Macrocytic anemia

Macrocytic anemia
Specialty	Hematology

Macrocytic anemia is a condition and blood disorder characterized by the presence of predominantly larger-than-normal erythrocytes (red blood cells, or RBCs) accompanied by low numbers of RBC, which often carry an insufficient amount of hemoglobin. Due to the smaller ratio between the cell's surface area and its volume, the capacity of erythrocytes to properly carry and transport hemoglobin is diminished. This results in an insufficient availability of hemoglobin, hence the label of anemia.

The term macrocytosis refers to the expansion of the mean corpuscular volume of red blood cells. It has several possible causes, all of which produce slightly different red blood cell morphology. Detection methods include a complete blood count (CBC) and peripheral blood smears.

Neutrophils (white blood cells) also differ in their morphology in the megaloblastic variety of macrocytic anemia. A hypersegmentation of neutrophils refers to instances where there are six or more lobes present, resulting in a hypersegmented nucleus. This is a direct result of impaired DNA synthesis in the hematopoietic cells. In contrast, non-megaloblastic macrocytic anemia does not exhibit problematic DNA synthesis.

Possible causes include folic acid and/or Vitamin B₁₂ deficiencies, liver disease (including but not limited to results from chronic alcohol abuse), medications interfering with DNA synthesis (such as certain immunosuppressants like methotrexate and azathioprine), bone marrow disease, pregnancy, as well as autoimmune and endocrine conditions.

Treatment depends on severity and the underlying cause.