Anemia Diagnosis: Lab Interpretation for New Grad NPs
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Show notes:
How often do you open your EHR to find lab results that are slightly abnormal, but you're not sure if you need to worry about them?
Lab interpretation for new nurse practitioners can be confusing!
Anemia is a huge topic, but in this case study, I'll be walking you through a common pattern of labs that I see all the time in primary care.
Diagnosing Anemia in Primary Care
In this video you'll learn:
The alarm signs of anemia (and the lab values that go with them)
When to send someone to hematology
The MOST important lab values to look at (and some lesser known ones that can give you a lot of insight)
The tests you may want to order to give you more clarity
Continue Learning: Lab Interpretation Series Bundle
If you liked this episode, it's a sneak preview of how we cover labs inside our comprehensive Lab Interpretation Series Bundle. It’s an ANCC-accredited CE bundle of courses that covers CBC, BMP, Renal Labs including Urinalysis, Dipstick & Microscopy, Microalbumin, TSH, and Hyperlipidemia in primary care! Check it out here.
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Liz Rohr:
Well, hey there. It's Liz Rohr from Real World NP. And you're watching NP practice Made Simple, the weekly videos to help save you time, frustration and help you learn faster so you can take the best care of your patients. So today I'm going to be talking about anemia. I'm actually going to be covering a case study with a lab result interpretation that you've probably seen before, and you haven't really known what to do with it. So I hope it's really helpful. An important note is that anemia is a really big topic. So I'm really only covering a small portion of it. If you're interested in learning more, if you want to feel more confident with your CBC interpretation and lab interpretation in general, definitely come join me for the lab interpretation crash course for new nurse practitioners. The first edition is going to be launching mid-November with a limited number of spots. And then the full thing is going to be happening in mid-January.
So definitely head over to realworldnp.com/labs to join in. But with that, without further ado, I'm going to share my screen with you. So let's jump right into the anemia case study. So this is Lisa, she's 46 years old, female, she's a new patient establishing care at the clinic. And again, this is not her real name or her photo. So she's got no concerns today. She's here just to establish care. She's switching clinics, meeting you for the first time. She was told that she had anemia in the past. She's not sure what treatment she's done. She may have had iron. She can't really remember, but she said that she was told it was fine. She is a non-smoker, does not drink alcohol or use other drugs. She's a single mom, no sexual partners. And then she said that she had STI testing recently, and hasn't had any partners since then.
And everything she said was normal. So past medical history, question of anemia, otherwise she says she's been pretty healthy. Family history of hypertension. Her mom has some mild high blood pressure. No past surgical history, no medications. Her blood pressure, heart rate, BMI are all normal, as well as her oxygen and her temperature. So making it pretty easy for us today. So a plan I'm going to be talking about labs today. I'm going to touch on the other components of holistic care at the end, like the other case studies. So for labs, I'm going to keep it really conservative, right? So she's 46 years old. She has a history of a question of anemia. So I'm going to check a CBC. She's asymptomatic luckily, but I do want to kind of investigate that just to make sure it's all right. I'm doing a basic metabolic panel.
We could have a whole discussion about testing and all that. And over-testing and under-testing and all that stuff in terms of lab tests. So I added that on for my own reassurance purposes. I don't necessarily have a very good clinical reason aside from just kind of getting some baseline information. But other than that, I'm just trying to work in my own practice on ordering less blood tests than more. There's a pretty standard one that everybody gets, which is a CBC, a CMP, a TSH, lipids, A1C, all that stuff. But because she doesn't really have any risk factors, she's 46 old, no early family history of hyperlipidemia or MI or anything like that. I guess I could have added a lipid profile, and maybe we'll discuss that more when she comes back for her physical.
Also, I'm going to look at her previous labs. But anyway, that's a longer discussion, but pretty much I'm just looking at the CBC and the BMP today. So here are our results. Our BMP was totally normal. So this is a really common lab pattern that I see. So her hematocrit, if you're listening to this instead of watching, hematocrit is 33% for the reference range for this lab is 35 to 45. Hemoglobin is 11. And the normal range is 11.5 to 15.5. MCH, MCHC are both normal. The MCV is 77. So slightly below the normal of 80 to 100, or this lab is 80 to 94. Platelets are normal. Red blood cells are 5.5, the normal range upper limit being 5.1. Her RDW is normal, 13.9. And then her white blood cells are also normal. So really the main abnormalities here are the low hematocrit, hemoglobin and MCV, and high red blood cells.
