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What is the function of hemoglobin?
- Oxygen-transporting protein
- Heme portion of Hgb gives the RBCs the characteristic color
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What is the structure of hemoglobin?
- 4 Heme groups: each consisting of a protoporphyrin ring and ferrous (Fe2+) iron
- 4 Globin chains: Alpha, beta, gamma, delta
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What determines the type of hemoglobin?
Amino acid sequence of globin chain
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Where does heme sythesis occur and what is it dependent upon?
- Occurs in the mitochondria of normoblasts
- Dependent on glycine, succinyl coenzyme A, aminolevulinic acid synthesis, and Vit B6
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Where does globin synthesis occur and what controls it?
- Occurs in ribosomes
- Controlled on chromosome 16 for alpha chains and chromosome 11 for all other chains
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What does free hemoglobin bind to and how is it removed?
- Binds to haptoglobin, hemopexin, albumin
- Phagocytized by the liver macrophages
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What lab findings are consistent with the findings:
Increased plasma hemoglobin
Serum bilirubin
Increased serum LD
Increased Urine urobilinogen
Presence of hemoglobinuria and hemosiderinuria
Decreased serum haptoglobin
Occurs when hemoglobin breaks down in the blood and free hemoglobin is released into the plasma
Intravascular hemolysis
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What occurs when senescent/old RBCs are phagocytized by macrophages in the liver or spleen?
Extravascular hemolysis
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What is the protoporphyrin ring metabolized into?
- Metabolized to bilirubin and urobilinogen
- Excreted in the urine and feces
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How are globin chains recycled?
Recycled into the amino acid pool for protein synthesis
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What is the function of iron?
- Binds to transferrin and is transported to the bone marrow for new RBC production
- Stored for future use in the form of ferritin or hemosiderin
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What does serum iron measure?
Amount of Fe3+ bound to transferrin
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What does Total Iron Binding Capacity (TIBC)?
Total amount of iron that transferrin can bind when fully saturated
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What does serum ferritin measure?
Indirect measurement of storage iron in tissues and bone marrow
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What hemoglobin contains:
2 Alpha chains
2 Gamma chains
Hgb F
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What hemoglobin contains:
2 Alpha
2 Beta-globulin chains
Hgb A
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What hemoglobin contains:
2 Alpha
2 Delta globulin chains
Hgb A2
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What is the normal reference range for adults for Hgb A, A2, and F?
- 97% Hgb A
- 2% Hgb A2
- 1% Hgb F
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What is the term for hemoglobin with Fe2+ and O2 and seen in arterial circulation?
Oxyhemoglobin
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What is the term for hemoglobin with Fe2+ but NO O2 and seen in venous circulation?
Deoxyhemoglobin
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What is the term for hemoglobin with Fe2+ and carbon monoxide (CO) and can result in death but is reversible?
Carboxyhemoglobin
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What is the term for hemoglobin with S, caused by drugs and chemicals, and irreversible?
Sulfhemoglobin
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What is the term for hemoglobin with Fe3+ and increased levels cause cyanosis and anemia?
Methemoglobin
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What is the term for the ability of hemoglobin to bind or release oxygen?
Oxygen affinity
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