Neutrophils are a type of white blood cell. When there are too many of them circulating in the blood, a doctor may diagnose a person with neutrophilia. Neutrophilia is a fairly common symptom of many conditions and presents in almost all infections. It's possible for a person to have elevated neutrophils without knowing or ever being tested. However, if testing reveals elevated neutrophils, it's important to discover the underlying cause in case the patient requires medical intervention.
Neutrophils are an essential part of the immune system and make up between 40 and 70 percent of white blood cells in mammals. Humans make around 100 billion of these cells each day because they only live for eight hours. Neutrophils are unique among white blood cells because they can move through the walls of veins into cells.
Because neutrophils can cross veins into cells, they can go directly to the source of infection or inflammation. This means they are on the front line of defense against any organisms that invade the body. Neutrophils eat the invading infectious cells. Once the infection is inside the neutrophil, an enzyme destroys it. Neutrophils also activate other cells in the immune system, helping eradicate infections. Neutrophils are the primary component of pus.
Neutrophilia is a high number of neutrophils in the blood compared to a healthy individual of the same age, sex, race, and physiological status. This number varies considerably between demographics; people of African and Middle Eastern descent have lower average counts, so their "normal" begins at a lower number. The opposite of neutrophilia is neutropenia, which is a low level of neutrophils.
The absolute neutrophil count (ANC) is generally part of a complete blood count (CBC) with differential. A CBC measures the cells in the blood. ANCs are generally ordered by doctors to screen for or help diagnose conditions and monitor the health of people with existing conditions or those undergoing chemotherapy. To test for neutrophils, doctors withdraw blood from the vein and send it to a lab for evaluation. Those with abnormal ANCs often undergo repeat testing to monitor changes.
High neutrophil counts can be a normal part of various physiological processes. Both pregnancy and menstruation can lead to high neutrophil counts in women. Excessive exercise and stress can also cause neutrophilia. Certain drugs can lead to an elevated neutrophil count, including cigarettes and steroids. People who have recently had surgery also tend to have high counts. A complete health history can help doctors eliminate some causes of neutrophilia.
External factors cause reactive neutrophilia. The most common cause is an infection, when the body creates extra neutrophils to combat invading organisms. Neutrophils fight bacterial infections as well as some viral, fungal, and parasitic infections. If you're sick, your neutrophil count is likely raised. The high neutrophil count helps stave off conditions including tonsillitis, appendicitis, and polio.
Non-infectious conditions include burns, heart attacks, asthma, and acute gout. People who have recently undergone surgery can also develop inflammation. Neutrophil numbers increase in reaction to adrenocortical hormones that also increase during such situations. Some neutrophilia comes with increased proportions of younger neutrophils. This "left shift" neutrophilia commonly affects people with severe burns and requires close monitoring, as it can become toxic.
Neutrophilia can be a sign of a serious condition such as lead or mercury poisoning. It may indicate an acute hemorrhage in a joint or intracranial cavity. Neutrophilia is a sign of preeclampsia, diabetic ketoacidosis; sudden kidney failure can also cause neutrophilia. All of these conditions require medical intervention.
A high neutrophil count can be a sign of malignancy in the blood. In particular, chronic myeloid leukemia, a cancer of the white blood cells, is characterized by a proliferation of neutrophils and other types. Neutrophilia can also indicate other blood conditions such as anemia and polycythemia. Some people may have hereditary neutrophilia.
There is no specific treatment for neutrophilia -- doctors will identify and treat the underlying cause. Some infections just need the neutrophils to do their job, and the cell count will return to normal once the infection is gone. Other conditions require intervention. Bacterial infections may call for antibiotics, severe burns need hospitalization, and people with cancer may need to undergo chemotherapy.
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