Transcript: Determining The Cause Of Microscopic Hematuria

​Liz Rohr:
I want to start with a couple of key points.

Number one, please don't ignore this. I don't have too many pet peeves in primary care, but that is absolutely one of them. And then the number two is that I just want to remind you if you're not already familiar with this, or if you are as a reminder that a dipstick is a beautiful, so helpful tool and also it is a chemical reaction.

Well, hey there, it's Liz Rohr from Real World NP, and you are watching the Real World NP YouTube channel. We make weekly episodes to help save you time, frustration, and help you take the best care of your patients.

So this week's episode, we're going to talk about microscopic hematuria. This is something that we see all the time in primary care. And what I'm going to do in this episode is really talk about this high-level approach of what to look out for, approach to assessment, diagnosis, and then just pearls of practice along the way. Like I said, I'm going to keep this a bit high level, but there are very much specifics of what to do when, and all the differentials included inside the Lab Interpretation Crash Course. It comes with a continuing education, about eight plus-ish hours. We're in the middle of reaccreditation right now, maybe some more hours, we'll see. But that all of that is https://realworldnp.com/labs. It is not the only lab interpretation course, of course, however, it is a support there if you are looking for it when it comes to dipstick, urinalysis, all of the renal labs, it's so good.

But anyway, let's talk about microscopic hematuria. So I think first things first. What I want to say is what is microscopic hematuria? So this is blood that's detected on a urine sample, typically by a dipstick. It's not visible to the eye. It's not overt blood in the urine. It's just we did a dipstick and now we see a little bit of blood in there and we're like, "What's going on?" We're trying to figure out why. So that's the definition. So it's either 0 to 3+ on a dipstick, or if we're talking about urinalysis, which is the one that you send out to the lab and they spin it around and they let you know what's inside. That's about two to three red blood cells per high powered field, is typically how it's reported. And there are different organizations, say it's two red blood cells per high powered fields, some say it's three, etcetera.

So if that's a definition, I want to start with a couple of key points. Number one, please don't ignore this. I don't have too many pet peeves in primary care, but that is absolutely one of them. And then the number two is that I just want to remind you if you're not already familiar with this, or if you are as a reminder that a dipstick is a beautiful, so helpful tool, and also it is a chemical reaction. And so what it's doing is reacting to the substances in the urine and then it's changing colors, and then you interpret the color to correspond with like, "Oh, this dark purple color means that it's two to three red blood cells or 2+ red blood cells." So just as a reminder or first time learning, when we have anything on a dipstick that we are not clinically managing the patient in front of us, which hold that thought, I'll explain that more, we do want to send it out for confirmatory testing with a urinalysis.

So again, there's a bunch of caveats in there, but just generally speaking, if you have any doubts about what's in front of you, we do want to confirm it, right? This is very patient-dependent though. So I just want to give that little disclaimer. So the next piece is we really want to think about history before we get into diagnosis and management. So there's typically two presentations that I see of microscopic hematuria. One is that somebody came in with specific symptoms. So they had dysuria and I'm working them up for UTI or something else. Or maybe they have abdominal pain or flank pain, and I've gotten a urine sample to help put that clinical picture together. However, there's a number of people that present that have no symptoms at all, and they've just incidentally found this microscopic hematuria.

So the next piece I want to talk about is regarding the symptoms or not symptoms. So typically speaking, if you have hematuria, you really... microscopic hematuria, again, not overt, we're talking about looking at the patient in front of you. Why did you order it in the first place? Do they have abdominal pain? Do they have flank pain? Do they have dysuria? And you really do lead with hematuria is a clue for the clinical picture in front of you. You're really not leading with hematuria is the "problem." It's like, "Oh no, we want to help the whole person. Let's lead with that first." But the next piece I want to talk about is those microscopic hematurias that are incidentally found with no symptoms because those can feel a little frustrating for nurse practitioners. So what do you do when they're asymptomatic and you just happen to find 2+ blood on their urine dipstick.

