tailieunhanh - Chapter 098. Iron Deficiency and Other Hypoproliferative Anemias

Anemias associated with normocytic and normochromic red cells and an inappropriately low reticulocyte response (reticulocyte index | Chapter 098. Iron Deficiency and Other Hypoproliferative Anemias Anemias associated with normocytic and normochromic red cells and an inappropriately low reticulocyte response reticulocyte index are hypoproliferative anemias. This category includes early iron deficiency before hypochromic microcytic red cells develop acute and chronic inflammation including many malignancies renal disease hypometabolic states such as protein malnutrition and endocrine deficiencies and anemias from marrow damage. Marrow damage states are discussed in Chap. 102. Hypoproliferative anemias are the most common anemias and anemia associated with acute and chronic inflammation is the most common of these. The anemia of inflammation like iron deficiency is related in part to abnormal iron metabolism. The anemias associated with renal disease inflammation cancer and hypometabolic states are characterized by an abnormal erythropoietin response to the anemia. Iron Metabolism Iron is a critical element in the function of all cells although the amount of iron required by individual tissues varies during development. At the same time the body must protect itself from free iron which is highly toxic in that it participates in chemical reactions that generate free radicals such as singlet O2 or OH-. Consequently elaborate mechanisms have evolved that allow iron to be made available for physiologic functions while at the same time conserving this element and handling it in such a way that toxicity is avoided. The major role of iron in mammals is to carry O2 as part of hemoglobin. O2 is also bound by myoglobin in muscle. Iron is a critical element in iron-containing enzymes including the cytochrome system in mitochondria. Iron distribution in the body is shown in Table 98-1. Without iron cells lose their capacity for electron transport and energy metabolism. In erythroid cells hemoglobin synthesis is impaired resulting in anemia and reduced O2 delivery to tissue. Table 98-1 Body Iron .