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Chapter 34 Approach to Anemia in the Adult and Child 459

Proerythroblast Basophilic Polychromatophilic Orthochromatic Reticulocyte
erythroblast erythroblast erythroblast
Fig. 34.1 OVERVIEW OF ERYTHROPOIESIS.

Increased erythropoietin

Hypoxia

Kidney Bone marrow

Iron
Folate
Vitamin B 12

Increased red blood cell production
Fig. 34.2 REGULATION OF ERYTHROPOIESIS.

others). In the latter case of megaloblastic anemia, the BM often is reticulocyte count (see Table 34.2). Other features commonly associ-
packed. However, intramedullary demise of precursors prevents the ated with hemolytic anemia include an elevated lactate dehydrogenase
formation and release of mature RBCs. (LDH) level, increased unconjugated (indirect) bilirubin level, and
By far the most common cause of hypoproliferative anemia glob- decreased haptoglobin level. Hemolytic anemia also may manifest
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ally is iron deficiency. It is estimated that about 2% of infants and with distinctive changes on the peripheral blood smear. Congenital
children may become iron deficient purely because of inadequate causes include the hemoglobinopathies, enzymopathies (predomi-
dietary intake, and that 4% of women ages 20 to 49 years of age in nantly glucose-6-phosphate dehydrogenase [G6PD] deficiency), and
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the United States have iron-deficiency anemia primarily because of membrane disorders. Acquired conditions include autoimmune
inadequate dietary intake in the setting of menstruation and childbirth. hemolytic anemia, microangiopathic hemolytic anemia, hemolysis
Iron deficiency is also commonly encountered in older individuals related to infections, and acquired membrane disorders such as those
as well (~2% of individuals older than age 50 years), and it should caused by liver disease (spur cell of anemia) and paroxysmal nocturnal
provoke a thorough search for its etiology, which in both men and hemoglobinuria. 12
nonmenstruating women frequently is gastrointestinal blood loss. After
iron deficiency, acute or chronic inflammation and renal disease are
8,9
common etiologies of anemia. BM failure states and BM replacement COMPARISON OF ETIOLOGIES OF ANEMIA IN ADULTS
caused by hematologic malignancies or solid tumors are less common AND CHILDREN
causes of anemia and are often accompanied by other hematologic
manifestations, such as leukopenia and thrombocytopenia. As already noted, the designation that anemia is present relies on
comparison of the patient’s hemoglobin or hematocrit with an age-
and sex-appropriate normal range (see Table 34.1). Although many
Hemolytic Anemia types of anemia may occur across the age spectrum, certain types tend
to be identified more commonly in either adults or children, and
The causes of hemolytic anemia are quite varied and may be con- some are primarily identified in neonates. In children, the most
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genital or acquired. The hallmark of hemolytic anemia is an elevated common causes of anemia are related to nutritional deficiency or to