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Questions and Answers
What is the most common cause of vitamin B12 deficiency?
What is the primary mechanism of folic acid absorption?
What is the typical presentation of megaloblastic anemia?
What is the treatment for pernicious anemia?
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What is the primary cause of pernicious anemia?
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What is the daily requirement of folic acid?
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What is the most common cause of Folate deficiency?
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Which of the following is a clinical feature of megaloblastic anemia due to Folate deficiency?
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Which of the following increases the requirement for Folate?
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What is the earliest symptom of neurological dysfunction due to Vitamin B12 deficiency?
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Which of the following drugs can impair the utilization of Folate?
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What is the pathology of neurological dysfunction due to Vitamin B12 deficiency?
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What is the primary cause of megaloblastic anemia?
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What is the characteristic feature of erythroblasts in megaloblastic anemia?
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What is the effect of vitamin B12 deficiency on DNA synthesis?
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What is the treatment for megaloblastic anemia?
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What is the effect of folic acid deficiency on erythropoiesis?
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What is the hallmark of non-megaloblastic macrocytosis?
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Study Notes
Macrocytosis and Megaloblastic Anemia
- Macrocytosis is a condition where red blood cells (RBCs) are larger than normal, with a mean corpuscular volume (MCV) > 100 fl.
Non-Megaloblastic Macrocytosis
- Causes include:
- RBC membrane abnormalities (e.g., liver disease, myxedema, alcoholism)
- Aplastic anemia
- Myelodysplastic syndrome (MDS)
- Acquired sideroblastic anemia
- Reticulocytosis
- Pregnancy and newborns
Megaloblastic Anemia
- Characterized by high MCV (>120 fl) and defective DNA synthesis
- Erythroblasts are larger than normal with immature nuclei (nuclear-cytoplasmic asynchrony)
- Causes include:
- Deficiency of vitamin B12 and/or folic acid (most common)
- Drugs that interfere with DNA nucleotide base synthesis (e.g., purine analogues, pyrimidine analogues)
- Intrinsic factor deficiency
- Certain diseases (e.g., Crohn's disease, pancreatic insufficiency)
Vitamin B12 Deficiency
- Causes include:
- Dietary deficiency (rare, e.g., vegans)
- Poor absorption (most common cause)
- Malabsorption (e.g., pernicious anemia, gastrectomy, old age)
- Certain infections (e.g., Diphyllobothrium latum, Helicobacter pylori)
- Certain drugs (e.g., proton pump inhibitors)
Pernicious Anemia
- A type of megaloblastic anemia caused by autoimmune chronic gastritis
- Common in Caucasians, both genders, and those with a family history
- Typically presents at age 60 years
- Associated with other autoimmune disorders (e.g., blue eyes, premature graying, vitiligo)
Folic Acid (Folate)
- A water-soluble vitamin essential for DNA synthesis
- Abundant in vegetables, fruits, dairy products, and liver
- Natural folates are in polyglutamate form, which is converted to monoglutamate for absorption
- Absorption occurs in the jejunum
- Requirement: 100 µg/day
- Body stores: 10 mg in the liver (can last 4 months or less in alcoholics)
Folate Deficiency
- Causes include:
- Dietary deficiency (most common)
- Impaired absorption (e.g., celiac disease, resection)
- Impaired utilization (e.g., certain drugs, alcohol)
- High requirement (e.g., pregnancy, dialysis, hemolysis)
- High loss (e.g., heart failure, chronic liver disease)
Clinical Features of Megaloblastic Anemia
- Chronic and asymptomatic, with insidious onset
- Non-specific symptoms: burning tongue, weight loss, diarrhea, sterility, impotence
- Depression, Alzheimer disease, atherosclerosis, and thrombosis
- Signs: pallor, mild jaundice, glossitis, smooth red beefy tongue, aphthous ulcers, hyperpigmentation, and splenomegaly
Neurological Dysfunction in Vitamin B12 Deficiency
- Pathology: subacute combined degeneration of the spinal cord
- Demylination and axonal degeneration can occur at any time
- Severity is inversely related to anemia
- Sensory and motor deficits, with parasthesia in distal limbs as the earliest symptom
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Description
Explore the world of anemia! This quiz covers the causes of macrocytosis, B12 and folate metabolism, diagnosis, and treatment of megaloblastic anemia. Test your knowledge and revise your understanding of this important topic in hematology.
