Eosinophils may not be a term you hear often, but these unique white blood cells play a vital role in your body’s immune system. Whether you’ve had blood work done or you’re dealing with allergies, asthma, or an unexplained infection, you might come across the term eosinophils. Understanding what eosinophils do, and what it means, can give you important insights into your health.
In this article, we’ll explain what eosinophils are, the significance of low or high eosinophil counts, and the potential causes behind these fluctuations.
What Are Eosinophils?
Eosinophils are a type of white blood cell that is part of your immune system. Their primary role is to help your body fight off infections, particularly those caused by parasites. Eosinophils also play a key role in allergic reactions and inflammatory processes.
When you think of the immune system, you might imagine white blood cells fighting off bacteria or viruses. Eosinophils, however, are more specialized. They’re particularly effective at dealing with multicellular parasites (like worms) and also respond to allergies, asthma, and certain autoimmune conditions.
Eosinophils are produced in your bone marrow and then released into the bloodstream. They normally make up about 1-4% of your white blood cells, so under normal conditions, their count is relatively low compared to other white blood cells.
However, when your body senses an invader or allergen, eosinophils jump into action and their numbers can rise significantly.
What Does It Mean to Have a Low or High Eosinophil Count?
Your eosinophil count can be measured through a blood test, specifically a complete blood count (CBC) with a differential that checks the various types of white blood cells. Depending on whether your eosinophil count is low or high, it could signal different health conditions or reactions in your body.
Normal Eosinophil Count
A normal eosinophil count typically falls between 0.0 to 0.5 x 10^9/L (0 to 500 cells per microliter of blood). For most people, the number of eosinophils fluctuates slightly based on factors like time of day (eosinophil levels are often higher in the evening) or individual health conditions.
High Eosinophil Count (Eosinophilia)
When your eosinophil count exceeds normal levels, it’s referred to as eosinophilia. This can be classified into:
- Mild eosinophilia: 500 to 1,500 cells per microliter
- Moderate eosinophilia: 1,500 to 5,000 cells per microliter
- Severe eosinophilia: More than 5,000 cells per microliter
Eosinophilia can be a response to a wide variety of conditions, from allergies and infections to more serious diseases like certain cancers.
Low Eosinophil Count (Eosinopenia)
A low eosinophil count, or eosinopenia, is when the level of eosinophils in the blood is lower than normal. Eosinopenia is less common than eosinophilia and is usually associated with conditions that suppress the immune system.
Causes of High Eosinophil Count (Eosinophilia)
If your eosinophil count is elevated, it’s important to understand the underlying causes. While high eosinophil levels can be a response to infections or allergic reactions, persistently high counts may indicate more serious health conditions. Below are some common and more complex causes of eosinophilia:
1. Allergies and Asthma
Eosinophils are closely associated with allergic reactions. When you’re exposed to an allergen (such as pollen, dust mites, or pet dander), eosinophils rush to the scene, releasing chemicals that contribute to inflammation. This is part of why allergies cause symptoms like swelling, congestion, or itchy skin.
People with asthma often have higher eosinophil counts, especially during asthma attacks. There is a specific condition called eosinophilic asthma, where eosinophils play a major role in causing airway inflammation.
Plus, If you suffer from seasonal allergies, your body may produce more eosinophils as part of its defense mechanism. While they help combat allergens, they also contribute to the uncomfortable symptoms.
2. Parasitic Infections
One of the primary functions of eosinophils is to fight off parasitic infections. If your body is battling a parasite, such as intestinal worms or schistosomiasis, eosinophil levels can rise significantly.
Common parasites: Roundworms, hookworms, and trichinosis are just a few examples of parasitic infections that can elevate eosinophil counts.
If someone travels to a region where parasitic infections are common and contracts one, their eosinophil count might spike as their body fights the infection.
3. Autoimmune Diseases
In some autoimmune diseases, the immune system mistakenly attacks healthy tissues, and eosinophils can be part of this misguided attack.
- Eosinophilic esophagitis: This is a condition where eosinophils build up in the lining of the esophagus, leading to inflammation and difficulty swallowing.
- Churg-Strauss syndrome: Also known as eosinophilic granulomatosis with polyangiitis, this rare autoimmune condition involves high eosinophil counts and can cause damage to the lungs, skin, and other organs.
4. Skin Disorders
Certain skin conditions can also elevate eosinophil levels as part of the body’s inflammatory response.
- Eczema: A chronic skin condition that causes itchy, inflamed patches, eczema is often linked with elevated eosinophils.
- Psoriasis: While not always associated with high eosinophils, flare-ups of this skin condition can sometimes lead to increased levels.
5. Inflammatory Disorders
Chronic inflammatory diseases can result in long-term elevated eosinophil levels. One such example is inflammatory bowel disease (IBD), where eosinophils play a role in gut inflammation.
Ulcerative colitis and Crohn’s disease: These conditions, which cause chronic inflammation in the digestive tract, often show elevated eosinophil counts during flare-ups.
