Hyponatraemia

Speaker 1 Med conversations. Speaker 2 Hello, thanks for listening to Med conversations. I'm back and I'm here with Scott and today we're going to be talking about hyponatremia. Speaker 1 So this is a super common problem on the wall. Probably the most common electrolyte disturbance. So Speaker 2 pretty common thing you're ever going to Speaker 1 see, mmm, most common illness even maybe Speaker 2 and sodium is one of the most common cations. Speaker 1 In the blood. Thanks for that because it's a great day. So going straight into it. So back. What's a normal range of sodium in the blood? Speaker 2 So normal range is about 135 to 140 5. Speaker 1 And the key thing there is that in hyponatremia, it's usually problem of too much water, not insufficient salt. So you've got probably about the same amount of salt in a lot of the cases but you've got way too much water. So your concentration of salt is low. Yeah and so So hyponatremia is, as we said, one of the most common things you say about, 60% of in patients have some kind of hypernatremia regardless of what the cause of their admission is, and I think it matters because it kills people who keeps people in hospital longer and like we said we see it all the time so we figured we might as well talk about it. So back I think you've done your homework. What are we going to talk about today? Speaker 2 Yeah so we're going to go through the physiology of sodium handling will talk about acute versus chronic which is a question that I think we always have to ask ourselves when it comes to hyponatremia clinical presentation, approach to finding a cause and then we'll discuss Ward based management and how to avoid the pitfalls of overcorrection. Speaker 1 Mmm, sounds riveting. Let's go hop straight in. Speaker 2 So what's the deal you mentioned before that? The problem is too. Much water and not insufficient salt. Speaker 1 Yeah, so if you remember back to kind of high school biology or first-year med school in your blood, you've got a concentration of different solutes and that's what determines its tonicity and that's what drives osmosis across all the different membranes that are going on. So sodium is the most important cation. So the most important positively charged ion in your blood so it's a biggest contributor to that concentration there. And so there's kind of four key hormones that regulate your sodium in your water in your blood. So you know what they are back. Speaker 2 I do. Thanks for asking so their main one is a th which is antidiuretic hormone and I think the thing that gets really confusing here is that it's got lots of different names. So we're going to be calling it a th today, but the other names are a VP or Speaker 1 vasopressin. That is really Speaker 2 confusing. So that's how my number one and the job of the ADH, which I'll talk about it in more detail. Tailing of moment promotes water reabsorption in the kidney. That's the main thing that one does and then there's aldosterone. Speaker 1 So, so ADH is for water. Aldosterone is also called salt retaining hormone because it's about sodium reabsorption and remembering that once you reabsorb sodium, you also reabsorb water with it because water will follow sodium in your kind of Osmosis osmotic, gradients Speaker 2 and then you got your atrial, natriuretic peptide and brain naturally peptide. What's the role of Speaker 1 So they produced by cells in the heart muscle in response to being stretched so the kind of their natural peptide. So instead of being to natural resource means excretion of salt. So they're hormones that your body makes when the heart feels like it's being stretched too much basically. So it says that you've got too much, intravascular volume so your body makes this hormone and it helps push out So and with it volume because the waterfall is the salt. Speaker 2 Yeah. So and like we said the main the main thing controlling water is the ADH. So just to give it a really brief overview of, what a th is all about. So it's secreted from the posterior pituitary and that the things that stimulate it, I'm predominantly the serum osmolality. So if you osmolality in your blood gets above about 285, then in response of that in response to that, sorry the the ADH will be secreted. A couple of other things that influence at our the blood volume and the blood pressure to a lesser extent and even some things like nausea and pain can stimulate the release of Speaker 1 ADH. Hmm and what a DH. So what are th does is it increases the amount of aquaporins in your collecting duct which stops the excretion of Speaker 2 water. Yeah so you can set these in and then the water stays in the body. So in patients who have a low effective Well, circulating blood volume whatever the cause of that is ADH, release is physiological and it helps to pump up the circulating volume. So some of the things that can cause low effective circulating volume are hypovolemia like someone who's really dehydrated or edematous conditions like heart failure, where there is intravascular depletion so it's hemodynamically appropriate in these situations to release a, th the syndrome of inappropriate ADH is when the release of ADH is happening, but it is not hemodynamically appropriate. So when the ADH is in completely suppressed, despite there being a low plasma Speaker 1 tonicity, so is that really simply basically your secreting too much, a DH in siadh when you shouldn't be. Yeah. Okay. So an approach to hyponatremia Scott. Where do you start? So first, you want to get two things out of the way. So we want to know whether it's a hypotonic hyponatremia. So as we said, your sodium is your main cut iron in your blood, which is kind of producing its tiny City. So it's concentration of solute in the blood. So if your sodium is low, your overall concentration of solute in your blood should be low. So that would be in a hypotonic hyponatremia. So if it's an isotonic or a hypertonic hypernatremia Mia. Then we put it in another category and the other thing to think about is whether it's a pseudo, hypernatremia Sobek what's a pseudo Speaker 2 hypernatremia. So pseudo, hypernatremia