Vitamin B12 and Anemia Quiz
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Questions and Answers

What is the correct name for the vitamin B12 deficiency anemia?

  • Megaloblastic Anemia
  • Periorbital Anemia
  • Pernicious Anemia (correct)
  • Macrocytic Anemia

    • What is the function of vitamin B12 that makes it important for the prevention of anemia?

  • It is a vital component of the electron transport chain in mitochondria.
  • It plays a crucial role in DNA synthesis and cell division. (correct)
  • It is a key component of coenzyme A, crucial for carbohydrate metabolism.
  • It assists in the conversion of phenylalanine to tyrosine.

    • Which of the following is NOT a cause of non-megaloblastic macrocytic anemia?

  • Liver dysfunction
  • Folate deficiency (correct)
  • Myelodysplastic Syndrome
  • Alcoholism

    • What is the minimum value of MCV (Mean Corpuscular Volume) for a patient to potentially be diagnosed with macrocytic anemia?

    <p>100fL (B)</p> Signup and view all the answers

    What are the primary sources of dietary vitamin B12? (Select all that apply)

    <p>Dairy products (B), Meat and fish (C)</p> Signup and view all the answers

    What is the typical treatment regimen for pernicious anemia?

    <p>Intramuscular injection of Vitamin B12 (B)</p> Signup and view all the answers

    What is the common characteristic feature of megaloblastic anemias?

    <p>Increased red blood cell size (B)</p> Signup and view all the answers

    Which of the following is NOT a known cause of folate deficiency?

    <p>Increased production of red blood cells (B)</p> Signup and view all the answers

    Which of the following tests is NOT typically used to diagnose alcoholism in a patient with macrocytosis?

    <p>Complete Blood Count (C)</p> Signup and view all the answers

    How does hypothyroidism contribute to the development of anemia?

    <p>Reducing the production of erythropoietin (A)</p> Signup and view all the answers

    What is the primary mechanism by which certain drugs can cause anemia?

    <p>Interfering with folate or vitamin B12 metabolism (D)</p> Signup and view all the answers

    What is the recommended serum folate level for diagnosing folate deficiency?

    <p>2 ng/mL (A)</p> Signup and view all the answers

    What is the primary role of methylmalonic acid in the context of vitamin B12 deficiency?

    <p>It is a marker for vitamin B12 deficiency (A)</p> Signup and view all the answers

    What role does intrinsic factor play in the absorption of vitamin B12?

    <p>Intrinsic factor binds to vitamin B12 and facilitates its absorption in the small intestine. (A)</p> Signup and view all the answers

    What is the primary function of vitamin B12 in the body?

    <p>Vitamin B12 is involved in the production of red blood cells and the synthesis of DNA. (B)</p> Signup and view all the answers

    Identify the primary site of vitamin B12 absorption in the digestive tract.

    <p>Terminal Ileum (C)</p> Signup and view all the answers

    Which of the following is NOT a common neurological symptom associated with vitamin B12 deficiency?

    <p>Hyperreflexia (B)</p> Signup and view all the answers

    What is the relationship between folic acid and vitamin B12 in the body?

    <p>Vitamin B12 is required to convert folic acid to its active form, 5-methyltetrahydrofolate, which is crucial for DNA synthesis. (C)</p> Signup and view all the answers

    Which of the following laboratory findings is NOT consistent with megaloblastic anemia caused by vitamin B12 deficiency?

    <p>Increased serum ferritin levels (A)</p> Signup and view all the answers

    What is the significance of hypersegmented neutrophils in a peripheral blood smear?

    <p>Hypersegmented neutrophils indicate a deficiency in vitamin B12 or folic acid. (C)</p> Signup and view all the answers

    Which of the following is NOT a potential cause of vitamin B12 deficiency?

    <p>Hyperthyroidism (B)</p> Signup and view all the answers

    Why is homocysteine elevated in both B12 and folate deficiency?

    <p>Both B12 and folate are required for the conversion of homocysteine to methionine. (C)</p> Signup and view all the answers

    Which of the following is NOT a possible cause of a low reticulocyte count in a patient with both normal B12 and folate levels?

    <p>Hemolysis (C)</p> Signup and view all the answers

    Which of the following biochemical tests is NOT typically used to rule out hemolysis?

    <p>Creatinine kinase (A)</p> Signup and view all the answers

    A patient has a hematocrit of 35% and a red blood cell count of 5.0 x 10^6 cells/uL. What is their MCV and what type of anemia do they have?

    <p>MCV = 70 fL, Microcytic anemia (D)</p> Signup and view all the answers

    A patient has a hemoglobin of 12.5 g/dL, a hematocrit of 42%, and a red blood cell count of 4.2 x 10^6 cells/uL. Calculate the MCHC. What is the diagnosis based on the MCHC and the MCV you calculate?

    <p>MCHC = 30.8 g/dL, Normocytic anemia (D)</p> Signup and view all the answers

    A patient has a hemoglobin of 12.5 g/dL, a hematocrit of 37%, and a red blood cell count of 4.2 x 10^6 cells/uL. What is their MCV and MCHC, and what type of anemia do they have?

    <p>MCV = 88 fL, MCHC = 29.8 g/dL, Normocytic anemia (B)</p> Signup and view all the answers

    Which of the following statements accurately describes the relationship between B12, folate, and homocysteine?

