Transcript Chapter_026.ppt

Chapter 26
Alterations of Erythrocyte Function
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Alterations in Erythrocytes
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Too many cells
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Too few cells
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Polycythemias
Anemias
Normal number of cells with altered
components
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Anemia
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Reduction in the total number of erythrocytes
in the circulating blood or in the quality or
quantity of hemoglobin
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Impaired erythrocyte production
 Acute or chronic blood loss
 Increased erythrocyte destruction
 Combination of the above
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Anemia
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Classifications
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Etiology
Morphology
• Based on MCV, MCH, and MCHC values
• Size
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Identified by terms that end in “-cytic”
Macrocytic, microcytic, normocytic
• Hemoglobin content
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Identified by terms that end in “-chromic”
Normochromic and hypochromic
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Anemia
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Anisocytosis
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Red cells are present in various sizes
Poikilocytosis
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Red cells are present in various shapes
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Anemia
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Physiologic manifestation
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Variable symptoms based on severity and the
ability of the body to compensate
Classic anemia symptoms
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Reduced oxygen carrying capacity
Fatigue, weakness, dyspnea, and pallor
Other
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Due to hypoxemia and tissue hypoxia
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Anemia
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Cardiovascular function
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Respiratory function
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Dyspnea
Nervous system function
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Increased preload, heart rate, and stroke volume;
reduced afterload
Myelin degeneration
Gastrointestinal function
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Pain, nausea, vomiting, anorexia
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Normochromic-Macrocytic
Anemias
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Also termed megaloblastic anemias
Defective DNA synthesis
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Due to deficiencies in vitamin B12 or folate
• Coenzymes for nuclear maturation and the DNA
synthesis pathway
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Ribonucleic acid (RNA) processes occur at a
normal rate
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Results in unequal growth of the nucleus and
cytoplasm
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Normochromic-Macrocytic
Anemias
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Pernicious anemia
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Caused by a lack of intrinsic factor from the gastric
parietal cells
Required for vitamin B12 absorption
Results in vitamin B12 deficiency
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Normochromic-Macrocytic Anemias
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Pernicious anemia
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Typical anemia symptoms
Neurologic manifestations
• Nerve demyelination
Loss of appetite, abdominal pain, beefy red tongue
(atrophic glossitis), icterus, splenic enlargement
Treatment
• Parenteral or high oral doses of vitamin B12
Often unrecognized in older adults due to subtle, slow
onset and presentation
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Pernicious Anemia
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Normochromic-Macrocytic
Anemias
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Folate deficiency anemia
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Absorption of folate occurs in the upper small
intestine
Not dependent on any other facilitating factor
Similar to pernicious anemia except neurologic
manifestations generally not seen
Treatment requires daily oral administration of folate
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Hypochromic-Microcytic Anemias
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Characterized by red cells that are
abnormally small and contain reduced
amounts of hemoglobin
Related to:
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Disorders of iron metabolism
 Disorders of porphyrin and heme synthesis
 Disorders of globin synthesis
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Hypochromic-Microcytic Anemias
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Iron deficiency anemia
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Most common type of anemia worldwide
Nutritional iron deficiency
Metabolic or functional deficiency
Progression of iron deficiency causes:
• Brittle, thin, coarsely ridged, spoon-shaped nails
• A red, sore, painful tongue
Symptomtic Hgb 7-8 g/dl
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Hypochromic-Microcytic Anemias
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Sideroblastic anemia
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Group of disorders characterized by anemia
Altered mitochondrial metabolism causing
ineffective iron uptake and resulting in
dysfunctional hemoglobin synthesis
Ringed sideroblasts within the bone marrow are
diagnostic
• Sideroblasts are erythroblasts that contain iron granules
that have not been synthesized into hemoglobin
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Hypochromic-Microcytic Anemias
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Sideroblastic anemia
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Dimorphism
Myelodysplastic syndrome
Erythropoietic hemochromatosis
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Normochromic-Normocytic
Anemias
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Characterized by red cells that are relatively
normal in size and hemoglobin content but
insufficient in number
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Normochromic-Normocytic
Anemias
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Aplastic anemia
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Pancytopenia
Pure red cell aplasia
Fanconi anemia
Posthemorrhagic anemia
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Acute blood loss from the vascular space
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Normochromic-Normocytic
Anemias
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Hemolytic anemia
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Accelerated destruction of red blood cells
 Autoimmune hemolytic anemias
 Immunohemolytic anemia
 Warm antibody immunohemolytic anemia
 Drug-induced hemolytic anemia
 Cold agglutinin immunohemolytic anemia
 Cold hemolysin hemolytic anemia
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Drug-Induced Hemolytic Anemia
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Normochromic-Normocytic
Anemias
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Sickle cell anemia
Anemia of chronic inflammation
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Mild to moderate anemia seen in:
• AIDS, rheumatoid arthritis, lupus erythematosus, hepatitis,
renal failure, and malignancies
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Pathologic mechanisms
• Decreased erythrocyte life span
• Ineffective bone marrow response to erythropoietin
• Altered iron metabolism
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Anemia of Chronic Inflammation
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Myeloproliferative RBC Disorders
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Polycythemia
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Overproduction of RBCs
Relative polycythemia
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Result of dehydration
Fluid loss results in relative increases of red cell
counts and Hb and Hct values
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Polycythemia
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Absolute polycythemia
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Primary absolute
• Abnormality of stem cells in the bone marrow
• Polycythemia vera (PV)
Secondary absolute
• Increase in erythropoietin as a normal response to
chronic hypoxia or an inappropriate response to
erythropoietin-secreting tumors
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