Name:
S2D: The Symptom to Diagnosis Podcast - Episode 18: Edema
Description:
S2D: The Symptom to Diagnosis Podcast - Episode 18: Edema
Thumbnail URL:
https://cadmoremediastorage.blob.core.windows.net/54c12c6d-823c-45de-aff4-2600fd1634c5/thumbnails/54c12c6d-823c-45de-aff4-2600fd1634c5.jpg?sv=2019-02-02&sr=c&sig=HNfwZrzvUtJFhdY2EqxwLFGYbSURMx%2BPYNBoOXMVlV0%3D&st=2024-04-30T04%3A23%3A28Z&se=2024-04-30T08%3A28%3A28Z&sp=r
Duration:
T00H25M29S
Embed URL:
https://stream.cadmore.media/player/54c12c6d-823c-45de-aff4-2600fd1634c5
Content URL:
https://cadmoreoriginalmedia.blob.core.windows.net/54c12c6d-823c-45de-aff4-2600fd1634c5/18892522.mp3?sv=2019-02-02&sr=c&sig=eGKdS7%2Bkp6dw2NGrZL17phxgol5%2F5Ct8jtb938JW2oA%3D&st=2024-04-30T04%3A23%3A28Z&se=2024-04-30T06%3A28%3A28Z&sp=r
Upload Date:
2023-06-03T00:00:00.0000000
Transcript:
Language: EN.
Segment:0 .
[upbeat intro music] [upbeat intro music] [upbeat intro music]
DR. CIFU: I'm Adam Cifu.
DR. STERN: And I'm Scott Stern.
DR. CIFU: And we are here with another episode of S2D, the Symptom to Diagnosis podcast. This podcast teaches evidence-based strategies for diagnosing common medical symptoms. We begin each episode with a case unknown to one of us. We then discuss five high yield features that help to accurately diagnose the cause of the symptom at hand. We then return to our case before finishing up with a discussion of fingerprints, common misconceptions, pet peeves, and other random pearls of knowledge pertaining to the week's symptom.
DR. CIFU: The cases that we discuss are drawn from our clinical experiences but because protecting patient privacy is part of our oath, we never discuss actual patients and most cases are composites. What are we talking about today, Scott?
DR. STERN: I believe we're talking about edema, and you are the expert of the day, and I understand you have a case to present to me.
DR. CIFU: I do.
DR. STERN: Uh-oh.
DR. CIFU: You know, we try, we've talked about this, we talked about this while we were planning the podcast to not go with total zebras and make this like a magic show of trying to figure things out. And I think we would both agree that we think it's more important to learn how to do the common things perfectly before or at least as well as learning to do the uncommon things well. But this week I'm going with something unusual. But it's actually pretty straightforward.
DR. STERN: Okay, well, you're making me nervous but-- [both chuckle]
DR. STERN: --I hope I'm not a complete idiot, but go ahead with the case.
DR. CIFU: It's funny, I thought of this case and then when I actually looked it up to look in detail, I was like that's even a better case than I thought it was.
DR. STERN: Oh joy.
DR. CIFU: Okay, so this is a 65-year-old man who has well compensated alcoholic cirrhosis, and he calls on a Friday afternoon, of course, with about seven days of increasing lower extremity edema. Okay? And he says, "I basically never have swelling in my legs, I see a little bit of line at my socks at the end of the day but that's it." And he says, "Now, tree trunks." And I was like, "Really? And really seven days?" He goes, "Yeah, seven days." He's got no other symptoms, this is all on the phone, I asked him a ton of questions.
DR. CIFU: The only thing I could get out was that he says, sometimes he's got some kind of palpitations in the morning and that's it. He's got cirrhosis with varices actually but perfectly compensated. He's got high blood pressure, he's on amlodipine and Inderal and I'll just tell you on Friday, I was like, you know, "I'll see you Monday morning, but why don't you over the weekend take some Lasix?" I gave him 20 milligrams of Lasix a day with 20 milligrams of potassium, and I asked him to come in before our visit on Monday to get some labs done.
