Tobie O'Brien (Host): Today we are pleased to have Rebecca Kahler with us. Rebecca is a family nurse practitioner in our hematology department. We are so excited to have her with us. Today we plan to talk a little bit about our CBCs and what goes along with understanding a CBC and a CBC with differential and what it means for our patient.

And we're hoping that she can kind of break that down for us a little bit more. Rebecca, welcome to the podcast. And why don't you tell our listeners a little bit more about yourself.

Rebecca Kahler, APRN, FNP-BC, ONC: Hello everyone. Thank you for joining us, and expressing interest in knowing more about a CBC. I have been a nurse, nurse practitioner, for 47 years, and I have worked in a variety of settings. Those settings include ED, trauma, SICU, MICU. They've done pediatrics and adults, oncology, hematology, and pediatric stroke.

And I have enjoyed my career immensely and look forward to always grow and learn more as things change every day with us.

Trisha Williams (Host): We are so excited to have you shed some light on, lab work for children. I think that, it's a very confusing thing when or how to order a complete blood cell count, when to have a differential added. So I would love for you to be able to shed some light on the infamous CBCD, and what that means.

I always love it when people are like, Oh, it's a right shift. It's a left shift. It's a viral. It's a bacterial. I would love to know some quick tidbits on how to figure the CBCD out.

Rebecca Kahler, APRN, FNP-BC, ONC: Well, I hope I can do that today. There's a lot of components to the CBC. Actually the CBC with differential is one of the most common lab tests that are performed and it's power packed with information. The easiest thing to do is lay it down and then start with things that you're most familiar with of the CBC.

So a CBC has different components to it. It has the hemogram, which is the red blood cells and the platelets. Then it has differential with the white blood cell count. And it's actually known as a white blood cell differential. So the RBC in itself provides us right off the bat, when we look at it, we usually focus on hemoglobin and hematocrit and see if our patient is anemic.

That usually stands out at the first and then some people, depends upon the area where they work, will slide down and go to the platelet function and see if we have low platelets or high platelets. Other people will slide right down to the WBCs and that differential of all those little small cells that make up that WBC.

So how would you like me to start?

Tobie O'Brien (Host): Well, let's start with the WBCs because I feel like that is the first thing I look at. What about you, Trisha?

Trisha Williams (Host): Yeah, I would agree. Like as long as my hemoglobin and hematocrit are good, I go to the WBCs as well. So I think starting there is a good idea.

Rebecca Kahler, APRN, FNP-BC, ONC: That's interesting because if you ever look at literature that's out there, the WBCs is the first one that is covered in an article, which I found unusual too, when I was refreshing for this visit today.

 So the WBCs, when I say differential, that includes all the little small cells that make up the bunch of WBCs. The WBC is called leukocytes. They're the major players, of course, as we know, infections and inflammatory immune response, but it can be divided into two main groups. Have you ever thought of that when you look at a WBC?

Trisha Williams (Host): No, I have not , in all honesty, no.

Tobie O'Brien (Host): Well, I doremember the portion about there being like baby white blood cells. Um,that part I remember.

Rebecca Kahler, APRN, FNP-BC, ONC: Right.

Trisha Williams (Host): I wonder if we can make a song about it, like Baby Shark, baby, blood cells, doo, doo, doo, I don't know.

Rebecca Kahler, APRN, FNP-BC, ONC: That would be interesting.

Trisha Williams (Host): Right? I'm not gonna do it, though.

Rebecca Kahler, APRN, FNP-BC, ONC: So there are parts of the white blood cell that is a phagocytotic, so it eats everything up. And then there's parts of the white blood cell, that is the immunocytes, so they fight off infections. That's where you get all the granules like neutrophils, eos, basos, all of those little words that go below that, and we see those numbers pop up, that's where all that feeds into.

It depends on which group that you're dealing with.So, for example, a granulocyte gets its name from having, it's full of granules and they serve as an inflammatory response and immune response. And what's interesting is they take a week to develop in the bone marrow and they only circulate for 6 to 12 hours.

So if there, you have an elevation in granulocytes, they're busy tearing something down and fighting something that's going on. Neutrophils, they're called the segs, they are there to do nothing but ingest microorganisms and debris, and then they die. They're gone. The eos, or the eosinophils, they ingest and kill parasites.

