What is Eosinophilia?

Podcast Transcript

Raed Dweik, MD:

Hello, and welcome to the Respiratory Inspirations podcast. I'm Raed Dweik, chairman of the Respiratory Institute at the Cleveland Clinic. This podcast series of short, digestible episodes is intended for patients and families, and covers topics related to respiratory health and disease. My colleagues and I will be interviewing experts about timely and timeless topics, in the areas of pulmonary, clinical illness, sleep, infectious disease, and related disciplines.

We will share with you information that will help you take better care of yourself and your loved ones. I hope you enjoy today's episode. Hello, everyone, and welcome to this episode of Respiratory Inspirations. I'm Raed Dweik, the chairman of the Respiratory Institute, and my guest today is Dr. Fred Hsieh, who is the Director of the Allergy and Immunology Fellowship program, and the vice-chair of allergy and immunology at the Respiratory Institute at the Cleveland Clinic. Welcome, Fred.

Fred Hsieh, MD:

Thank you for having me today.

Raed Dweik, MD:

And our topic today is gonna focus on the eosinophil. It's a special blood cell that we're gonna talk about, it's mysterious for many doctors let alone patients. So, Dr. Hsieh is gonna break this down for us, and what does it mean when you have an abnormal eosinophil blood. So, let's start with that basic thing, you know? Fred, what is an eosinophil to start with?

Fred Hsieh, MD:

So, an eosinophil is a type of white blood cell. So, there are many types of white blood cells. They have various names, lymphocyte, monocyte, macrophage, eosinophil. They all have specific roles in the immune system, in terms of fighting infections, and participating in normal physiology and host defense, and the eosinophil is one of those cells.

It is usually present at low numbers in the peripheral blood, and interestingly, it's found in many organs of the body under normal situations. So, you normally find some low number of eosinophils all along the GI tract, and in various other organs of the body, including some organs of the body that you wouldn't expect to see inflammatory cells, like the uterus, for example, or in the breast tissue, or in the thymus. However, they are felt to have some normal physiologic roles at those sites, as well.

Raed Dweik, MD:

And usually, the way this comes to the attention of us, as physicians, and when you do a blood analysis, or blood count, routine blood count, that you have high count of eosinophils, and I suspect some of our patients and families will see it, you know, sometimes in communications with their doctors, or they check their blood tests and they see this number, like, flagged as high. So, what from a patient perspective, what should they think about when their eosinophilic count is high, or is flagged as high on a blood test?

Fred Hsieh, MD:

Now, that's an excellent question, and we certainly always get a lot of queries about it. So, the eosinophil count can be elevated, found incidentally, and associated with no specific disease. It's commonly associated with certain kinds of conditions. Most of those are allergies or allergic conditions.

Conditions like asthma, seasonal allergies, or allergic rhinitis, eczema, atopic dermatitis, and other types of skin conditions. The eosinophil is part of the normal human immune response. So, you could see an elevated eosinophil count if you have a certain kind of infection, not conventional bacterial or viral infections, but more uncommon infections, such as parasitic or fungal type infections, and then rarely is it associated with a primary blood condition, or blood disorder.

Like I said, the eosinophil is a white blood cell, and just like any other type of white blood cell, there can be abnormalities in the various types of white blood cells.

Raed Dweik, MD:

Okay, and you and I talked before this podcast about there's something to, like, high eosinophil count, but there's something called a different disease called hypereosinophilia. How is that different?

Fred Hsieh, MD:

So, eosinophilia simply refers to the fact that the eosinophil count is higher than the upper limit of normal in your laboratory, and so, any time you see a flag, that a patient might see a flag in the complete blood count with differential analysis, it just represents that the number is higher than the upper limit of normal.

Hypereosinophilia refers to an eosinophil count that's greater than a certain number, and the number happens to be 1,500. When you do the differential part of the complete blood count. Now, it's important to note that there can be significant diurnal, or daily variation, in the eosinophil count. If you check the blood- if you have your blood drawn early in the morning, the eosinophil count can be up to 40 percent lower than if you check your eosinophil count in the afternoon or evening, and that's attributed to the fact that your own adrenal gland is making steroids all the time, and the steroid surge by the adrenal gland typically occurs earlier in the morning.

And so, it's felt that that is related to this sort of daily variation in the peripheral blood eosinophil count. So, if you do see that the eosinophil count is greater than 1,500, it's not necessarily to panic (laughs) necessarily, but it is something that your provider, your physician, probably would be looking at to make sure there is nothing else going on.

Raed Dweik, MD:

So, actually, you mentioned the word panic. So, how urgent is this? Like, if I sometimes, you know, these days with electronic medical records, patients get their results even before they've heard from their doctor, which is sometimes, there's no context for that. So, how much should our patients panic if they see that number? Definitely, they should contact their provider, but anything else you can give them advice about?

Fred Hsieh, MD:

Well, I would say that it all depends upon why the blood count was checked in the first place. If you're coming in for your annual checkup with your physician, and they said, we're just gonna do routine laboratory studies, and they check the complete blood count, but you're not having any active symptoms, there may be nothing to worry about, and that might be something that can be worked up, you know, expeditiously, but over, you know, weeks and months, and not necessarily immediately.