DR. CIFU: And so maybe I'll leave it there for you. What would you be thinking at this point?
DR. STERN: Oh my goodness. Well, so a lot of thoughts jumped to mind but let's try to be systematic. So he has bilateral, from what you've said, lower extremity edema. So that certainly focuses the differential diagnosis on either things that cause lower oncotic pressure or high hydrostatic pressure, permeability will be somewhat less likely in somebody who's not acutely sick with it. Amlodipine can give lower extremity edema, of course, but normally not severe--
DR. CIFU: Right.
DR. STERN: --it's normally 1 to 2+ pretibial edema and that's about all you'd see. Certainly the fact that he's cirrhotic would make you wonder if this is just the cirrhosis but you're kind of telling me he's always been controlled and now it's much worse, and that's peculiar. I would wonder about what the cause of the cirrhosis is because some of those causes also go back to other organs. So for instance, if he's an alcoholic cirrhotic, you'd wonder about alcoholic heart disease or cardiomyopathy.
DR. CIFU: Right.
DR. STERN: And if he had one of the chronic hepatitides, he could have glomerulonephritis from that. And so, I'd want to know more about the cause. To start off with, I'd probably start off with a-- And I'd also want to know about his belly exam, does he have ascites or not have ascites?
DR. CIFU: And I asked him about that and he said, no, pants all fit him well. He's a guy who works every day, so he actually puts on pants and a belt every day, everything's fine. He's not been sitting around during the pandemic wearing pajama bottoms every day.
DR. STERN: So that's a little bit surprising if it was cirrhosis, so one would have expected he'd be accumulating ascites as well, I guess?
DR. CIFU: Yeah.
DR. STERN: But I'd want to know his albumin, and I want to know his PT-PTTs, LFTs. You can have retroperitoneal lymphadenopathy that causes bilateral lower extremity edema. And he's, how old did you say? In his sixties?
DR. CIFU: He's 65.
DR. STERN: So prostate cancer can metastasize to the retroperitoneum and cause bilateral lower extremity edema but I'd probably get a brain natriuretic peptide as a screening test for heart failure. The albumin will help with our oncotic pressure. We need to know his electrolytes, his B-U-N and creatinine to start and a U-A to see if there's anything, does he have proteinuria, nephrotic syndrome, and so on. So wide array of tests to start.
DR. CIFU: Okay, so I had told you that his liver disease was from alcohol but you obviously weren't really listening--
DR. STERN: Ah!
DR. CIFU: --but, so I ordered all the tests you asked for--
DR. STERN: Okay.
DR. CIFU: --and so,
DR. CIFU: he comes to me in the office and his comprehensive metabolic panel, kidney function, liver function, normal, as it has always been actually. His INR was 1.0, his BNP was 1,824, his urinalysis was normal with no protein. And actually, let me just ask you, do you have a sense of-- I think we both know well and everybody probably knows well the idea that BNP is very good for ruling out heart failure in someone presenting with dyspnea.
DR. CIFU: Do you have any idea about test characteristics, in the setting of just edema?
DR. STERN: I don't, I've never seen that. I don't know if it's even been studied in the different-- I suspect all the studies have gathered everyone who's being evaluated rather than discriminating based on what their presenting symptom was.
DR. CIFU: Right, yeah, I was just looking it up in kind of the 15 minutes before we sat down here and couldn't find it. I'll keep searching. I guess, if anybody knows the answer to that out there in the podcast world, tweet at me with the answer and a reference, of course. So on physical exam, I will give you his vital signs first.
DR. STERN: So can I say what I would look for? Because it's probably--
DR. CIFU: Oh, sure.
DR. STERN: This is one of those times where it's incredibly important to look for things that you're looking for specifically, so--
DR. CIFU: So are you saying that you only see things that you're looking for?
