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Megaloblastic anemia

Updated: Feb 23

  • Megaloblastic anemia is a type of anemia characterized by the presence of large, abnormal RBCs (megaloblasts) in the bone marrow and peripheral blood.

  • It is primarily caused by deficiencies in vitamin B12 or folic acid, which are essential for DNA synthesis.

Causes of Megaloblastic anemia

Vitamin B12 Deficiency

  1. Dietary Deficiency: Insufficient intake of animal products (common in vegans).

  2. Malabsorption: Pernicious anemia (autoimmune destruction of stomach cells producing intrinsic factor), surgical removal of parts of the stomach or intestines, gastrointestinal diseases (e.g., Crohn's disease).

  3. Other Causes: Chronic alcoholism, certain medications (e.g., metformin, proton pump inhibitors).

Folic Acid Deficiency

  1. Dietary Deficiency: Poor intake of folate-rich foods (leafy greens, fruits, nuts, beans).

  2. Increased Demand: Pregnancy, lactation, rapid cell turnover (hemolytic anemia, cancer).

  3. Malabsorption: Conditions like celiac disease or surgical removal of parts of the intestines.

  4. Other Causes: Chronic alcoholism, certain medications (e.g., methotrexate, anticonvulsants).

Pathophysiology

Pathophysiology of Megaloblastic Anemia
Pathophysiology of Megaloblastic Anemia

  • Deficiencies in vitamin B12 or folic acid disrupt DNA synthesis, leading to the production of large, immature RBCs (megaloblasts).

  • These abnormal cells have impaired ability to divide and mature properly, resulting in anemia and ineffective hematopoiesis.

Symptoms

Symptoms of megaloblastic anemia can include:

  1. Fatigue and weakness

  2. Shortness of breath

  3. Pale or jaundiced skin

  4. Glossitis (inflamed, sore tongue)

  5. Neurological symptoms (specific to vitamin B12 deficiency): Numbness and tingling in hands and feet, balance problems, cognitive disturbances.

  6. Gastrointestinal symptoms: Loss of appetite, weight loss, diarrhea.

Diagnosis

Diagnosis typically involves:

  1. Complete Blood Count (CBC): Low hemoglobin, high mean corpuscular volume (MCV).

  2. Serum Vitamin B12 and Folate Levels: Low levels indicate deficiency.

  3. Peripheral Blood Smear: Presence of large, oval-shaped RBCs (macrocytes) and hypersegmented neutrophils.

  4. Bone Marrow Examination: Megaloblastic changes in bone marrow cells.

  5. Methylmalonic Acid and Homocysteine Levels: Elevated in vitamin B12 deficiency.

Treatment

Vitamin B12 Deficiency

  1. Dietary Changes: Increase intake of vitamin B12-rich foods (meat, fish, dairy, fortified cereals).

  2. Vitamin B12 Supplements: Oral supplements or intramuscular injections for those with absorption issues.

  3. Treat Underlying Causes: Address gastrointestinal conditions or dietary deficiencies.

Folic Acid Deficiency

  1. Dietary Changes: Increase intake of folate-rich foods (leafy greens, fruits, nuts, beans).

  2. Folic Acid Supplements: Oral supplementation.

  3. Treat Underlying Causes: Address malabsorption issues or increased demand conditions.


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