6. Certain Cancers
In some cases, eosinophilia can be a sign of blood cancers, such as leukemia or Hodgkin’s lymphoma. These cancers affect the production and regulation of white blood cells, including eosinophils.
Chronic eosinophilic leukemia: This rare type of cancer specifically involves an overproduction of eosinophils in the bone marrow.
7. Medications and Drug Reactions
Certain medications, such as antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), and antidepressants, can trigger an increase in eosinophils as part of an allergic reaction or side effect.
Drug-induced eosinophilia: In some cases, a medication can cause an allergic-like reaction that leads to high eosinophil counts.
Causes of Low Eosinophil Count (Eosinopenia)
While eosinopenia is less common and often less concerning than eosinophilia, there are still reasons why a person might have low eosinophil levels. These include conditions or treatments that suppress the immune system:
1. Stress and Cortisol
High levels of stress can lead to reduced eosinophil counts. When your body is under stress, it produces cortisol, a hormone that can suppress the immune system, including the production of eosinophils.
Corticosteroid medications: Corticosteroids, which mimic the effects of cortisol, are commonly used to treat inflammatory conditions, allergies, and asthma. While effective, these drugs can reduce eosinophil counts.
2. Acute Infections
During the initial phase of an acute infection, such as a viral or bacterial infection, your eosinophil count may temporarily drop. This is because the immune system directs its resources toward fighting off the infection, which can reduce eosinophil production in the short term.
Sepsis: In severe infections like sepsis, the immune system is overwhelmed, and eosinophil levels may plummet as the body struggles to respond to the infection.
3. Cushing’s Syndrome
Cushing’s syndrome is a condition characterized by prolonged exposure to high levels of cortisol. Since cortisol suppresses immune function, people with this syndrome often have lower eosinophil counts.
4. Autoimmune Disorders
Some autoimmune disorders, such as systemic lupus erythematosus (SLE), can cause eosinopenia, as these conditions may affect the body’s ability to produce normal levels of white blood cells, including eosinophils.
Symptoms of High Eosinophil Count
- Allergic reactions: sneezing, runny nose, itchy eyes, rashes
- Asthma: coughing, wheezing, shortness of breath
- Skin rashes or hives
- Abdominal pain or digestive issues (linked to eosinophilic esophagitis or IBD)
- Fatigue or weakness (especially in autoimmune conditions)
Symptoms of Low Eosinophil Count
Low eosinophil counts usually don’t cause direct symptoms. However, if eosinopenia is due to stress or corticosteroid use, you might notice:
- Increased susceptibility to infections
- Fatigue or feeling run down
How Are Eosinophil Counts Measured?
Eosinophil counts are typically measured during a complete blood count (CBC) test with a differential, which looks at the proportions of different white blood cells in your blood. If your doctor suspects an issue with your immune system or is investigating symptoms like allergies or unexplained infections, they may specifically check your eosinophil count.
What to Expect from a CBC Test
- A simple blood draw is taken, often from a vein in your arm.
- The sample is sent to a lab, where it’s analyzed for various blood components, including eosinophils.
- Your doctor will review the results to determine if your eosinophil count is within the normal range or if further investigation is needed.
Treating Abnormal Eosinophil Counts
Treatment for abnormal eosinophil counts depends on the underlying cause. Here’s a general overview of treatment options based on whether your eosinophil count is too high or too low:
For High Eosinophil Count (Eosinophilia)
- Treating allergies: Antihistamines or corticosteroids may be prescribed to manage allergic reactions or asthma.
- Addressing infections: If a parasitic infection is to blame, medications to eliminate the parasites will help reduce eosinophil levels.
- Managing autoimmune conditions: Autoimmune diseases often require long-term management with immunosuppressants or corticosteroids.
- Cancer treatment: If eosinophilia is due to cancer, chemotherapy or targeted cancer therapies may be necessary.
For Low Eosinophil Count (Eosinopenia)
- Addressing stress: Managing stress through relaxation techniques, exercise, and therapy can help normalize cortisol levels and support immune function.
- Corticosteroid management: If corticosteroids are causing low eosinophils, your doctor may adjust the dosage or recommend alternative treatments.
When to See a Doctor?
While eosinophil levels can fluctuate for many reasons, it’s important to see a doctor if you experience persistent symptoms, such as:
- Chronic or severe allergic reactions
- Asthma symptoms that don’t improve with treatment
- Unexplained rashes, abdominal pain, or digestive issues
- Frequent infections or illnesses that you can’t seem to shake
A healthcare provider can order the necessary tests, review your medical history, and determine the best course of action.
Conclusion
Eosinophils may be small, but they play a big role in keeping your body’s immune system functioning properly. Whether you’re dealing with allergies, autoimmune conditions, or infections, understanding how eosinophils work and what your eosinophil count means can help you stay informed about your health.
If your eosinophil count is abnormal, don’t panic. Many factors can influence these numbers, and your doctor can guide you toward the right treatment plan. By staying proactive about your health, you can help ensure your immune system continues to protect you effectively.