DR. STERN: I think you see them, but there's a lot of data that says actually when you look specifically and with intention for things, you're more likely to find them, don't you agree?
DR. CIFU: I absolutely agree.
DR. STERN: So his vital signs would be important, you could also check his blood pressure make sure there's no pulsus paradoxus, you know, in case he had tamponade, you could check an S3 gallop and JVD are going to be to important and obviously for murmurs. That's going to be the highlight given the BNP being that high, but go ahead.
DR. CIFU: You didn't ask for the one important piece of information, so his blood pressure was 120/50.
DR. STERN: Okay.
DR. CIFU: Respiration's normal, temperature normal, pulse of 96%-- pulse ox of 96%. Would you like to know his pulse?
DR. STERN: Why not?
DR. CIFU: His pulse was 36.
DR. STERN: That's not normal.
DR. CIFU: His weight was up 12 pounds since the last time I'd seen him which was actually only about two months before and his physical exam, other than 3+ edema up to the knees was really unremarkable except for this bradycardia.
DR. STERN: So he's presenting with heart block, with heart failure?
DR. CIFU: So an EKG in the room showed third degree heart block.
DR. STERN: Oh my God.
DR. CIFU: Admitted that day, had a pacemaker that day. And interestingly was diuresed while he was in the hospital, went home off diuretics and this has been years and never recurred.
DR. STERN: So proving once again, that vital signs are vital.
DR. CIFU: Yes.
DR. STERN: Right?
DR. STERN: How could I have not asked you for the vital signs first? All of our students are going to be talking to me about this case. Can we restart again and re-record?
DR. CIFU: [chuckles]
DR. STERN: All right. So I think, having embarrassed myself, I'm now perspiring over here, can you give us five key points about diagnosing edema?
DR. CIFU: Sure and a lot of this is actually going to be restating all the things that you talked about as you went through the differential since you did such an excellent job. So point one is basically to know the pathophysiology. So edema occurs and you mentioned I think all of these, when there's increased hydrostatic pressure, capillary hydrostatic pressure, so basically something pushing from the inside out, so that's certainly what you'd see with say, heart failure or an obstruction of the vasculature.
DR. CIFU: Decreased plasma oncotic pressure, so decrease of what's pulling the fluid in, and so that's really any hypoalbuminemic state. Increased capillary permeability, that's going to be sepsis, burns, things like that, where your capillaries are leaking fluid out. Increased interstitial oncotic pressure which is pretty unusual. The only thing that I could think of that does that is myxedema, right? Where you're sort of sucking fluid out of the capillaries, and then lymphatic obstruction, there's always a small gradient of favoring the filtering of fluid from the vessels into the interstitium, and it's the lymphatics whose job it is to suck up that extra fluid.
DR. CIFU: And so if your lymphatics are obstructed, you're going to get edema.
DR. STERN: Yeah, it's interesting. I just had a patient who showed up in clinic with one leg that was severely swollen and they did an ultrasound to look for a DVT which was negative, but it was very impressive. And we did a CAT scan and he indeed had metastatic prostate cancer blocking up his lymphatics.
DR. CIFU: Yeah and I think with those so often it's unclear if it's venous congestion, right? Or lymphatic obstruction or maybe a combination of the two.
DR. STERN: Right and actually for him that's true because the venous system while not clotted, it wasn't as open as normal.
DR. CIFU: Yeah, yeah. So you're actually getting increased capillary hydrostatic pressure and decreased lymphatic drainage--
DR. STERN: Right.
DR. CIFU: --sort of a two hit effect.
DR. STERN: All right, so that's our pathophysiology. Do you have a second key point for us? [chuckles]
DR. CIFU: [chuckles] So the second key point is, even though that's the pathophysiology and it's really good to know that I think, the differential diagnosis is exactly how you looked at it, it's looking at distribution and this is really the first pivotal point kind of as you get into the differential diagnosis. So when you see bilateral lower extremity edema, or I guess, bilateral edema anywhere you're looking at a systemic cause.
