Megaloblastic Anemia

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Questions and Answers

What distinguishes megaloblastic anemia from other types of anemia?

Presence of abnormally sized developing red cells (correct)

Presence of leukocytes in the bloodstream

Presence of small red blood cells

Presence of iron deficiency

Which form of Vitamin B12 is primarily found in the mitochondria?

Inactive cobalamin

Ado (2-deoxyadenosyl) form (correct)

Methyl cobalamin

Hydroxocobalamin

Which of the following is NOT considered a cause of megaloblastic anemia?

Folate deficiency

Iron deficiency (correct)

Drugs interfering with DNA synthesis

Vitamin B12 deficiency

What is the role of intrinsic factor in Vitamin B12 absorption?

It facilitates active absorption of Vitamin B12 Signup and view all the answers

How long can the body store Vitamin B12 without dietary intake before deficiency occurs?

3-4 years Signup and view all the answers

Which process primarily leads to macrocytic anemia in megaloblastic anemia?

Ineffective erythropoiesis Signup and view all the answers

What is the daily requirement of Vitamin B12 for the human body?

1-3 μg Signup and view all the answers

What effect does nitrous oxide inhalation have regarding megaloblastic anemia?

It influences DNA synthesis Signup and view all the answers

What is the main dietary cause of cobalamin deficiency in individuals following a specific diet?

Consumption of legumes Signup and view all the answers

Which condition is typically associated with malabsorption of cobalamin?

Crohn’s disease Signup and view all the answers

Which neurologic finding is NOT associated with cobalamin deficiency?

Severe headache Signup and view all the answers

What is the daily folate requirement for pregnant women?

400μg Signup and view all the answers

Which of the following statements about folate absorption is correct?

Alcohol can interfere with folate release from the liver Signup and view all the answers

What is a common clinical feature associated with megaloblastic anemia?

Macrocytosis Signup and view all the answers

Which of the following conditions may result from maternal folate deficiency during pregnancy?

Neural tube defects Signup and view all the answers

Which neurological condition is linked to vitamin B12 deficiency?

Alzheimer’s disease Signup and view all the answers

Study Notes

Overview of Megaloblastic Anemia

Characterized by abnormally large red blood cells in the bone marrow, indicating ineffective erythropoiesis.
Involves nuclear and cytoplasmic maturation dissociation, leading to macrocytic anemia.
Resulting from impaired DNA synthesis due to deficiencies in folate or Vitamin B12.

Etiology of Megaloblastic Anemia

Vitamin B12 (Cobalamin):
- Deficiency can occur due to malabsorption or abnormal metabolism.
- Forms of Vitamin B12 include:
  - Ado (2-deoxyadenosyl) - mitochondrial cofactor for Methyl Malonyl CoA Mutase.
  - Methyl cobalamin - cofactor for Methionine synthase.
  - Hydroxocobalamin - involved in related metabolic processes.
Folate (Folic Acid):
- Easily destroyed by cooking, particularly in large water quantities.
- Requires approximately 200-300 μg daily, with an increased demand during pregnancy (400 μg).
- Stored in the liver for about 3-4 months.

Absorption Mechanisms

Cobalamin Absorption:
- Active absorption requires Intrinsic Factor; passive absorption occurs at low rates.
- Absorption involves proteins such as intrinsic factor, haptocorrins, cubilin, and transcobalamin II.
- Cobalamin enters portal circulation approximately six hours post-ingestion.
Folate Absorption:
- Occurs in the upper small intestine.
- Transported by plasma proteins, with significant enterohepatic circulation.

Causes of Cobalamin Deficiency

Nutritional factors, particularly in vegans or those consuming legumes.
Malabsorption syndromes (e.g., gastrectomy, Crohn’s disease, pernicious anemia).
Abnormalities such as transcobalamin II deficiency.

Neurologic Implications of B12 Deficiency

Peripheral neuropathy manifests as a glove and stocking distribution of paresthesia and loss of ankle reflexes.
Spinal cord degeneration leads to diminished vibration and proprioception, as well as upper motor neuron signs.
Cerebral effects include dementia and optic atrophy, along with autonomic neuropathies.

Clinical Features Associated with Megaloblastic Anemia

Observed macrocytosis in epithelial surfaces.
Fertility issues in both genders.
Increased cardiovascular disease risk, including ischemic heart disease.
Links to malignancy, such as Acute Lymphoblastic Leukemia in children.
Neurologic conditions related to vitamin deficiencies include bilateral peripheral neuropathy and Alzheimer's disease.
Maternal complications include a higher risk of prematurity and neural tube defects in offspring.
Impaired brain development and intellectual deficits in affected children.

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Description

This quiz focuses on megaloblastic anemia, a condition characterized by the presence of abnormally large red blood cells in the bone marrow due to ineffective erythropoiesis. Test your understanding of the pathophysiology, clinical features, and implications of this hematological disorder.