Frequently, we'll look at eosinophils if we have someone who is having an allergic reaction, if they have a hypersensitivity response to something, or even if they have asthma, atopic rhinitis, they can be elevated for those kind of diagnosis. The basos, they are associated with the systemic allergic reactions.

So whatever the eos are doing, the basos are coming right behind it, taking care of it. The bigger ones we all know about are the microcytes and the macrophages. They're the largest of the white blood cell count. They're circling around all the time and they usually enter into the bloodstream immature and then they go and live in tissues and whatever tissue they're named by that tissue that they're living in and then they mature.

It takes them about a day to mature, like the Kupffer cells that live in the liver. You guys familiar with those?

Trisha Williams (Host): Yes, that I do remember.

Rebecca Kahler, APRN, FNP-BC, ONC: Yeah. Well that's where those live, okay?So they're busy eating up and taking care and keeping things clean and breaking debris down and also fighting the infections that may be going on there. The lymphocytes, we're all familiar with lymphocytes. Yeah, right, they're the numerous, they're circulating around all the time and they're T and B lymphocytes.

And then we also have the natural killer cells too. So I don't think I'll go through the T and B action because I think we both, we all know how that happens. But know that when you have a neutrophil count that's high, it's commonly caused by an acute bacterial infection. And they always increase within four to six hours after the infection or the invasion occurs.

So, when you're looking at your neutrophil, they can be low or close to slightly elevated initially, but then as the infection stews on, they can become greatly increased and you'll have a sharp rise in it and it'll match the symptoms of your patient. One thing I do want to stress through all of this, nothing takes the place of our assessment of our patients and the patient's symptoms because they tell us a lot, right?

Tobie O'Brien (Host): Right.

Rebecca Kahler, APRN, FNP-BC, ONC: Okay, then always there's this big question. What's a left shift? What's a right shift, right?

Trisha Williams (Host): Yep.

Rebecca Kahler, APRN, FNP-BC, ONC: I'm going to be honest ladies, I have never been able to keep this straight and I have to remind myself, which way am I going here?

Trisha Williams (Host): I'm so glad I'm not alone. I

Rebecca Kahler, APRN, FNP-BC, ONC: It's a dance. So, if you have an elevation in the segs, then it's considered a right shift and when that happens tissue is breaking down from injuries, burns, arthritis, hemorrhage, or shock. And that pretty much fits what we see here at Children's Mercy in our population. When you have an elevation in bands, it is referred to a left shift and that is when there's an increase of immature neutrophils and they've been released by the bone marrow and the reason why they're being released immaturely is because there's an overwhelming infection and the mature neutrophils are depleted.

So that person is in a high risk for being immunocompromised. Which fits with a lot of the places or childrenthat we see in different areas of Children's Mercy, right?

Trisha Williams (Host): Yeah.

Tobie O'Brien (Host): Right.

Rebecca Kahler, APRN, FNP-BC, ONC: So, it is, that is like a white blood cell count. You know what's interesting is, we will have children referred to us with a low neutrophil count, and the rest of their lab is beautifully, it's all within normal limits, but they've been plugging along with this borderline low neutrophil count, so the bottom end of a neutrophil count is 1500.

And they're running 5, 6, 7, in that range. Sometimes they'll bounce up to 900. So what we usually have to do is follow these kiddos to figure out what's causing this. And their labs never change. However, there's two sides of the white blood cells, remember? So we go ahead and look at which side we're going down, whether something's happening with the immune system, or is there something going on as far as an infection?

So the challenge becomes, which way we go to figure out what's causing this. what gives us a good answer; is when a child has an infection, look at the neutrophil rate. It'll go up if it's an immune response. It'll go into normal. The neutrophils will come and fight. If it's a phagocytic, then the damage has already been done and the neutrophils will be normal to dropping down a little bit because they're being used up so fast from the bone marrow, but they come back up and they're in normal range. So that's how we separate things out when it comes to neutrophils. And then there's something called Daphenol. Daphenol is high in Asians and African American populations. Middle Eastern, I'll say, is included in that, and what it is, is they literally, immunity wise run low neutrophils. Everything else is normal, and even when they get ill, they don't have a stress on their system and it's just constantly borderline to low, above 500, is where their neutrophils sit. We can do some genetic testing to figure that out and land on it when we watch these kids for six to eight months, sometimes nine months, and we really don't have an answer and the parents say that they're really not sick. So, we go ahead and then do the genetic testing to find out if that is what's going on with them.