DR. CIFU: So that's heart failure, liver failure, cirrhosis, kidney failure, medications. Okay? Many, many medications will as a side effect cause edema, low albumin states we talked about, and proximal vascular lymphatic obstruction as we just discussed, so maybe high enough that you're out of the unilateral obstruction and up to the bilateral obstruction.
DR. STERN: Okay.
DR. CIFU: I'm going to move on to the third key point.
DR. STERN: Go ahead, go for it.
DR. CIFU: So third key point is tests and you sort of jumped all over this. When I hear about bilateral obstruction what I think about is, I'm going to ask a bunch of questions about medications but I'm pretty much always going to test the heart, the kidney and the liver. And so I'm looking at liver function tests, I'm looking at INR, I'm looking at albumin, I'm looking at renal function and also definitely, definitely, definitely an urinalysis because I want to see proteinuria.
DR. CIFU: And then I'm usually, besides really taking my time to examine the heart much more than I would in sort of a regular office visit that I'm not really expecting to find anything, those are the times I'm really going to have the person lie down, shirt off, listening for an S3, getting them into a left lateral decubitus position, listening for murmurs. And then I'm going to think about venous insufficiency.
DR. CIFU: Right? For bilateral edema. If it's unilateral edema, I'm sort of all about what's obstructing this person. So I'm going to be thinking about maybe a D-dimer if the person's at low risk or I can't get an ultrasound the same day and then almost certainly an ultrasound unless this is localized edema that it's clearly because of an underlying arthritis or cellulitis or something like that.
DR. STERN: One of the things that's tough about that clinically is, you often see people who have edema intermittently and that day it's a little bit worse. And, you know, I have to say, I ponder blood clots more often than I'd seen them but since we can't afford to miss them, I'm always on the side of testing.
DR. CIFU: Right. And fortunately you're not doing venography, right?
DR. STERN: Right, right.
DR. CIFU: It's an ultrasound. It's fast, it's cheap, it's non-invasive--
DR. STERN: And it can save their life.
DR. CIFU: Right, it can, you can save a life.
DR. STERN: Okay. So the fourth key point?
DR. CIFU: We're up to the fourth key point. This is like the classic, you know, getting into the weeds internal medicine thing, is that pretty much every cause of edema you're going to come up with opens up an entirely 'nother differential diagnosis. Okay? So your job sort of, once you determine the cause of the edema, is to go further and figure out what's the cause of the cause of the edema. So what I mean by that is, if you find out like, oh, there's a cardiac cause to this edema.
DR. CIFU: Well, is it HFrEF, is it HFpEF? Is it constrictive cardiac disease? Is it pulmonary hypertension? And then each of those has its own differential diagnosis. Right? You mentioned cirrhosis, whatever, you know that's an end-stage liver disease. What caused that? Maybe it doesn't matter for cirrhosis but for reasons you pointed out, it may.
DR. CIFU: Certainly kidney disease, right? Every cause of nephrotic syndrome will cause edema. So you got to know that.
DR. STERN: Are you going to walk us through all the causes of nephrotic syndrome and glomerulonephritis? I was kind of hoping for that.
DR. CIFU: I'm sure you have them written on your walls in your office.
DR. STERN: [chuckles]
DR. CIFU: And then the fifth and final key point is, don't forget about medications. I am amazed at how often I see patients with edema related to medications. And I don't think it's missed commonly, but I think maybe it often comes up a little bit too late in the evaluation. So calcium channel blockers for me are, you know-- A lot of people are on calcium channel blockers, these days, mostly amlodipine. And like all side effects, it's complicated, often it's right away, but you can have someone who's been on amlodipine for four years and then their edema gets worse probably because they've got a little bit more venous insufficiency than they used to, and now it's become important.