So I see this lab all the time. I wonder if you've seen this lab pattern as well. So I'm going to jump into anemia. It's a really big topic, but I'm going to really focus on this kind of case study and tie in some other things as well. So low hematocrit, hemoglobin and RBC question mark, because anemia, typically you think of being low hematocrit, hemoglobin and low red blood cells, but we got some high red blood cells. So I wonder if you can guess kind of what's going on, but I want to do a brief overview of the CBC components. So white blood cells, if you saw the WBC lecture, that's all about the leukocytes, the number of leukocytes. Hematocrit and hemoglobin, hematocrit is the concentration of your plasma of the red blood cell kind of components in proportion to the rest of the plasma.
The hemoglobin is the protein that carries oxygen. And the note about that is that the lab will ... That's an accurately measured component in terms of the CBC is ... The hemoglobin is directly measured where some of the other components are calculated. So if you're looking for something that's kind of reliable, the hemoglobin is kind of the one to look at. Red blood cells is the number of cells. And so typically you would expect that the number of cells would correlate with the hematocrit concentration, which doesn't always, as in this case. MCV is mean corpuscular volume. So that's the red blood cell, cell size. That's really important. RDW is the red blood cell distribution width. And what that means is that when you have blood existing currently in your bloodstream, our red blood cells turnover about every 120 days, correct? So the ones that currently exist compared to the ones that are being produced, there is a size differential.
So instead of them all being normal, they're abnormal or they're smaller or larger than what currently exists. So when you have something like some types of anemia, for example, iron deficiency anemia, you're going to as your iron stores drop, you're going to get smaller and smaller cells being released. And so your RDW is going to increase because of that. So platelets repair injury to the vascular epithelium, they're important for blood clotting. I'm not going to be talking about that in this lecture. And MCHC and MCH, just a really quick note about that. So it's the average hemoglobin per red blood cell, and it's just not very useful of a measure. So I'm sure you've learned about it in school and the microcytic hypochromic cells that commonly come with iron deficiency anemia, you'll have that kind of abnormality. Honestly, hematologists are not really even looking at that.
It's really not that relevant. And if you see something that just has MCHC or MCH abnormal and everything else is normal, don't worry about it because that kind of flu cabins quite frequently I think. So five steps to an anemia workup in general. So number one is, do they have symptoms? And that's pretty much for any lab that we're talking about or any lab that you're looking at is your first question should really be, do they have symptoms, right? And how low is it knowing your thresholds of what's important in terms of emergent versus outpatient workup? Number three, I want you to reflexively look at when you have low hematocrit and hemoglobin, reflexively look at the MCV, the mean corpuscular volume, the size of the cells, which you probably learned in school. Again, maybe that's just a review, but, and then the other thing to think about is plus or minus the smear.
So if you listen to the white blood cell or watch the white blood cell video, I really talked about the smear quite a bit and how important that is when you're interpreting a CBC. So go back and watch that if you haven't watched that already, but that's really important, depending on kind of how you go with anemia. Number four is looking at the trend over time. That's definitely kind of a mistake that I see of, of new grads looking at lab interpretation is that they're not really comparing to the previous one. So you might get a hemoglobin of eight, which sounds really scary. But if you look at the last blood test that was done three months ago, the hemoglobin was also eight. So looking at that trend is really important and number five is comorbidities. So I'm really not going to be talking about anemia [inaudible 00:07:58] chronic disease today, but that's something to think about.
That's really important when you're interpreting any kind of anemia, putting the clinical picture together. It's not really just about the numbers and the shapes and all that stuff. You really have to look at the big clinical picture. So this is a kind of anemia workup pretty briefly. So the normal range for hematocrit for women is 37 to 47. And the hemoglobin is 12 to 16 approximately. For men, the hematocrit is 42 to 50%, and hemoglobin about 14 to 18 and the upper limit of 18 for certain conditions, we're not talking about high hematocrit today, but if you're thinking about high hematocrit, it may or may not be 18. It might actually be a little bit lower, 16, if you're talking about certain conditions that you're investigating, but side note on that, but we're talking about anemia today.
So hemoglobin of 12 for women, hemoglobin of 14 for men. So if you have a hemoglobin of less than seven and/or they're symptomatic, like they have hypotension, they're tachycardic, obvious signs of bleeding obviously. Those people are going to need to go to the ER, right? Because that's really concerning. But if it's above seven, around seven if they're symptomatic as well, or any obvious signs of bleeding, definitely send them if it's eight or something like that. But if it's above seven and it's under that 12 to 14 for women and men, the first thing you're going to look at is the MCV like I kind of said. That should really be reflexive for you. So if it's less than 80, you're thinking about microcytic anemia. So those are small cells, which has a different differential than normocytic, which is 80 to 100 versus greater than a hundred is going to be your macrocytic.