However, if you're seeing your provider because you have a problem, like, you're having neurologic symptom, or you've got a diffuse rash, or something like that. Then, the context of the blood count makes a big difference or can make a big difference. So, the eosinophil, you know, you could be totally symptomatic, you could have some chronic symptoms that are not accelerating, or you could have acute disease, and I think that the condition that the provider is trying to evaluate you for would make a big difference as to whether or not this is something that they need to send you to a specialist right away, or work up over time, or just kind of follow.

Raed Dweik, MD:

So, depending on how sick you are, basically, it sounds like. If you're not very sick, and have no symptoms, I would just wait for the provider. If you're having significant symptoms, just call right away and try to figure something out.

Fred Hsieh, MD:

You've said it better than I did.

Raed Dweik, MD:

Yeah, no. Sounds good. So, what are the common causes? Let's say somebody is thinking about, why should I? What's the reason I'm having a high eosinophilic count? What are some of the things that can cause that?

Fred Hsieh, MD:

Well, so here in the developed world, if you're a patient here in the so-called developed world, then allergic conditions would be the most common. So, seasonal allergies, allergic rhinitis, asthma, atopic skin diseases, like eczema or atopic dermatitis. These would be the most common reasons why you might have an elevated eosinophil count and could indeed even have hypereosinophilia if you had some of these conditions, but yeah.

There would be a number of other things that your provider would think about. Is there a possibility that you have a rheumatologic, or autoimmune disease? Is it possible based on your travel history, or occupation, or other exposure that you might have some kind of parasitic infection? Is it possible based on some of your other symptoms that you have some endocrine problem? And then, there are rare conditions that are associated with some kind of malignancy, or cancer, and then there are, again, as we mentioned, some conditions where the eosinophil itself is abnormal, because it is a type of white blood cell.

So, it is a hematologic type problem, but I would want to emphasize that sort of the cancer, or malignancy related, eosinophil is very, very rare, and would not be the first thing that, you know, you would think about, in terms of evaluation of eosinophilia, and the same is true with the primary hematologic conditions involving quite elevated eosinophils, or hypereosinophilia.

Raed Dweik, MD:

So, if you had a patient, or a family member, or a patient, what kind of symptoms should alert you to when there's something going on, you know, beyond just an elevated eosinophilic count?

Fred Hsieh, MD:

That's not such an easy question to answer, in terms of, what are the symptoms of eosinophilia. I mean, you might have no symptoms whatsoever, like we mentioned, you know? A patient could have constitutional symptoms, sort of fatigue, night sweats and weight loss, and that kind of thing, or you could have distinct organ specific symptoms related to target organ involvement, or even target organ injury, such as a neurologic symptom, cardiovascular symptoms.

It's difficult to sort of, say, you know, what is the symptom of eosinophilia, or hypereosinophilia, because it could be nothing.

Raed Dweik, MD:

Yeah, and though it could be a variety, depending on what organ is involved as you mentioned.

Fred Hsieh, MD:

That's right.

Raed Dweik, MD:

That makes a lot of sense. So, what, let's say when somebody gets that high count eosinophil in the blood. What should they expect the follow up testing to look like?

Fred Hsieh, MD:

So, I think that often, we will repeat, or the clinician would repeat the blood test to make sure that the eosinophil count remains elevated, and then, at that point, they might begin to ask you more questions, examine the skin, and other organs more closely to see if there's any evidence of some abnormality that might suggest eosinophil involvement in one of those organs, or tissues.

At that point, the clinician might, or your physician, might order more blood testing, it could be for any number of things, including parasitic or other infections. They might order urine tests, or even stool tests, depending upon your travel history, or exposure, or occupation, and then, a lot of the workup would be targeted on the symptoms that you're experiencing, in terms of the specific target organ.

So, if you've got a new skin rash that you've never had before, then yes, probably you should have evaluation with dermatology, and they might do a biopsy to see what's going on there. If you're having cardiovascular symptoms, chest pain, shortness of breath, swelling in the lower extremities. Indeed, you might see cardiology in the workup, and they might get an echocardiogram, ultrasound study of the heart to see, look at the function of the heart, and they might do even more invasive procedures if they saw something abnormal.

If you had chest symptoms, you certainly might get pulmonary function tests, chest imaging, an x-ray or a CAT scan, or something like that. If you're having GI symptoms, especially if they're new, if you've got bleeding, something like that. Then, certainly the evaluation would be targeted there with a visit to your gastro, GI, gastroenterology provider. Probably, they would do some endoscopic evaluations with biopsies.

If you're having a new foot drop, or other neurologic symptoms, you might be going to see a neurologist. Uh, they might do a nerve biopsy, or something like that. So, a lot of the work up would be targeted at trying to see whether or not a particular organ, or tissue, has eosinophils in it. Are those eosinophils increased in number? Looking abnormal? Is there evidence of injury or damage to those tissues?