DR. CIFU: Hydralazine, minoxidil as less commonly used anti-hypertensives, just about any hormone that we use, estrogen, progesterone, testosterone, glucocorticoids all do it. I'm sure your favorite, Scott is NSAIDs because you always seem to be all about every side effect of NSAIDs, and then thiazolidinediones which we don't use that much for diabetes, one of the reasons is, because they cause a lot of edema, and so we've sort of stopped using those.
DR. STERN: I guess, I'm all over NSAIDs because I get edema when I take them which is really irritating.
DR. CIFU: Yeah.
DR. STERN: Do you remember? I think we are probably the only two people old enough on the podcast to remember minoxidil's use. I mean it used to be used a lot for renal failure.
DR. CIFU: Right, right.
DR. STERN: And wow, people got lot of edema on minoxidil.
DR. CIFU: And I think out of my whole patient panel of whatever, 800-900 patients I think I have two patients on it--
DR. STERN: And you know it's funny, it's Rogaine, right? So people may not know on the podcast that minoxidil is the same substance that's used to make your hair grow and the reason that was discovered actually is when we had people on minoxidil, they had tremendous hair growth down their forehead and all over and it was really quite a remarkable-- That's how somebody figured out, hey, maybe if we just make this a salve, it will help.
DR. STERN: I don't think it's helping so much. Okay. So is there anything else to say about our case? How did he do? What happened?
DR. CIFU: I was going to say usually we go back to the case and there's nothing more to say. Person did terrifically, our skilled electrophysiology people were all over it. I think left the hospital either 24 hours or 48 hours later. And this is one of those things that now just lives on a problem list and I think has actually already got his pacemaker battery replaced at this point.
DR. STERN: Your teeth must have fallen out when you saw his heart rate was 36. Who would think that he calls you up with some swelling, oh, come in on Monday. I don't actually know that your pulse is 36. That's unbelievable.
DR. CIFU: What I remember is actually immediately getting into an argument about, you need to come into the hospital. "I don't need to come into the hospital I just have swelling." I was like, you need to come to the hospital.
DR. STERN: He's lucky his lower pacemakers were working.
DR. CIFU: Yes.
DR. STERN: Okay.
DR. STERN: Let's go on now to fingerprints, common misconceptions, pet peeves and other random pearls of knowledge, Adam--
DR. CIFU: Okay.
DR. STERN: --got some fingerprints?
DR. CIFU: Fingerprints, so this is a little bit off the subject but not really, caput medusae. So those are the large dilated veins that one gets around the umbilicus. So if you look at those as a test for cirrhosis, the likelihood ratio is 9.5, okay? So if you're seeing that in a patient who, I don't know, has edema, has a bloated belly, you should be thinking cirrhosis. And as I prepared for this, I learned a new eponym, I'm going to pronounce this wrong, I think it's the Cruveilhier-Baumgarten murmur.
DR. CIFU: Have you ever heard that?
DR. STERN: Wow!
DR. STERN: Oh, the well-known Cruveilhier-bada-badah. What is that?
DR. CIFU: So that is a venous hum over the umbilicus.
DR. STERN: There you go.
DR. CIFU: [chuckles]
DR. CIFU: Unimportant.
DR. STERN: Okay.
DR. CIFU: Move on.
DR. STERN: There you go.
DR. STERN: Okay, caput medusae, Medusa's Head. All right, so while we're on symptoms or signs of some of the diseases that cause edema of course heart failure, S3 gallop and JVD are very specific with likelihood ratios of 11 and 5.1 and I just want to emphasize, you got to get used to looking for jugular venous distention putting the person in the right position, really looking at the side of the neck for a minute. There's many good YouTube videos out there if you haven't looked at them, because it's very helpful.
DR. STERN: So, I look for those routinely.
