Eosinophil Count

A type of white blood cell associated with allergies and parasitic infections.

What it is

Eosinophils are a type of white blood cell, which are part of your immune system. They are one of several types of 'granulocytes', a group of white blood cells that contain tiny sacs (granules) filled with enzymes and other substances. Eosinophils are named after the way they stain pinkish-orange under a microscope, due to a particular dye called eosin.

Your body produces eosinophils in the bone marrow and they circulate in your bloodstream. They can also travel into tissues throughout your body, particularly in areas like your lungs, skin, and digestive tract. Their main job is to help your body fight off certain types of infections, especially those caused by parasites. They also play a role in your body's allergic responses.

An eosinophil count is a measurement of how many of these specific white blood cells are present in a sample of your blood. It's usually reported as part of a Full Blood Count (FBC) or Complete Blood Count (CBC) test. The result is typically given in units of 10^9 cells per litre (10^9/l) of blood. In the UK, a typical reference range for eosinophils is between 0.04 and 0.4 x 10^9/l.

Why it matters

The number of eosinophils in your blood can provide valuable clues about what might be happening in your body. While a normal count suggests your immune system is functioning as expected in relation to these cells, an unusually high or low count can sometimes indicate an underlying issue.

Eosinophils are particularly known for their involvement in two main areas:

• Allergic reactions: When your body encounters an allergen (like pollen, dust mites, or certain foods), eosinophils can be activated. They release substances that contribute to the inflammation and symptoms associated with allergies, such as asthma, eczema, hay fever, and food allergies.
• Parasitic infections: Eosinophils are a key defence against larger parasites that can infect the body, such as certain types of worms. They can attach to the surface of these parasites and release toxic substances to damage and kill them.

Therefore, monitoring eosinophil levels can help healthcare professionals investigate symptoms related to allergies or potential parasitic infections, and to assess the effectiveness of treatments for these conditions.

What can cause it to be high or low

An elevated eosinophil count (also known as eosinophilia) is more commonly identified than a low count. Several factors can lead to higher than normal levels:

• Allergic conditions: This is a very common cause. Conditions like asthma, allergic rhinitis (hay fever), atopic dermatitis (eczema), and food allergies are frequently associated with increased eosinophils.
• Parasitic infections: Infections with certain types of parasites, particularly those that enter the bloodstream or tissues, can significantly raise eosinophil counts.
• Certain skin conditions: Some non-allergic skin disorders can also be linked to eosinophilia.
• Drug reactions: Some medications can trigger an increase in eosinophils as a side effect or an allergic-type reaction.
• Other inflammatory conditions: Less commonly, other inflammatory diseases or autoimmune conditions might be associated with higher eosinophil levels.
• Certain cancers: In rare instances, some types of cancer can lead to eosinophilia.

A low eosinophil count (hypereosinophilia) is less common and often less significant. It can sometimes be seen in:

• Certain acute infections: Particularly bacterial infections.
• Stress responses: The body's stress response can sometimes temporarily lower eosinophil counts.
• Cushing's syndrome: A condition where the body produces too much cortisol.
• Treatment with corticosteroids: Steroid medications can suppress eosinophil production.

It's important to remember that a single high or low reading doesn't automatically mean there's a serious problem. Your doctor will consider your eosinophil count alongside your symptoms, medical history, and other test results.

Lifestyle factors that may help

For individuals whose eosinophil count is elevated due to allergic conditions, certain lifestyle adjustments can be beneficial and are often discussed with healthcare professionals:

• Identifying and avoiding triggers: For allergies like hay fever or eczema, pinpointing and minimising exposure to known allergens (e.g., pollen, pet dander, certain foods) can be helpful.
• Maintaining a healthy diet: A balanced diet rich in fruits, vegetables, and whole grains supports overall immune function. Some people find that certain dietary changes can influence their allergic responses, and this is a topic that can be explored with a doctor or dietitian.
• Managing stress: Chronic stress can sometimes impact the immune system. Exploring stress-reduction techniques such as mindfulness, gentle exercise, or yoga might be considered.
• Regular physical activity: Moderate exercise can contribute to overall well-being and may help manage inflammatory conditions.
• Good hygiene practices: For preventing parasitic infections, maintaining good personal hygiene and ensuring food and water are safe are important measures.

These lifestyle factors are generally beneficial for health and may help in managing conditions associated with eosinophil levels.

Questions to discuss with your GP

If your eosinophil count has been noted as high or low, or if you have symptoms you're concerned about, it's always best to have a conversation with your GP. Here are some questions you might consider discussing:

• What does my specific eosinophil count mean in the context of my overall health and any symptoms I'm experiencing?
• Could my eosinophil level be related to allergies, and if so, what further tests might be helpful to identify any specific triggers?
• Are there any lifestyle changes or dietary considerations that might be relevant for me to discuss, given my eosinophil result?
• What are the potential causes for an elevated or reduced eosinophil count, and how do we determine the most likely cause in my case?
• Are there any other tests or investigations you would recommend based on this result?
• If treatment is recommended, what are the potential benefits and side effects I should be aware of?