Megaloblastic Anemias
Terms
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Megaloblastic Anemia:
Biochemical Abnormality
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- Thymidine monophosphate (TMP) is needed for normal DNA synthesis
- Decreases in TMP synthesis from uridine monophosphate (UMP) results in abnormal DNA synthesis
- Defective nuclear maturation and megaloblastic morphology
- im
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Megaloblastic Anemia - Etiology
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- Vitamin B12 deficiency
- Folicacid deficiency
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Megaloblastic Anemia- Clinical features
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- fatigue
- weakeness
- shortness of breath
- lightheadedness
- some jaundice in severe cases due to increased bilirubin
- congestive heart failure possible in severe cases
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Megaloblastic Anemia: Bone marrow
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- ineffective hematopoiesis in RBC, WBC, platelets
- hypercellular marrow: bone marrow making more because of lack of proper growth
- M:E ratio can be from 1:1 to 1:3
- Asynchronous development between nucleus and cytoplasm
- Megaloblastic Anemia: Maturation
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- Promegaloblas
- big hoff
- stain more acid because bigger nucleus
- Basophilic megaloblast
- red, young nucleus lagging behind--> not making enough DNA (lack TMP)
- polychromatic megal
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Megaloblastic Anemia: Peripheral Blood
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- Erythrocyte
- macrocytic, normochromic
- RBC: 1-3 x10^6/ul; Hgb: 6-9 g/dl; Hct: 20-30%
- MCV: 100-160 fL; MCH: increased; MCHC: normal
- Morphology: macrocytes, macroovalocytes, A&P, decreased reticulocyte count, RB
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Vitamin B12
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- produced by microorganisms and fungi
- liver, fish, poultry, meat, eggs
- Intake:
- 5-30 ug/day
- dependent on body's needs
- 1-5 ug/day absorbed
- Body stores 1-5 mg Vit B12
- B12 loss is ab
- Vitamin B12 deficiency- Etiology
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- Dietary
- poor diet
- mothers who are strict vegetarian may have children who are deficient
- malabsorption
- pernicious anemia
- decreased Instrinsic Factor due to parietal cell atrophy
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Vitamin B12 deficiency- Clinical features
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- typical megaloblastic picture in bone marrow and blood
- Neurological problems
- degeneration of peripheral nerves
- degeneration of spinal cord
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Folic Acid - Source
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- water-soluble vitamin
- green, leafy veggies
- fruits, dairy products, cereals,
- liver, kidney
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Folic Acid- Nutritional requirements
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- Intake
- 400-600 ug/day in avg diet
- 50-100 ug/day recommended
- depend on body's needs
- overcooking foods destroys folic acid and causes deficiency
- Body stores 5-10 mg in many tissues
- takes o
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Folic Acid- Etiology
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- Dietary
- poverty, agine
- alcoholism
- Malabsorption
- tropical sprue
- Increased requirement
- pregnancy, infancy
- cancer
- Drugs
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Folic Acid- Clinical features
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- typical megaloblastic picture in bone marrow and blood
- neurological problems
- not as severe as in B12
- depressio, dementia in some
- Lab findings for B12 and Folic Acid Deficiencies
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- serum B12 levels
- serum and RBC folate levels
- Antibodies to IF
- Schilling's test evaluates B12 absorption from GI tract (radioactive test)
- Vitamin B12 deficiency
- oral therapy
- injections
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Non-Megaloblastic Causes of Macrocytosis
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- chronic liver disease
- alcoholism
- acute hemorrhage: lose B12 and folate in RBC, speed up RBC butr not right size