DR. CIFU: I'd add the S3, too. You got to listen for an S3 because if you just do a quick listen, often you'll miss it. I almost feel it as like a vibration rather than a real heart sound.
DR. STERN: It's true.
DR. STERN: It's almost something you feel.
DR. CIFU: Yeah.
DR. STERN: It's a weird comment, but it's true. All right, misconceptions.
DR. CIFU: I think my misconception is that diuretics work for venous stasis disease, or maybe I should say that diuretics are the treatment for venous stasis disease. They're not, the way you help venous stasis disease is you have people wear compression stockings, you have people elevate their legs when they're at rest, you have people exercise so they're working the muscles there which are helping to push the fluid back and venous stasis disease often comes I think of the valves in the veins which help that fluid to only move in one direction as the muscles in the leg pump.
DR. CIFU: If you remember from anatomy, those valves are like tissue paper thin, and as we get older, those just sort of poop out, and so they need a little bit of help and the help is usually from external compression. And if you want to use a little bit of diuretic to sort of help out the compression stockings, great, but they're not going to do it alone.
DR. STERN: But who wants to wear a compression stocking? So I may have this problem, Dr. Cifu, and I don't want to be walking around in compression stockings.
DR. CIFU: Yeah, it's a tough life.
DR. STERN: All right. So my misconception is people often expect DVTs to present in a very, kind of classic way with a painful cord and pain and swelling, and the reality is patients often only have one of those multiple things, as a matter of fact only 40% of patients who have DVT actually have pain. They might just be swollen on that side and they don't even have to have edema. So 80% of people with a DVT have edema but 20% don't.
DR. STERN: So essentially what that means is anybody who comes in with any complaints about the calf, you have to think about DVT. "Oh, it's hurting." It doesn't matter whether it is edema or not, get the ultrasound or a D-dimer. "Oh, I have pain," and you don't see anything just do it because it's tricky business.
DR. CIFU: That is a great point. That is a great point. And I think the nice thing now is with D-dimer-- because you will risk stratify people, it's not like we're saying, everybody who ever comes in with trace edema on one side needs an ultrasound.
DR. STERN: Agreed.
DR. CIFU: You risk ratify, you figure out, do you need to test at all? Do you need a D-dimer? Do you need ultrasound? And it's probably worth pointing out which I can't believe we haven't talked about, so when people get edema, it's always worse on the left, like slight bilateral lower extremity edema because the circulation has to sort of cross further over, so generally, left a little bit greater than right, usually it's going to be asymmetric.
DR. STERN: That's really interesting. Huh!
DR. CIFU: That's a great point, Scott. I would not have thought about that but that's great. Pet peeves. [chuckles] This one goes way back for me. The ability to assuredly rule in or rule out ascites based on the physical exam. Our physical exam is not good for ascites. And I think as our nation gets more and more obese, the test characteristics of our exam probably get worse and worse.
DR. CIFU: I point this out because a thousand years ago when I was a resident, I consulted a general surgeon, this is what we did at the time for a G-tube on a patient. And the surgeon was like, "I am not doing a G-tube on this patient without an ultrasound because this person has ascites," and spelled out ascites in the chart for me so I could see it. And I was so happy when the ultrasound came back negative and I could write in the chart, this patient does not have ascites and I spelled out ascites, it was quite mature of me.
DR. STERN: [chuckles] Oh yes, bring us back to residency. Okay. My pet peeve is really, I often hear when people present cases of edema that they actually haven't taken the steps to figure out if it's unilateral or bilateral, and so just as we've already mentioned, use that paradigm, it's very helpful for at least a start.
DR. CIFU: That's great, that's sort of like medications, you're probably going to get to the right place but it's going to take a whole lot longer. You'll probably put the patient through more tests, you'll probably spend more money.
DR. STERN: All right, clinical pearls.
