Anisocytosis

Anisocytosis

A peripheral blood smear showing various sizes of red blood cells. Image courtesy of Wiki Commons.

Anisocytosis refers to the presence of red blood cells of unequal sizes in a blood sample. The term derives from the Greek words "aniso" (unequal) and "cyte" (cell). It is a common finding in various hematological disorders and is often used as a diagnostic clue in clinical pathology.

Overview

Red blood cells (RBCs) typically have a uniform size under normal physiological conditions. However, certain medical conditions can lead to the production or transformation of RBCs into irregular sizes. Anisocytosis is not a disease in itself but rather an indicator of an underlying hematological disorder.

Measurement

The determination of the number of anisocytes present in a sample is typically achieved through:

• Peripheral Blood Smear: A microscopic examination of a blood smear can visually assess the variation in RBC size.
• Red Cell Distribution Width (RDW): An automated measurement done on most blood analyzers that quantitatively determines the variability in red blood cell size.

Causes

Anisocytosis can result from various conditions including:

• Iron-deficiency anemia: Often associated with smaller than normal RBCs.
• Megaloblastic anemia: Linked with larger than normal RBCs due to impaired DNA synthesis.
• Sickle cell anemia: This condition produces irregularly shaped and sized RBCs.
• Reticulocytosis: Elevated numbers of reticulocytes (immature RBCs) which are larger than mature RBCs.
• Hemolytic anemias: Destruction of RBCs can result in the production of various sizes of red blood cells.
• Liver diseases: Can lead to anisocytosis due to altered lipid metabolism affecting RBC membranes.

Clinical Implications

The presence of anisocytosis is a valuable diagnostic hint. By determining the degree and type of anisocytosis (microcytosis, macrocytosis, or a combination), clinicians can narrow down potential underlying disorders. This can guide further diagnostic tests and potential therapies.

Treatment

Management of anisocytosis revolves around addressing its root cause. For instance:

• Treating iron-deficiency anemia with iron supplements or dietary changes.
• Addressing vitamin B12 or folate deficiency in cases of megaloblastic anemia.
• Blood transfusions or specific treatments for conditions like sickle cell anemia.

Conclusion

Anisocytosis serves as a key hematological marker. Recognizing its presence and understanding the potential underlying causes are vital for proper diagnosis and management of the associated medical conditions.

References

Anisocytosis Resources
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