Other questions about white blood cells?

Tobie O'Brien (Host): Yes, I do. I have a question. It sounds like it's pretty important to include that differential. I'm going to use an example because Trisha and I work in ENT. Say we are ordering some coagulation labs and we're going to order a CBC. How important is it to get that differential within the CBC?

Rebecca Kahler, APRN, FNP-BC, ONC: When we get through the differential within the CBC as far as the red blood cells, and then they'll give you your red blood cell indices, it's very important because you're looking for anemia, coagulopathy, and then the white blood cell in your area of environment would be looking to see if they have an infection going on, such as a sinus infection that can lead to other complications when they have them.

Or otitis media. I have a child right now, which I'm going to share the case study later, that has had 10 ear infections within six months. His CBC looks terrible. His neutrophils are off the chart. Then they dropped significantly because he was depleted. So he developed a left shift.

Tobie O'Brien (Host): Oh, Rebecca, that makes sense. Maybe if I look at it this way, so why would anyone then ever just order a CBC, but not include a CBC with differential if it packs so much information, the differential portion?

Rebecca Kahler, APRN, FNP-BC, ONC: That's a good question because if you check, it really doesn't take that much effort. It's still the same amount of blood that's drawn from the child. Usually the ones that do not order a differential are in those disciplines that they're not concerned about anything other than they're wanting to focus on the platelets, the hemoglobin, and the hematocrit. They don't need anything else. That's it.

Tobie O'Brien (Host): Okay.

Rebecca Kahler, APRN, FNP-BC, ONC: Based on whatever the child's presenting with and, what their focus is. You know, a differential costs no more than running a plain CBC.

Trisha Williams (Host): Okay, that was gonna be my question about, you know, cost efficiency and,things like that. So it's great to know that, there's no cost difference.

Rebecca Kahler, APRN, FNP-BC, ONC: That's correct. There's none.

Trisha Williams (Host): You had mentioned a case study and I would love to talk about that, and maybe kind of end on that, so, please, talk us through your case study.

Rebecca Kahler, APRN, FNP-BC, ONC: Okay, it will skip over white blood cells, okay? It's not dealing with white blood cells. So I picked some general ones that I currently have going on I have, an example this is a current child that I'm taking care of, a 11 month old male, who's had the otitis media x10 in 6 months, currently has otitis media, and he showed up in the emergency room here at Children's because he was running a fever of 102.2. He was on appropriate antimicrobial medications. He was put on amoxicillin, took the whole thing, didn't miss any doses. And he shows up in the ED because he's breaking out with bruises everywhere, everywhere. And the parents said they're not touching him or beating the child, as we know. So we ran labs on the child and the RBCs was 4.52, which is low. The MCV is what we looked at next, that's the size of the red blood cell, and we want to see if they are functioning or not, and they also shows if there's been immature ones.

It was 78, 76.8. His hemoglobin was 11.9, which is the bottom end of normal for his age, but his platelets were 4,000. Now, that could just be your CBC. You look at the red cells, the hemoglobin, the hematocrit, and the platelets. Platelets are four. You could stop your assessment there. By going ahead and adding the differential, your A and C count is 970, and the bottom end of normal is 1500.

So, this causes you to ask a lot more questions, what's going on with this kid. And, when you assess your child, like I told you, assessment is a big thing. You will see he's covered in petechiae, bruising, he looks kind of jaundice undertone, he's smiling and as cute as a bug. However, you can tell by his counts that he may be smiling, but there's something going on, right?

How do you have platelets of four? And you have an ANC that's low. So, first of all, you break it out. Platelets of four says thrombocytopenia. Thrombocytopenia can occur when children have chronic infections and frequent infections or multiple infections within a short amount of time suppressing the immune system, where it has no defense left, which drops your ANC, that means those neutrophils that are out there taking care of everything, the marrow is not able to keep up with replacing them, dropping their ANC.

So, I have a child that has all of these labs. Some of these labs that are abnormal with symptoms, looking at all of it together, I'm going to say this child looks like he has immune thrombocytopenia purpura.

Trisha Williams (Host): As you were going through that, that's exactly what I thought. I'm so proud of myself. Woo doo for you!

Tobie O'Brien (Host): So, and in my head, being ENT, I'm thinking, well, why don't we just do tubes and then maybe he's just gets better, but how do you fix that then? Is that something that will just be improved over time?