So like I said, let's start with history. So assuming they're asymptomatic, I love to think about this in a structural way. For the most part when it comes to microscopic hematuria, is a little pearl here, is that it's typically either coming from a urologic source or from a kidney source, nephrology. And so that's the kind of piece of main places that the differentials fall into, is like, "Is this a urologic cause or is this a kidney cause, nephrology?" However, there's a couple of other etiologies we want to think about in broad categories. So medications, there's a handful of medications that can cause it. We also have these things referred to as mimics. I call them mimics, I don't know if everybody else does, but they're kind of the other sources of bleeding that is tricking you to think that it's actually in the urine, but it's not.

And typically this is coming from vaginal sources, perineum, maybe there's a rash or lacerations or things like that, or rectal sources. Those are the kind of main buckets of categories you want to think about of where could this potentially be coming from. The next piece is what are the other... Of course, you want to do your physical assessment, GI, GU, other body systems depending on the history of the patient. But in terms of the workup of the hematuria, the next thing you want to think about is what are the other labs showing us? And so the main first lab that you want to think about is the rest of the urinalysis, the rest of the urine dipstick and/or urinalysis if you're going to send it out. And typically if you're not treating them on the spot for a UTI or something like that, typically you're going to send it out for confirmation.

Versus if you had somebody who was menstruating who has a uterus and at that time they had their menstruation, so maybe you just want to repeat it next time. Anyway, like I said, all the caveats and details are inside the course, but I'm just trying to give a very high-level thing for this episode. So yeah, you're going to look at the rest of the urinalysis and the urine dipstick. And the main key things you want to think about, especially with hematuria, is protein and white blood cells. Those are the most next important things to look at. Because like I said, we're truly trying to break it down, is this a urologic source or is this a renal source? And depending on what you're looking at, renal sources tend to have more findings like white blood cells or protein or other findings in the urine. And then typically, again, this is generalities. Typically speaking, the urologic sources tend to have solely microscopic hematuria and they tend not to have protein or white blood cells for example.

I do get a lot of questions about urine cytology. And so urine cytology in the past was used to look at the cells of the urine to see if they were cancerous-looking cells with persistent microscopic hematuria is no longer recommended because it's not sensitive or specific enough. After that though, once you've looked at those pieces, if you're leaning more towards a renal source based on the breakdown of your urinalysis, what are the other tests that you want to do, how do you work up renal problems? Typically, want to look at BUN, GFR, things like that. And then versus are we leaning more towards a urologic source or are we leaning more towards another extragenital source.

So in terms of getting into the specifics, I really want to keep it as high level as that. The next steps are really dependent on where you're going with that. And then do you refer them to their specialist, nephrology, urology? Do you order any sort of testing before they get there? It really depends on the patient sitting in front of you. But hopefully this is a really helpful overview of microscopic hematuria, where to go.

Just as a recap, number one, we don't want to ignore it. Number two, we probably want to confirm it with a urinalysis send out. However, is really dependent on the person sitting in front of you, whether or not they have symptoms or no symptoms. Typically no symptoms, you're going to go on that further investigation of like, "Do we need to repeat this because they have menstruation today?" versus "There are medication that could be causing it" versus etcetera, etcetera. And then the next thing of course, we want to think about in terms of history of identifying those big buckets of etiologies.

Do they have symptoms? Do they have flank pain, abdominal pain, dysuria, or no symptoms at all? Versus are we thinking about a kidney structure, a urologic source? Is it a vaginal source? Is it a perineal skin source? Is it a rectal source? And then we can further break that down based on looking at the further urinalysis components of protein, white blood cells, other things, and then we decide who to refer to and what further workup steps we take depending on those pieces.

So hopefully that is a helpful overview for microscopic hematuria. Like I said, inside the Lab Interpretation Crash Course, we really go through this step by step by step and talk about all the differentials and where to go and how to interpret those results. But yeah, so that's available for you if you would like support with that.

But hopefully this is a helpful episode to get you going with microscopic hematuria.

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Thank you so much for tuning in. Talk to you soon.