And depending on where your MCV is, it's going to bring you down different paths, right? Maybe that's a review for you, but just, it's a good way to conceptualize it. And so, oops, I didn't animate this slide very well, but testing for anemia that you can think about for microcytic anemia, you can consider doing some iron studies. So that's ferritin TIBC and serum iron are the main iron studies that are recommended. And a reticulocyte count. So reticulocytes are the kind of early red blood cells. And then I'll give you an idea of whether or not the bone marrow is responding to the anemia and able to produce more red blood cells or not. And that will give you kind of clues about where to go in your investigation, whether it's high or it's low. And you also want to consider adding a differential or a smear, peripheral smear for abnormal looking cells.
And then if you have those, that'll kind of give you further clues about what type of microcytic anemia we're talking about. And so this should've come up first, but microcytic anemia again is less than 80 of an MCV. Iron deficiency is your number one reason just globally, but also in the US. Number two is anemia of chronic disease and chronic inflammation. So those are people who have rheumatoid arthritis or even diabetes or heart problems. They can kind of have this chronic inflammation affiliated with that disease state, which kind of causes impaired ...
And it causes an anemia. It's kind of a lot to get into, but just knowing that that's an option in your differentials for this patient and hemoglobin apathy's are pretty common. And I'm going to talk about that on the next slide in just a sec. And then the other thing to kind of consider less common, myelodysplastic syndromes, like aplastic anemia or other kind of hematology/oncology etiologies are something to really consider. So, and that's why you would add on a smear, right? Because does the clinical picture make sense? Does it seem like it's one of those top three or does it not? And then you look at the peripheral smear, there are abnormal cells, there are other components of your CBC that are abnormal, the white cells, the platelets, things like that. That'll kind of cue you to think about like, Oh, okay.
Like this is not just a garden variety, microcytic anemia. This is because of a larger hematologic oncologic process, right? So hemoglobinopathies, there are many types, right? So, but the most common lab, excuse me. So spoiler alert, the most common lab pattern that I see is a microcytic anemia with high red blood cells and a low reticulocyte count. And this is kind of affiliated with alpha or beta thalassemia minor. So this is kind of what this patient has, spoiler alert, but there's major and there's minor, alpha and beta thalassemia is. So major, these people you would know if they had major, right? Because these people are transfusion-dependent pretty much for life. And you're probably not going to be diagnosing these incidentally on your CBC, right? Especially a 46-year-old woman. So this is unlikely to be a major thalassemia. Minor is whether it's alpha or beta tend to be asymptomatic.
So either they have a ... There's four different kinds of alphas. Side note, there's four different kinds of alphas and two different kinds of betas. Alpha one, there are no symptoms at all. Alpha two there's this mild microcytic anemia with high red blood cells. Three is that more major transfusion-dependent, and four is the hydrops fetalis cause. And those patients don't survive. Those in utero don't survive. So, and then for beta, there's only two. There's minor and there's major. So just fun facts about that. But yeah, so either they'll have no symptoms at all, or they'll have that trait, which is the mild microcytic anemia with a high red blood cell. So in terms of other hemoglobinopathies, there are other kinds, right? There's sickle cell, there's other things like that, but typically ... And you can check a smear and they'll have abnormal looking cells.
But again, if you have a 46-year-old female, this is unlikely going to be the first time that you're going to diagnose somebody with sickle cell, right? Because when they're a kid, this is a lifelong illness, right? This is not going to be the first time diagnosis. But if you're really not sure, check a smear. Just make sure that there's nothing else abnormal going on. Considering iron studies for this kind of pattern. And then these are likely going to be normal. There's a chance that you could have concomitant iron deficiency and hemoglobinopathy, but most likely they're going to be normal. And another test that you can do is a hemoglobin electrophoresis. The main reason to do this is because you're trying to get diagnostic clarity, right? It's going to give you some results that ... I'm not going to get into the interpretation.