    <p>Both B12 and folate are involved in the conversion of homocysteine to methionine, so deficiencies in either can lead to elevated homocysteine levels. (C)</p> Signup and view all the answers

    A patient has a high reticulocyte count and normal B12 and folate levels. Which of the following is the most likely cause?

    <p>Hemolysis or blood loss (D)</p> Signup and view all the answers

    Study Notes

    Macrocytic Anemia

    • Macrocytic anemia is characterized by a high Mean Corpuscular Volume (MCV)
    • Anemia is defined as a hemoglobin (Hb) level below normal
      • Male: <13.94 g/L
      • Female:<11 g/L
    • MCV is greater than 100 fL

    Etiology of Macrocytic Anemia

    • Two main categories:
      • Megaloblastic
        • Vitamin B12 deficiency/impairment of utilization
        • Folate deficiency/impairment of utilization
        • Liver dysfunction
        • Some drug usage
      • Non-megaloblastic
        • Alcoholism
        • Myelodysplastic syndrome (MDS)
        • Hypothyroidism

    Megaloblastic Anemia - Vitamin B12 Deficiency

    • Sources: Meat, fish, eggs, dairy products
    • Also known as pernicious anemia
    • Function: RBC formation, DNA synthesis, maintaining neurological function
    • Causes:
      • Dietary deficiency
      • Malabsorption
      • Congenital disorders
      • Gastrectomy

    Vitamin B12 Absorption

    • Vitamin B12 binds to intrinsic factor (IF) secreted by gastric parietal cells
    • Absorbed in the terminal ileum
    • Once absorbed, it acts as a coenzyme to produce methionine (from homocysteine)
    • Folic acid is converted to its active form (5-methyltetrahydrofolate)
    • Impairs DNA synthesis

    Sign and Symptoms

    • Fatigue
    • Headache
    • Palpitations
    • Dyspnea
    • Gray hair
    • Neurological symptoms (e.g., paresthesia, hypoesthesia)

    Peripheral Blood

    • Microscopic Observation
      • Presence of hypersegmented neutrophils (more than 6 lobes)
      • Macro-ovalocytes
      • Anisocytosis
    • Bone Marrow Biopsy
      • Hypercellularity with abnormal maturation of myeloid cell lines.

    Blood Smear

    • Hypersegmented RBCs
    • Macrocytosis

    Laboratory Findings

    • Biochemical results (evidence of hemolysis)
      • High Lactate dehydrogenase (LDH) level
      • High indirect bilirubin level
      • Decreased haptoglobin level
    • Treatment: Parenteral administration of vitamin B12, restoring hematological levels to normal within a month.

    Megaloblastic Anemia - Pernicious Anemia

    • Characteristic:
      • Lack of intrinsic factor
      • Destruction of gastric parietal cells
      • Detection of antigastric parietal cell autoantibodies
    • Treatment: Lifelong administration of vitamin B12 (intramuscular injection and high oral doses).

    Pernicious Anemia - Vitamin B12 Absorption Failure

    • In normal conditions, B12 is absorbed from the gut.
    • In pernicious anemia, the parietal cells fail to secrete intrinsic factor (IF), preventing B12 absorption.

    Megaloblastic Anemia - Folate Deficiency

    • Folate is also known as folic acid or folacin
    • Sources: Green vegetables and animal products
    • Absorbed in the upper jejunum via passive and active diffusion
    • Causes:
      • Nutritional deficiency
      • Malabsorption
      • Medication
    • Treatment: Oral folic acid for nutritional deficiencies

    Role of Vitamin B12 and Folate in DNA Synthesis

    • Detailed steps involved in the sequential reactions of folate and B12 in the synthesis of DNA.

    Non-megaloblastic Anemia - Alcoholism

    • MCV: 100-110 fL
    • Diagnosis: Michigan Alcohol Screening Test, γ-glutamyltransferase level

    Non-megaloblastic Anemia - Hypothyroidism

    • Thyroid hormone stimulates the production of erythropoietin, impacting hematopoiesis
    • Reduction of thyroid hormone causes anemia

    Non-megaloblastic Anemia - Drugs

    • Interference with the absorption, plasma transport, or delivery of folate or vitamin B12
    • Example drugs: Hydroxyurea, Methotrexate, Zidovudine.

    Differential Diagnosis

    • High MCV:

      • B12 deficiency (serum B12 < 200 pg/mL)
      • Folate deficiency (serum folate < 2 ng/mL)
      • B12 (200-300), check methylmalonic acid (relationship to B12).
      • Elevated homocysteine (conversion to methionine reliant on B12- low levels associated with high homocysteine)

    • Check reticulocytes, elevated= hemolysis/blood loss; low = alcoholism, hypothyroidism, MDS, liver disease

    • Check Lactate dehydrogenase, Indirect bilirubin, Haptoglobin (for hemolysis suspicion)

    Calculating MCV

    • MCV calculation formula: (Hct X 10)/RBC
    • Different MCV values result in different diagnoses

    Calculating Red Cell Indices

    • Formulae and examples given for calculating red cell indices (MCV, MCH, MCHC) using hematocrit, hemoglobin and red cell values.
    • Corresponding diagnoses are provided.

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    Related Documents

    Macrocytic Anemia PDF

    Description

    Test your knowledge on vitamin B12 deficiency anemia and its implications. This quiz covers the functions of vitamin B12, causes of anemia, and diagnostic criteria. Ideal for medical students and health professionals seeking to deepen their understanding of macrocytic anemias.

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