Rapid Review: Megaloblastic Anemia

Reviewed February 2024

Macrocytic Anemia

• Includes megaloblastic anemia, alcohol or liver disease, nutrient deficiency, reticulocytosis, drug-induced macrocytosis
• Sx: fatigue, weakness
• PE: pallor, glossitis
• Labs: MCV > 100 fL and hypersegmented neutrophils
• Most commonly caused by vitamin B12 (cobalamin), folate deficiency, direct ethanol toxicity
• Only vitamin B12 deficiency results in neurological symptoms

Sample question:

An 84-year-old woman presents to the clinic with fatigue and weight loss for several months. She reports eating very little in her daily meals. A CBC shows a hemoglobin of 9.2 g/dL and mean corpuscular volume of 124 fL. Which one of the following findings would be expected on a peripheral blood smear?