I really don't order this very often, but it's going to give you different types of hemoglobin. That's going to give you hemoglobin A, hemoglobin A1, A2, hemoglobin F, hemoglobin E things like that. The main reason to order that is so that you can get diagnostic clarity. And then for people who have prenatal considerations, right? So if you are a trait carrier, you might want to consider if you're seeking pregnancy as a female or a partner, you want to think about genetic testing and recommending that for them. I'm not going to be doing that in primary care, right? And then don't treat them with iron. I think that's one of the main mistakes that I see is that you see a microcytic anemia, you think, oh, okay, it's iron deficiency. Throw some iron at them, but these patients can actually get overloaded.
So you just want to be careful. And if you happen to find iron overload on your labs, then you can refer them to hematology for treatment for that. And then a chemo referral if it's still unclear. If you're very uncomfortable, send them, right? If it's more significant than the minor lab that I've shown you, something to think about. Or if it's kind of a progressive, and it seems like it's not kind of stable chronic, right? So what's next for Lisa? So for her, most likely this is normal, right? It's probably an alpha or beta thalassemia minor. Her hemoglobin is greater than seven. She's asymptomatic. We're going to be requesting records from the previous PCP. It's a likely long-standing versus a new and developing problem because she again was told that she has anemia of some kind, and it's normal.
She's not taking any iron for it, things like that. So for any normal CBC, any sign of anemia, aside from people who are under seven or symptomatic ... Everyone needs to be rechecked, right? That's just a consensus guideline for general practice, right? Because no lab is perfect and who knows, right? So that's the general recommendation for most providers is to recheck it. But for the people who are seven or under or symptomatic, they need to go to the ER and they will recheck it there for them, right? Anybody else, recheck in about one to two weeks, considering iron study and reticulocyte count to verify it. And then also considering adding on a peripheral smear to assess there's any abnormal cells. And then also again, assessing to see if there's any signs of iron overload. Has this person been treated with multiple courses of iron because they were worried that they thought it was an iron deficiency, and didn't really think that through, things like that.
So, and I haven't discovered that myself in primary care, but if I did discover that iron overload situation, I would have them see hematology or at least consult with them to get recommendations of what to do next. And then again, discussing contraceptive implications. So this patient is 46. She's a single mom. She has no sexual partners. She has no intentions of having other children right now. She's using abstinence for her contraceptive method. But thinking about if she were to get pregnant, genetic counseling considerations there. So going back to Lisa, she's 46. Again, not her real name or photo. So I rechecked her hematocrit and hemoglobin in a few weeks. Again, it's not urgent. She's not symptomatic. I requested her records from her previous PCP. And I'm considering doing iron studies versus a reticulocyte count. I have a feeling this is longstanding.
So I'm not really that worried about it. She's probably had the iron studies done with her previous PCP. So I'm just going to kind of wait for those records to come through. And I've advised her of the alarm signs and symptoms, right? So is this a new anemia that's developing, and it was just a fluke that the RBCs were high? Does she have any fatigue, signs of bleeding, things like that? What are those alarm signs that I want to advise her of to come back with in the meantime. And then I'm just going to have her come back for a physical exam, just because that's kind of my flow of care for patients who are establishing care. I get their previous records. And then I recommend physicals once per year, just because it's important to touch base with them. Make sure there's nothing else that's going on with them. Kind of jumping on preventative health care.
And again, considering doing a lipid profile because she's over the age of 45, which I didn't do at the first visit, but we can have a discussion about that. And that's according to USPSTF's screening guidelines. And then the other things to think about are just screenings and vaccinations, right? For somebody who comes into established care. So when was her last PAP? Is she considering doing mammograms because she's over the age of 45. And that depends on if you're looking at USPSDF guidelines, or are you looking at ACS criteria? Is it flu season, right? They have this recording, this is definitely in the middle of flu season or starting of flu season rather. Tetanus every 10 years, hepatitis B series versus do we do a screening lab test for her to see if she has any antibodies or antigens, things like that.
Yeah. And then just waiting for those records. And that's it. Did you like this video? If so, hit like and subscribe and share with your NP friends. So together we can reach as many new grads as possible to help make their first years a little bit easier. And if you like this video and you want to learn more about CBC interpretation, anemia, feel really confident when you open up your EHR and you look at your lab results, come on and join me for the lab interpretation crash course for new nurse practitioners. There's a limited number of spots happening with the first launch in November, and then after that it's going to be available in mid-January. So if you're interested in hearing more, head over to realworldnp.com/labs, and you can sign up. And definitely head over onto realworldnp.com in general to get your ultimate resource guide for the new NP. You'll get these videos sent straight to your inbox every week with little notes from me, with bonus content that I just don't share anywhere else. Thank you so much again for watching. Hang in there and I'll see you soon.
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