Raed Dweik, MD:

Yeah, it's amazing how many organs the eosinophil can infiltrate and cause damage to. So, now we will talk about treatment. I understand, now, based on what you said about the work up, that one, you must find out the underlying disease, and treat that, but let's say in situations where there's not a clear underlying disease. What’s your approach, or approach in general, to treat patients with high eosinophils?

Fred Hsieh, MD:

Well, I think what patients should recognize is that, especially if you've never been treated with corticosteroids in the past, that in almost all cases, or most cases, the eosinophil count can be rapidly brought down to a normal range with some dose of steroid therapy.

Now, it's not complete. It's not sort of a magic bullet in the sense that, certainly, there are some individuals that require very high dose steroids to reduce the eosinophil count into the normal range, but the corticosteroid type medications, both oral, intravenous, and versus otherwise systemic, can reduce the eosinophil count into the normal range, and then especially if whatever symptom you're suffering from improves, then that is some suggestion that the eosinophil is playing a role in the pathogenesis and the development of that disease.

The challenge, sometimes, is finding a dose of steroids that is not toxic to the patient long term, yet continues to control the disease, and sometimes that dose remains reasonably high, in which case then you must utilize what's termed as steroid sparing agent.

Some other medication that has a different side effect profile than corticosteroids that can help control the eosinophil count. I would say for the last 20 years or so, there have been several immunomodulatory type medications that have been effective, of which there is justification in the medical literature, but are not officially FDA approved for the treatment of hypereosinophilic syndrome.

However, recently, there have been a number of agents, some of them in the chemotherapy class, depending upon, you know, their reason for the hypereosinophilia, that have been utilized to treat hypereosinophilic syndrome, and then more recently, a biologic agent, or a medication that's given by injection on a regular basis that targets eosinophils has been approved by the US Food and Drug Administration for the control of hypereosinophilic syndrome, where no other hematologic cause, primary hematologic cause, is found.

So, there have been work advancements in the area to try to develop products that can help patients control eosinophilia and reduce the number of steroids they need to take.

Raed Dweik, MD:

That's good to know that there's some options. So, with that in mind, again, I talk about the prognosis here, to give people a sense of what to expect, you know, prognosis wise. I mean, I get it now, from what you said, that it depends on the underlying disease, but in general, can you share some prognostic information with our patients and families.

Fred Hsieh, MD:

Yeah. I mean, if you have eosinophils involving a specific organ, then likely, the prognosis would be very different than if you have hypereosinophilic syndrome, which is a multisystem, multiorgan disease, but really with a prompt to recognition, workup, and then institution of appropriate therapy. The mortality from hypereosinophilic syndrome has dramatically decreased over the last 10, 15 years, and so I think that if, you know, if you're a patient that has these conditions, and you've had the aggressive workup that demonstrates where the eosinophils are, you know?

Which organs are being attacked, or involved with the eosinophils, then you can really reduce the mortality from this condition.

Raed Dweik, MD:

Wonderful. Anything else you'd like to add? I think we covered a lot of ground in this podcast. Anything else that you'd like to add to our audience?

Fred Hsieh, MD:

Well, I would say that, you know, if you do have a complete blood count that show elevated eosinophils, I would say, pursuant to your initial comments, (laughs) don't panic, and a lot of it depends upon how long it's been there, how high is the count, and what symptoms do you have, and if this is something that was sort of identified incidentally, and you're not having any acute or active symptoms from this number, the eosinophil number in the peripheral blood, then you know.

It's not that you don't have to worry about it, but it's not like this is something that needs to be corrected tomorrow with a medication, like a steroid, and this is something that, you know, the provider can follow over a number of weeks, or months, and workup appropriately, and send you to a specialist if there is a requirement for further evaluation.

Raed Dweik, MD:

Yeah, I think you really summarized points for our audience. So, if you have a high eosinophilic count, don't panic, but don't ignore it, either, you know? It's something to pursue and find the cause for it. So, you know, don't give up on it, especially if it's very high.

You may want to see a specialist, and the number I heard you mention is 1,500. I know it's an arbitrary number, but it looks like it's been used in literature. So, if your number is more than 1,500, you want to be seen by somebody who really has seen these patients before. I think that would be good advice for our patients.

Fred Hsieh, MD:

I agree.

Raed Dweik, MD:

Yeah. Wonderful. So, thank you, Fred, again, for bringing this very difficult topic for us about eosinophilia, and high eosinophilic counts, and thank you to the audience for joining us today. Again, I'm your host, Raed Dweik, chair of the Respiratory Institute, and my guest today was Dr. Fred Hsieh, who is the Director of the Fellowship Program of Allergy Immunology, and the Vice-Chair of the Department of Allergy Immunology at the Respiratory Institute at the Cleveland Clinic, and our topic today focused on the eosinophil and the high eosinophilic count in the blood.

Thank you and have a great day. Thank you for listening to this episode of the Respiratory Inspirations podcast. For more stories, and information from the Cleveland Clinic Respiratory Institute, you can follow me on Twitter, @raeddweikmd.