deficiency, one patient had a blood transfusion prior to checking reticulocyte hemoglobin level. The other patient donates blood frequently and was started on oral iron supplementation trial without any hemoglobin improvement after two weeks. It appeared that these two patients might not have true iron deficiency.

Conclusion: Measurement reticulocyte hemoglobin level can serve as a useful marker to rule out iron deficiency as a cause of normocytic normochromic anemia. Serum Iron and ferritin studies are not indicated in patients with normocytic normochromic anemia with normal reticulocyte hemoglobin.