From the Guidelines
Neutrophil segments and absolute neutrophils are two distinct measures of neutrophil count, with absolute neutrophils being a more comprehensive and clinically relevant measure of infection risk and immune function. The key difference between neutrophil segments and absolute neutrophils lies in their measurement and clinical implications. Neutrophil segments, also known as segmented neutrophils or "segs", refer to mature neutrophils with a segmented nucleus, representing the final stage of neutrophil development, and are typically reported as a percentage of the total white blood cell count on a differential 1. In contrast, absolute neutrophils (or absolute neutrophil count, ANC) represent the total number of all neutrophils in a given volume of blood, including both mature segmented neutrophils and immature band neutrophils, providing a more comprehensive measure of neutrophil presence in the bloodstream. Some key points to consider include:
- The ANC is a more useful measure for assessing infection risk and immune function, particularly in patients with HIV disease or undergoing chemotherapy, where a depressed ANC is associated with an increased risk for bacterial infections, including pneumonia 1.
- The relationship between these measurements is straightforward: the ANC can be calculated by multiplying the total white blood cell count by the percentage of neutrophils (both segments and bands) in the differential.
- Clinically, an ANC below 500 cells/μL indicates severe neutropenia and high infection risk, and healthcare providers may consider taking steps to reverse neutropenia, either by stopping myelosuppressive drugs or by administering granulocyte-colony stimulating factor (G-CSF) 1.
From the Research
Neutrophil Segments and Absolute Neutrophils
- Neutrophil segments refer to the percentage of neutrophils that are segmented, or mature, in a blood sample.
- Absolute neutrophils, on the other hand, refer to the total number of neutrophils per unit of blood, usually measured in cells per microliter (µL) or cells per liter (L) 2, 3.
Key Differences
- The main difference between neutrophil segments and absolute neutrophils is that neutrophil segments measure the proportion of mature neutrophils, while absolute neutrophils measure the total number of neutrophils.
- A low absolute neutrophil count (ANC) can indicate neutropenia, a condition characterized by a decreased number of neutrophils in the blood, which can increase the risk of infection 4, 5.
Clinical Significance
- Monitoring absolute neutrophil counts is crucial in patients receiving chemotherapy, as it can help predict the risk of febrile neutropenia and guide treatment decisions 5.
- Granulocyte colony-stimulating factor (G-CSF) is often used to stimulate the production of neutrophils in patients with neutropenia, and its effectiveness can be measured by monitoring absolute neutrophil counts 2, 6.