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7 Cards in this Set
- Front
- Back
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Megaloblastic Anemia
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Called megaloblastic due to presence of blasts = larger RBC caused by asynchronous maturation of cytoplasm and nucleus. (Folate/Vit. B₁₂ deficiency)
Reduced levels of DNA synth ➔ decreased rate of nucleus maturation ➔ less condensed chromatin/nucleus still in RBC ➔ more Hb/cytoplasm |
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Erythropoiesis
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Marrow pushes oldest cells out first in anemic conditions
RBC → Retic → Shift Retic → Metarubicyte (nucleated RBC) Stimulated by erythropoietin. Shift retic - released at least one day early |
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WBC Development
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Myeloblast ➔ Promyelocyte ➔ Myelocyte ➔ Metamyelocyte ➔ Bands/Stabs ➔ Mature leukocyte
Bacterial infection = pt. comes w/ fever and left shift (more bands) Viral infection/leukemia = leukocytosis |
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Vit B₁₂ Metabolism
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R binding protein binds Vit. B₁₂ and passes through stomach ➔ R binding protein removed by pancreatic enzyme in duodenum, allows IF to bind Vit. B₁₂
➔ IF-Vit B₁₂ binds to receptor sites in ileum and is absorbed. Important in formation of homocystine ➔ Methionine formation of Succinyl-CoA Folate def. is more common - less amount of stores |
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Folate Trap
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Unable to take methyl off THF ➔ ⬆ [homocystine] = Not enough Vit B₁₂, folate levels are ok
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Pernicious Anemia
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Achlorhydria (lack of gastric acid due to destruction of parietal cells)
Maldigestion Normally makes Fe in 2+ state, but under these conditions it is not, so will also have microcytes Hypergastrinemia – excess gastrin (stimulates secretion of HCl) Type II hypersensitivity (Immune response) Ab against proton pump in parietal cells Ab block Vit. B12 binding to IF Ab prevent binding of Vit. B12 – F complex to ileal receptors Ab destroy parietal cells Chronic atrophic gastritis ⬆ incidence of gastric adenocarcinoma |
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Lab Values for Megaloblastic Anemia
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MCV > 100
MCHC = upper range ⬇ serum vit. B₁₂/folate (serum folate is not a good test – masked by diet ex. Fruit/vegetables. Use ⬇ RBC folate instead) ⬆ Homocysteine (vit. B₁₂/folate deficiency) (hyperhomocysteninemia = cardiovasc. problems) ⬆ methylmalonic acid (vit. B₁₂ deficiency) ⬆ LDH1 in Vit. B₁₂ Smear (Vit. B₁₂/Folate deficiency) Pancytopenia Oval Macrocytes Hypersegmented neutrophils (more than 5 lobes) |
