There are many times when a physician will request what is known as a complete blood count (often abbreviated as CBC). This may be performed to screen for a specific disease, to detect the presence of certain chemicals or to monitor a latent issue such as a chronic inflammation.
A CBC is also ordered to determine the health of the immune system of a patient. In such a case, a number of discrete values will be calculated. An analysis of these values may help to guide treatments or to discover if another underlying illness is present.
One of these examinations involves white blood cells and specifically, a type of cell known as a neutrophil (sometimes referred to as neutrocytes). This is often referred to as the absolute neutrophil count (ANC) and various techniques are employed in order to ascertain an accurate reading.
A neutrophil is the most common type of white blood cell. They are produced by the stem cells found within human bone marrow. They perform various functions including (but not limited to) ingesting microorganisms, ameliorating the effects of an inflammation and combating microbes contained within the blood stream.
Now that we have developed a basic understanding of the process of these white blood cells, it is important to appreciate how "segs" and "bands" function as well as their values within a healthy patient.
The values of both types will often be used to determine whether or not a patient may be suffering from a condition known as neutropenia. As may already be surmised, neutropenia is characterized by a very low count of neutrophils within the total white blood cell count (WBC). This is why appreciating their values is quite important.
Please note that clinicians will not directly measure the absolute neutrophil count. It is instead a product of the total WBC (white blood cell count) and the aggregate percentages of both the neutrophil segments and bands. In simpler terms, the normal values associated with the combination of these two types falls between 1.5 to 8. Most physicians feel that a count of 1.5 is normal and does not require treatment. Counts between 500 and 1,500 is "safe" and will only require monitoring (1).
Expressed in another manner that may be simpler to understand, this equates to 1,500 to 8,000 neutrophils per cubic milliliter of blood. A cubic milliliter of blood is also known as a microliter (μl).
Total ANC values of below 500 indicate a severe risk of infection. In the same respect, very high values could signal the presence of an autoimmune disease. The analysis of the total neutrophil count is often referred to as a "differential" within clinical settings, as it is one of a number of tests which comprise a complete blood count.
Please note that the values mentioned above may differ slightly depending upon age and gender. Pregnant women will likewise exhibit moderately higher levels although in the majority of cases, this is completely normal and will warrant no clinical action (3).
In relation to the total count of neutrophil bands and segments, it is critical to mention that those with fewer than 500 have been associated with mortality rates as high as 70 percent within 24 hours (4).
Although variations in the normal range of segments and bands is normally temporary, those with genetic predispositions may require intervention techniques such as hematopoietic growth factors and specific recombinant preparations including granulocyte colony-stimulating factors.