Eosinophils are a type of white blood cell, also known as leukocytes, which are a fundamental component of the body’s immune system. These cells originate in the bone marrow and then circulate in the bloodstream before residing in various tissues throughout the body, including the gastrointestinal tract, lungs, and skin. Eosinophils play a significant role in defending the body against foreign invaders, particularly multicellular parasites like worms. Beyond combating parasitic infections, they are also involved in the body’s response to allergic reactions, contributing to inflammatory processes associated with conditions such as asthma and eczema.
Measuring Eosinophils and Normal Ranges
Eosinophil counts are typically determined as part of a routine Complete Blood Count (CBC) with differential, a common blood test. This test measures the absolute number of eosinophils per microliter of blood, as well as their percentage relative to the total white blood cell count. For most adults, a normal eosinophil count generally ranges from 0 to 500 cells per microliter of blood. Alternatively, eosinophils typically constitute less than 5% of the total white blood cells.
These normal ranges can vary slightly between different laboratories due to variations in testing equipment and methodologies. A count within this established range indicates a balanced immune system, where eosinophils are present in appropriate numbers to perform their functions. Consistent levels within this range suggest that the body’s defense mechanisms are operating effectively.
When Eosinophil Levels Are High
An elevated eosinophil count, a condition termed eosinophilia, indicates an increased immune response. Counts exceeding 500 cells per microliter are considered high. The most common causes for these elevated levels often involve allergic reactions, such as seasonal allergies, asthma, and eczema, where eosinophils contribute to the inflammation.
Parasitic infections, particularly those caused by worms that invade body tissues, are another frequent cause of eosinophilia, as these cells are specifically tasked with fighting such pathogens. Certain autoimmune conditions, where the immune system mistakenly attacks the body’s own tissues, can also lead to increased eosinophil levels. Furthermore, some medications, including certain antibiotics, tranquilizers, and even some non-steroidal anti-inflammatory drugs (NSAIDs), have been known to cause an increase in eosinophil counts as a side effect. Leukemia and other blood disorders can also result in abnormally high eosinophil counts, reflecting an overproduction of these cells in the bone marrow.
When Eosinophil Levels Are Low
A lower-than-normal eosinophil count, known as eosinopenia, means there are fewer of these white blood cells circulating in the bloodstream. While less common than elevated levels, eosinopenia can occur due to various factors. Acute stress can lead to a temporary decrease in eosinophil.
Certain infections, particularly severe bacterial infections like sepsis, may also cause eosinophil to drop. Corticosteroids, whether prescribed or due to conditions like Cushing’s syndrome, can significantly reduce eosinophil counts. This reduction occurs because corticosteroids can induce programmed cell death and inhibit their movement into the bloodstream. Often, a single low eosinophil count might not be a significant health concern, as other white blood cells can compensate.
What Abnormal Results Mean for You
An abnormal eosinophil count, whether high or low, is an indicator that warrants further attention rather than a definitive diagnosis on its own. These results suggest that your immune system may be responding to an underlying condition. Various factors, including temporary stress or medication use, can impact these levels.
If your eosinophil count falls outside the typical range, consult a healthcare professional. They will interpret your results in the context of your overall health, medical history, and any symptoms. This evaluation allows for proper diagnosis and the determination of any necessary follow-up actions or treatments, emphasizing professional medical guidance rather than self-diagnosis or self-treatment.