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INTRODUCTION

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SUMMARY

The anemia that results from deficiencies of vitamin B12, folic acid (Chap. 41) or iron (Chap. 43) are, in general, clearly defined and are relatively common. In contrast, characteristics of anemia that may occur with deficiencies of the other vitamins and minerals are poorly defined and relatively rare in humans. When present, they usually exist not as isolated deficiencies of one vitamin or one mineral, but rather, as a combination of deficiencies resulting from malnutrition or malabsorption. In this context, it is difficult to deduce which abnormalities are the result of which deficiency. Studies in experimental animals may not accurately reflect the role of micronutrients in humans. Accordingly, our knowledge of the effects of many micronutrients on hematopoiesis is fragmentary and based on clinical observations and interpretations that may be flawed. Inborn metabolic errors that affect single micronutrient pathways may shed light on specific effects of those micronutrients on hematopoiesis. Daily requirements of some micronutrients are available at: http://www.nal.usda.gov/fnic/dga/rda.pdf, and levels normally found in serum, red cells, and leukocytes are shown in Table 44–1.

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Acronyms and Abbreviations:

MCHC, mean corpuscular hemoglobin concentration; MCV, mean corpuscular volume; RDW, red cell distribution width; T3, triiodothyronine; T4, thyroxine.

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Table 44–1.Blood Vitamin and Mineral Levels (Adult Values)
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VITAMIN-DEFICIENCY ANEMIAS

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VITAMIN A DEFICIENCY

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Chronic deprivation of vitamin A results in anemia similar to that observed in iron deficiency.1,2,3,4 Mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) are reduced. Anisocytosis and poikilocytosis may be present, and serum iron levels are low. Unlike iron-deficiency anemia, but similar to anemia of chronic disease, iron stores in the liver and marrow are increased, serum transferrin concentration usually is normal or decreased, and administration of medicinal iron does not correct the anemia. However, there is some evidence to suggest that vitamin A deficiency may result in impaired iron absorption or utilization5 and this may be mediated through effects on the expression of genes involved in the regulation of intestinal iron absorption.6 The suggestion that vitamin A may facilitate iron absorption7 was not confirmed.8 Supplementation with vitamin A alone may ameliorate the anemia, although coadministration of vitamin A ...

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