Chapter 098. Iron Deficiency and Other Hypoproliferative Anemias (Part 7)

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The second condition is the anemia of chronic inflammation with inadequate iron supply to the erythroid marrow. The distinction between true irondeficiency anemia and the anemia associated with chronic inflammation is among the most common diagnostic problems encountered by clinicians (see below). Usually the anemia of chronic inflammation is normocytic and normochromic. The iron values usually make the differential diagnosis clear, as the ferritin level is normal or increased and the percent transferrin saturation and TIBC are typically below normal. Finally, the myelodysplastic syndromes represent the third and least common condition. ...

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Chapter 098. Iron Deficiency and Other Hypoproliferative Anemias (Part 7) The second condition is the anemia of chronic inflammation with inadequate iron supply to the erythroid marrow. The distinction between true iron- deficiency anemia and the anemia associated with chronic inflammation is among the most common diagnostic problems encountered by clinicians (see below). Usually the anemia of chronic inflammation is normocytic and normochromic. The iron values usually make the differential diagnosis clear, as the ferritin level is normal or increased and the percent transferrin saturation and TIBC are typically below normal. Finally, the myelodysplastic syndromes represent the third and least common condition. Occasionally, patients with myelodysplasia have impaired hemoglobin synthesis with mitochondrial dysfunction, resulting in impaired iron
incorporation into heme. The iron values again reveal normal stores and more than an adequate supply to the marrow, despite the microcytosis and hypochromia. Iron-Deficiency Anemia: Treatment The severity and cause of iron-deficiency anemia will determine the appropriate approach to treatment. As an example, symptomatic elderly patients with severe iron-deficiency anemia and cardiovascular instability may require red cell transfusions. Younger individuals who have compensated for their anemia can be treated more conservatively with iron replacement. The foremost issue for the latter patient is the precise identification of the cause of the iron deficiency. For the majority of cases of iron deficiency (pregnant women, growing children and adolescents, patients with infrequent episodes of bleeding, and those with inadequate dietary intake of iron), oral iron therapy will suffice. For patients with unusual blood loss or malabsorption, specific diagnostic tests and appropriate therapy take priority. Once the diagnosis of iron-deficiency anemia and its cause is made, there are three major therapeutic approaches. Red Cell Transfusion Transfusion therapy is reserved for individuals who have symptoms of anemia, cardiovascular instability, continued and excessive blood loss from whatever source, and require immediate intervention. The management of these
patients is less related to the iron deficiency than it is to the consequences of the severe anemia. Not only do transfusions correct the anemia acutely, but the transfused red cells provide a source of iron for reutilization, assuming they are not lost through continued bleeding. Transfusion therapy will stabilize the patient while other options are reviewed. Oral Iron Therapy In the asymptomatic patient with established iron-deficiency anemia, treatment with oral iron is usually adequate. Multiple preparations are available, ranging from simple iron salts to complex iron compounds designed for sustained release throughout the small intestine (Table 98-5). While the various preparations contain different amounts of iron, they are generally all absorbed well and are effective in treatment. Some come with other compounds designed to enhance iron absorption, such as ascorbic acid. It is not clear whether the benefits of such compounds justify their costs. Typically, for iron replacement therapy, up to 300 mg of elemental iron per day is given, usually as three or four iron tablets (each containing 50–65 mg elemental iron) given over the course of the day. Ideally, oral iron preparations should be taken on an empty stomach, since foods may inhibit iron absorption. Some patients with gastric disease or prior gastric surgery require special treatment with iron solutions, since the retention capacity of the stomach may be reduced. The retention capacity is necessary for dissolving the shell of the iron tablet before the release of iron. A dose of 200–300 mg of
elemental iron per day should result in the absorption of iron up to 50 mg/d. This supports a red cell production level of two to three times normal in an individual with a normally functioning marrow and appropriate erythropoietin stimulus. However, as the hemoglobin level rises, erythropoietin stimulation decreases, and the amount of iron absorbed is reduced. The goal of therapy in individuals with iron-deficiency anemia is not only to repair the anemia, but also to provide stores of at least 0.5–1.0 g of iron. Sustained treatment for a period of 6–12 months after correction of the anemia will be necessary to achieve this. Table 98-5 Oral Iron Preparations Generic Name Tablet (Iron Elixir (Iron Content), Content), mg mg in 5 mL Ferrous sulfate 325 (65) 300 (60) 195 (39) 90 (18) Extended release 525 (105) Ferrous fumarate 325 (107)
195 (64) 100 (33) Ferrous 325 (39) 300 (35) gluconate Polysaccharide 150 (150) 100 (100) iron 50 (50)