Hemoglobin, iron binding

Example In the protein hemoglobin, iron binds to O2 to transport oxygen from the limgs to the rest of the body. 

Figure 38-4. Examples of three types of missense mutations resulting in abnormal hemoglobin chains. The amino acid alterations and possible alterations in the respective codons are indicated. The hemoglobin Hikari p-chain mutation has apparently normal physiologic properties but is electrophoretically altered. Hemoglobin S has a p-chain mutation and partial function hemoglobin S binds oxygen but precipitates when deoxygenated. Hemoglobin M Boston, an a-chain mutation, permits the oxidation of the heme ferrous iron to the ferric state and so will not bind oxygen at all.

Hematological Methods. Hematological analyses can Include the determination of the total hemoglobin concentration (In g%), the packed cell volume (PCV In %), the red blood cell count (In 10 /mm ) and reticulocytes count (In %), calculation of the red cell Indices, examination of a blood film, tests to demonstrate the presence of Inclusion bodies and of sickle cells, tests to evaluate the distribution of fetal hemoglobin (Hb-F) Inside the red cells, the red cell osmotic fragility, the concentration of serum Iron (SI), total Iron binding capacity (TIBC), and the survival time of the red cells. Details of all... 

Iron is, as part of several proteins, such as hemoglobin, essential for vertebrates. The element is not available as ion but mostly as the protein ligands transferrin (transport), lactoferrin (milk), and ferritin (storage), and cytochromes (electron transport) (Alexander 1994). Toxicity due to excessive iron absorption caused by genetic abnormalities exists. For the determination of serum Fe a spectrophoto-metric reference procedure exists. Urine Fe can be determined by graphite furnace (GF)-AAS, and tissue iron by GF-AAS and SS-AAS (Alexander 1994 Herber 1994a). Total Iron Binding Capacity is determined by fuUy saturated transferrin with Fe(III), but is nowadays mostly replaced by immunochemical determination of transferrin and ferritin. 

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. 

F, female M, male MCH, mean corpuscular hemoglobin MCHC, mean corpuscular hemoglobin concentration MCV, mean corpuscular volume RBC, red blood cell RDW, red blood cell distribution TIBC, total iron-binding capacity. 

Brydon and Roberts- added hemolyzed blood to unhemolyzed plasma, analyzed the specimens for a variety of constituents and then compared the values with those in the unhemolyzed plasma (B28). The following procedures were considered unaffected by hemolysis (up to 1 g/100 ml hemoglobin) urea (diacetyl monoxime) carbon dioxide content (phe-nolphthalein complex) iron binding capacity cholesterol (ferric chloride) creatinine (alkaline picrate) uric acid (phosphotungstate reduction) alkaline phosphatase (4-nitrophenyl phosphate) 5 -nucleotidase (adenosine monophosphate-nickel) and tartrate-labile acid phosphatase (phenyl phosphate). In Table 2 are shown those assays where increases were observed. The hemolysis used in these studies was equivalent to that produced by the breakdown of about 15 X 10 erythrocytes. In the bromocresol green albumin method it has been reported that for every 100 mg of hemoglobin/100 ml serum, the apparent albumin concentration is increased by 100 mg/100 ml (D12). Hemolysis releases some amino acids, such as histidine, into the plasma (Alb). 

Hemoglobin, hematocrit, reticulocyte count, ferritin and serum iron levels, and total iron-binding capacity... 

MCV, mean cell volume MCHC, mean cell hemoglobin concentration SI, serum iron TIBC, transferrin iron-binding capacity. 

Figure 9.3 The iron-containing heme group on hemoglobin that binds with molecular oxygen and enables red blood cells to carry oxygen to tissues.

Under normal circumstances, transferrin is one-fourth to one-third saturated with iron. The level of saturation may decrease in systemic infection or cancer and in iron deficiency anemia, the most common nutritional deficiency in the United States. In individuals with iron deficiency anemia, transferrin levels are increased. The level of saturation with iron increases in iron overload syndromes such as hereditary hemochromatosis or as a result of repeated blood transfusions, as is the case in thalassemia patients. Determinations of total plasma iron (TI) and plasma total iron binding capacity (TIBC) are routinely performed in the clinical biochemistry laboratory. The TIBC value reflects transferrin levels in plasma the amount of iron that can be bound by transferrin is equal to TIBC x 0.7. Total plasma iron levels in iron deficiency anemia become abnormal before hemoglobin levels show any change. 

Deferoxamine derives from Streptomyces pilosus. The substance possesses a very high iron-binding capacity but does not withdraw iron from hemoglobin or cytochromes. It is poorly absorbed enterally and must be given parenterally to cause increased excretion of iron. Oral administration is indicated only if enteral absorption of iron is to be curtailed. Unwanted effects include allergic reactions. 

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