DR. CIFU: Clinical pearls. Don't just look for the legs when you're looking for edema. I think we've been very focused on lower extremity edema but edema can be anywhere, right? And your differential is going to change if the person has anasarca rather than lower extremity edema. And especially in the hospital, many people, you'll put them to bed for a day and their low extremity edema will go away but they have tons of sacral edema, right?
DR. CIFU: And so you got to make sure that, especially for me it's when you're examining people in bed, check their legs, also get behind them check their lower back, check their pelvic area, check their belly, see if they have a fluid wave, listen to their lungs, you're looking for extra fluid everywhere.
DR. STERN: Now that you're on it, we should probably mention the few other places people occasionally complain of localized edema. So if you see upper extremity edema, especially unilateral, you should always be worried, something's really wrong, typically an upper extremity DVT. You want to know if they had a catheter in or not, but you need to look, and the other one that's tricky I've found is superior vena cava syndrome. So when you obstruct your superior vena cava, the classic syndrome is people are plethoric and they're swollen.
DR. STERN: But if you don't know that person, I have to say all the people I've seen with SVC syndrome, the family complained that they were swollen, and I looked at the person and said, they look okay to me.
DR. CIFU: Right.
DR. STERN: So if a family says the face is swollen, then you need to take that seriously and think about that.
DR. CIFU: PLE-thoric, I say.
DR. STERN: Ple-THO-ric.
DR. CIFU: Okay.
DR. STERN: What did I say?
DR. CIFU: You said ple-THO-ric, I say PLE-thoric.
DR. STERN: Oh, well potato, patato.
DR. CIFU: Also where I thought you were going to go is, there is a thing like periorbital edema--
DR. STERN: Yeah.
DR. CIFU: --foreskin edema which I often think of as part of angioedema that you see when you see that sort of really delicate soft tissue without more diffuse edema.
DR. STERN: Although penile edema can be prostate cancer. So when you get edema in the genitals you have to be very concerned about an obstruction of the lymphatics again.
DR. CIFU: True.
DR. STERN: All right.
DR. STERN: So my clinical pearl was a little bit more about management. We don't talk much about management but one of the things that comes up all the time in the primary care group is using diuretics for heart failure. And you have to be willing to tolerate a little bit of a bump in the B-U-N and creatinine to get somebody euvolemic, that's okay, you know, we're really aiming to get them. And you have to look at whether they have edema, JVD, S3 gallop, maybe even a chest X-ray and decide about how to push it but we're not really focusing on therapy.
DR. CIFU: Yeah, and also that's kind of the goal. I mean, often when you see people come in and if they've got a B-U-N and creatinine of 10 and 1, you're like, I'm not doing enough here.
DR. STERN: Right. It's true.
DR. CIFU: Okay.
DR. STERN: Right.
DR. CIFU: My last pearl, I think is more of, I don't know, it's like cocktail party conversation. So it takes about three liters of extra fluid to cause edema. Before that, I guess you've got a lot of interstitium that you can put away fluid before you actually start to swell. And remember that a liter is a kilogram. So three liters of fluid, when you start to see edema that's six and a half extra pounds of fluid.
DR. CIFU: That's a lot and it helps though, because you can tell patients when they come in with edema and you can say, "We've got six pounds of fluid we got to take off you."
DR. STERN: So this way I'm just going to eat Chinese food, like it's six pounds of water. [both chuckle]
DR. STERN: Well, that's impressive.
DR. CIFU: So we hope you found this episode of the Symptom to Diagnosis podcast useful and a bit enjoyable. As a reminder, our textbook, Symptom to Diagnosis: An Evidence-Based Guide takes a much deeper dive into how to think about and reason through the diagnosis of medical presentations. The book is available in print, on your handheld device and in a fully searchable mode via the Access Medicine website available worldwide from McGraw Hill.
DR. CIFU: The music for this, the STD podcast is courtesy of Dr. Maylyn Martinez.
DR. STERN: Thank you. [upbeat outro music] [upbeat outro music]