What are bands in hematology tests?

In hematology, bands refer to immature neutrophils that have been released from the bone marrow before they have fully matured. They are characterized by their unique appearance under a microscope, with a nucleus that is indented or curved like a horseshoe or band. The cytoplasm of bands is also more basophilic (stains more deeply with basic dyes) compared to mature neutrophils.

Bands are released from the bone marrow as a response to increased demand for neutrophils, such as in cases of infection or inflammation. Their presence in the peripheral blood is considered a normal finding, as long as they make up only a small percentage of the total white blood cell count. However, an increased number of bands, known as bandemia, can be an indication of a medical condition that is causing neutrophil production to increase.

Various reasons can lead to bandemia, including:

Infection: Bacterial infections, especially severe or acute infections, can lead to a significant increase in the production and release of bands.

Bone marrow disorders: Conditions that affect the bone marrow, such as leukemia, myelodysplastic syndromes, and myeloproliferative disorders, can lead to disturbances in normal blood cell production, including increased release of immature neutrophils.

Hemolytic anemia: In cases of hemolytic anemia, where red blood cells are destroyed faster than they can be replaced, the bone marrow may respond by releasing immature neutrophils in an attempt to compensate for reduced oxygen-carrying capacity.

Certain medications: Some medications, particularly those that have a cytotoxic effect on bone marrow, can cause bandemia as a side effect.

Chronic inflammatory conditions: In cases of chronic inflammation, the persistent demand for neutrophils can lead to the release of immature forms, including bands.

When bandemia is identified in a blood test, further investigation may be necessary to determine the underlying cause. This may involve additional blood tests, imaging studies, and bone marrow evaluation to identify and address the underlying medical condition. In some cases, bandemia may also be monitored over time to assess the response to treatment and track the recovery of normal neutrophil production.