Comparison of Megaloblastic and Non-Megaloblastic Macrocytic Anemia

Definition and Classification of Macrocytic Anemia

Macrocytic anemia is characterized by the presence of enlarged red blood cells (macrocytes) with a mean corpuscular volume (MCV) above 100 fL. It can be classified into two types: megaloblastic and non-megaloblastic anemia.

Megaloblastic Macrocytic Anemia

Causes

• Vitamin B12 deficiency
• Folic acid deficiency
• Drug-induced (e.g., methotrexate, hydroxyurea)

Pathophysiology

Megaloblastic anemia arises due to impaired DNA synthesis, leading to nuclear-cytoplasmic asynchrony and large immature RBCs.

Clinical Features

• Pallor and fatigue
• Neurological manifestations (in B12 deficiency)
• Glossitis

Diagnosis and Treatment

Diagnosis is confirmed with serum B12 and folate levels, peripheral smear findings, and bone marrow examination. Treatment includes vitamin supplementation.

Non-Megaloblastic Macrocytic Anemia

Causes

• Alcoholism
• Liver disease
• Hypothyroidism

Pathophysiology

Unlike megaloblastic anemia, non-megaloblastic macrocytic anemia does not result from defective DNA synthesis. Instead, conditions such as alcoholism or liver dysfunction alter RBC membrane integrity and maturation.

Clinical Features

• Jaundice (liver disease-related)
• Neuropathy (alcohol-induced)
• Fatigue

Diagnosis and Treatment

Diagnostic tests include liver function tests, thyroid function tests, and peripheral blood smear analysis. Treatment focuses on managing the underlying cause.