Hemoglobin iron metabolism

Decreased red blood cell (RBC) count, hemoglobin (Hgb) and hematocrit (Hct) iron metabolism may also be altered [iron level, total iron binding capacity (TIBC), serum ferritin level, and transferrin saturation (TSAT)]. Erythropoietin levels are not routinely monitored and are generally normal to low. Urine positive for albumin or protein. 

Copper in potatoes varies from 0.23 to 11.9mg/kg FW (Randhawa et al., 1984 Rivero et al., 2003). Like zinc, copper is also high in yellow-fleshed potatoes (Dugo et al., 2004). Copper is needed for synthesis of hemoglobin, proper iron metabolism, and maintenance of blood vessels. The US RDA is 1.5-3.0mg. 

Anemia may result from other complications even when iron supply is sufficient. A decrease in hemoglobin synthesis, a fault in transport mechanisms or destruction of erythrocytes have all been noted. Sideroblastic or iron-loading anemias are characterized by a fault in iron metabolism (see Section 62.2.3.2). There are also several other syndromes of iron deficiency known clinically, including pica and Goodpasture s syndrome (an immune-related lung and kidney disease). The different categories of anemia have been discussed in detail by Prasad.48... 

RNA secondary structure plays a role in the regulation of iron metabolism in eukaryotes. Iron is an essential nutrient, required for the synthesis of hemoglobin, cytochromes, and many other proteins. However, excess iron can be quite harmful because, untamed by a suitable protein environment, iron can initiate a range of free-radical reactions that damage proteins, lipids, and nucleic acids. Animals have evolved sophisticated systems for the accumulation of iron in times of scarcity and for the safe storage of excess iron for later use. Key proteins include transferrin, a transport protein that carries iron in the serum, transferrin receptor, a membrane protein that binds iron-loaded transferrin and initiates its entry into cells, and ferritin, an impressively efficient iron-storage protein found primarily in the liver and kidneys. Twenty-four ferritin polypeptides form a nearly spherical shell that encloses as many as 2400 iron atoms, a ratio of one iron atom per amino acid (Figure 31.37). 

There is some evidence that ceruloplasmin is involved in iron metabolism. It has been suggested that ceruloplasmin and ferritin in plasma work together to reduce the levels of free ferrous ions in plasma. Here, the ceruloplasmin catalyzes the oxidation of Fe (ferrous) to (ferric), the form of the metal that binds to ferritin. Ceruloplasmin acts as an oxidant in this process. This proposed function may reduce damage to membrane lipids possibly inflicted by the small amount of Fe in the circulation. It is thought that ceruloplasmin may be used in the mobilization of iron from intracellular stores. Here, the protein may facilitate the transfer of iron from ferritin to transferrin [Frieden and Hsieh, 1976), A relationship between copper and irtm is suggested by the fact that copper-deficient rats may develop iron deficiency anemia, as revealed by measurements of hemoglobin and hematocrit (Johnson and Dufault, 19S9 Cohen et a ., 1985), Ceruloplasmin may also function in a unique iron transport mechanism, as mentioned in the Iron section. 

It has been known for some time that copper deficiency leads to anemia and failure of the erythropoietic system to matiure (50,51). Although the exact mechanism involved is still not well defined, recent evidence suggests that copper may be essential for iron absorption and mobilization for hemoglobin synthesis. A ferrous-to-ferric cycle with respect to the role of copper in iron metabolism has been proposed by several workers. Role of ceruloplasmin in the spontaneous oxidation of... 

Iron Metabolism. Copper-containing enzymes— namely ferroxidase I (ceruloplasmin) and ferroxidase II, and the recently described hephaestin in the enterocyte—oxidize ferrous iron to ferric iron. This allows incorporation of Fe into transferrin and eventually into hemoglobin. Ferroxidase II is a yellow protein, the importance of which in iron metabolism is not as well characterized as that of ceruloplasmin. 

High fiber diets administered to patients suffering from diverticular disease did not lower hemoglobin concentrations over a six month period (Brodribb and Humphreys/ 42) Prolonged consumption of vegetar ian diets which are inherently rich in dietary fiber did not impair iron metabolism as judged by hematologic criteria (48,58). 

Copper is extremely important for the proper functioning of the body. It aids in the absorption of iron from the intestine and facilitates iron metabolism. It is critical for the formation of hemoglobin and red blood cells in the bone marrow. Copper is also necessary for the synthesis of collagen, a protein that is a major component of the cormective tissue. It is essential to the central nervous system in two important ways. First, copper is needed for the synthesis of norepinephrine and dopamine, two chemicals that are necessary for the transmission of nerve signals. Second, it is required for the deposition of the myelin sheath (a layer of insulation) around nerve cells. Release of cholesterol from the Uver depends on copper, as does bone development and proper function of the immune and blood clotting systems. 

Fig. 44.6. Iron metabolism. Iron is absorbed from the diet, transported in the blood in transferrin, stored in ferritin, and used for the synthesis of cytochromes, iron-containing enzymes, hemoglobin, and myoglobin. It is lost from the body with bleeding and sloughed-off cells, sweat, urine, and feces. Hemosiderin is the protein in which excess iron is stored. Small amounts of ferritin enter the blood and can be used to measure the adequacy of iron stores. RE = reticuloendothelial.

Hemosiderosis is a form of siderosis in which the iron deposits result from hemoglobin breakdown. Hemosiderosis may be focal (a consequence of hemorrhage) or generalized, resulting from a reduced life span of the red cell (repeated blood transfusion, hemolytic anemia, etc.). Hemochromatosis is characterized by cirrhosis, diabetes, and skin pigmentation and probably results from some molecular alteration of iron metabolism. Hemochromatosis will be described in more detail after a discussion of the iron pigments in tissues. 

In hemochromatosis, hemosiderin accumulates in many tissues. The origin of the hemosiderin found in hemachromatosis is not established, but it does not come from hemoglobin breakdown, and hemochromatosis probably is a disease of iron metabolism [33-37]. 

Figure 1 Iron metabolism and balance inputs, losses, and recycling of iron through the reticuloendothelial system. Fe, iron Tf, transferrin Hb, hemoglobin RBC, red blood cell RE, reticuloendothelial.

Iron is another vital nutrient in the development of functioning erythrocytes it is essential for the formation of hemoglobin. Lack of iron leads to a decrease in hemoglobin synthesis and ultimately red blood cells. Normal homeostasis of iron transport and metabolism is depicted in Fig. 63-2.7 Approximately 1 to 2 mg of iron is absorbed through the duodenum each day, and the same amount is lost via blood loss, desquamation of mucosal cells, or menstruation. 

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