Rebecca Kahler, APRN, FNP-BC, ONC: You'll get to see him.

Tobie O'Brien (Host): Oh, good.

Rebecca Kahler, APRN, FNP-BC, ONC: Yes.

So what we usually try to do is to see if the immune system will quit attacking itself. We actually follow them until they develop bleeding and we've had platelets go down to one and we still observe. When a child is in the toddler age and they're going to fall over, you know, and they start having more and more petechiae, we want to protect their head.

 One to three percent of children that have low platelets will develop a bleed in their head. Very low percentage. So we don't put a helmet on them or anything of the sort. Instead, we start them on steroids and we see if that'll bring up their counts. And if it does, great. After the steroids, five days, we evaluate their labs again.

If they have no response, such as this child, then we give them IVIG. Stimulate overproduce the immunoglobulins in the blood to shut down the ones that are fighting and killing off the healthy cells. So we give them IVIG. This child failed IVIG also. So now he has a platelet of two. He has bloody nasal secretions and yesterday he had blood in his stool.

So, he has to move on to something more aggressive, correct? We don't give platelets because the immune system is going to gobble him up as fast as we give him. So we can't give him that. So this child will move on to rituximab.

It fights the immune system and shuts it down for a while and actually resets the bone marrow from functioning. It is like what is that big red thing that people would have on their desk? Pause or stop.

Trisha Williams (Host): The big stop button. Yeah.

Rebecca Kahler, APRN, FNP-BC, ONC: Yes, and that is exactly what rituximab will do. We'll give him four infusions of that. Hopefully we can get the immune system calmed down enough or stop and reset itself. So he starts having a normal, normal counts and stops bruising and having so much petechiae and bleeding.

Tobie O'Brien (Host): That's an interesting case for sure.

Trisha Williams (Host): Exactly what I was thinking. All of the, from one of the most common illnesses in children, from ear infections, right? The body is just amazing to me. Well, thank you so much for sharing that case study. That was absolutely amazing.

Rebecca Kahler, APRN, FNP-BC, ONC: Good. I'm glad you enjoyed it. it

Trisha Williams (Host): Yeah.

Tobie O'Brien (Host): Yeah. And I think it was really helpful for you to go through just the CBC top to bottom so we could kind of have a better understanding. I know it helped me. And so I'm hoping it will help some of our listeners out there. So thanks so much, Rebecca, for helping us and using your expertise to fill us in.

You are very knowledgeable. So I know we're only like barely scratching the surface. It's so intricate and very involved and definitely more complex. But I think that this was a great start to diving in a little bit deeper, maybe on our own. But thanks for kind of getting that rolling for us.

Rebecca Kahler, APRN, FNP-BC, ONC: You're welcome.

Tobie O'Brien (Host): We like to end each episode, with the same question of like in each season. And so today we want to ask you, what your younger self would high five you for now?

Rebecca Kahler, APRN, FNP-BC, ONC: My persistence, yes. I feel we are not in a profession. I'll use the example my son has. He's an engineer. He's an electrical engineer, highly intelligent. You know, they get boxed in and they do certain things over and over again. Now, yes, he is learning AI and going through that process now, but in our field, we get to grow.

We can be like an octopus. We come with this core set of information and then we get to spread out in our legs in any direction we want to go and we continue to learn and respect the career that we're in. And so that's one of the greatest gifts. So persistence is the only thing I can make for 47 years of nursing career, so.

Tobie O'Brien (Host): I love it.

Trisha Williams (Host): I know, I, needed to hear that analogy, Rebecca, I have kind of been in the dumps lately. I don't know what the verbiage is, but you know, just kind of needing some inspiration in my career and, to think about it as an octopus. Beautiful. Beautifully said. I love it. I might even like print me a picture of an octopus and carry it around at work for a little while.

You just inspired me.

Rebecca Kahler, APRN, FNP-BC, ONC: Oh, good. I'm glad. Thank you, ladies, for inviting me again. I,hope I've accomplished what you set this out to be.

Trisha Williams (Host): We are so lucky to have you and thanks again for jumping on.

Rebecca Kahler, APRN, FNP-BC, ONC: You're welcome.

Tobie O'Brien (Host): Thanks again and thank you all for listening to the Advanced Practice Perspectives podcast.