is looking at whether there's a measurement issue, that's making it appear to be hyponatremia hyponatremic even when it's not. So in really extreme hyperlipidemia, not just your average person who's got slightly high LDL but Extreme hyperlipidemia where you do a blood sample and it looks like a strawberry milkshake. The blood when looked at in a lab seems to have less sodium for that amount of volume. So it looks like it's hyponatremic. But in the actual rate of serum that's floating around those globules of fat, the concentration of sodium is in fact normal. So you get around that by doing a blood gas, hyper protein emia does the same thing. So, high protein States might be like, multiple myeloma or if you have too much bulk Mass gain protein bars. Mmm. Then Speaker 1 back after a marathon, On Speaker 2 yeah absolutely. No, they're disgusting. So high lipids and high protein and really high can make it look like you have hyponatremia and that's pseudo hypernatremia. Another thing that gets called pseudo hypernatremia, that strictly isn't is hyperglycemic States. So the way that works all Scott, do you do want to explain it now, okay? So the way that is Jackie's, it. He's osmotically active. So in patients who have very, very high blood sugars, like blood sugar's of 5060, the the water is being drawn out of the cells via osmosis because there's so much sugar floating around there in the ocean around the cells and because all that water is coming out into the serum, the sodium is being diluted. So what you need to do there to get a true sodium measurement, is to get your med Calc app on your phone and correct the sodium level for the Speaker 1 glucose. So If I understand that correctly, even though your sodium is lower because glucose is doing the same thing that that extra sodium would be doing. Anyway that's a new cities are saying you don't really care. Exactly. Okay, cool. See, I could explain it at the end. Speaker 2 All right, so then I thought we could have a look at what the symptoms are of hyponatremia. And this is pretty boring because they're pretty vague. Speaker 1 I'll turn dacians pretty fun. Its particular symptom. So yeah, so I guess like big said, there's kind of two kind of categories of symptoms. So the first ones are these really vague set of symptoms that people can get. And these are things like fatigue, nausea, dizziness gait disturbance bit of confusion, muscle cramps. I think a lot of kind of old ladies being admitted into a gen Ed, water going to have some combination of those symptoms. And then you've got your really kind of severe symptoms. So, that's when people find a job, their GCSE become at, under, they can have seizures, go into Comas, and they're the ones that we obviously really worried Speaker 2 about ya. So the end point there's usually respira tree arrest and these are the kind of symptoms that happen when the sodium is very low like less than 120. And generally only in a cute. So what actually is a cute, what's the time frame, what's the cutoff there Speaker 1 and it's 42 hours, is it 42 42 48 going off the Mayan calendar. Speaker 2 So they generally and generally we say 48 hours is the cutoff but it's sort of 24 to 48 hours. And when you have a patient who comes in and has a measured sodium that's low you can't always Ways. Tell whether it's acute or chronic. Unless the history is really compelling. Like they've just run a marathon today and they've had seven liters of water, or unless they actually had a blood test yesterday. And if you don't know, then you just need to assume that it's chronic. Speaker 1 Yeah, because as we'll talk about later, it's the important thing in chronic hyponatremia. If you take nothing else out of this is not to correct it too quickly. Speaker 2 Mmm. So, I think that the reason for that is best understood by just understanding the physiology in general. So if you've got an acute reduction in your sodium, then you're also acutely reducing the osmolality. And as with any other situation where this happens in the body that can create a gradient of fluid. So the if they're low, Osmolality in the serum, water goes into the cells and makes them swell. So it's causing swelling of the brain cells which causes cerebral edema. But then if the sodium isn't acutely reduced, if it's a gradual reduction in sodium, or if it's been reduced for over that 24 to 48 hours, then there's an Adaptive response where the brain cells instead of just swelling, they send some of their solutes out of the cells into the surrounding fluid. And into the hyperosmolar, see they float these extra solutes and then that means that cerebral edema the swelling of those cells. Doesn't care. Speaker 1 Mmm. So they like turn up the temperature of the tonicity bath that they're in. Yeah, that's a really shitty. Speaker 2 And then if you want to do that, if you reverse the hyponatremia, then those processes are also reversed. First, but then, I think the thing that's really interesting here and really terrifying is that those adaptive mechanisms that happen, those brain solutes that were lost as part of the Adaptive mechanism to reduce swelling. I take him in and take them back in more slowly slowly than they were initially lost. So if you're fixing the problem, if you're fixing the hyponatremia, then the brain takes longer to undo the thing that it did to prevent the edema and that basically causes all hell will break loose And you can get something called osmotic demyelination syndrome, which used to be called Central pontine myelinolysis. Speaker 1 So basically it kills people and that's the whole reason we care about sodium correction. You need to be really careful. You don't give them too much or you them any hypertonic saline and lets you speak to someone very qualified in the task as back will be shortly. Speaker 2 Yes. Oh so I think this is this is really the main, the main Crux of all of this, that hyponatremia can be really bad. But Fixing hyponatremia too quickly can be really, really bad. So what it causes is severe neurological. Deficits that can happen a few days down the track within last forever. Speaker 1 All right, so to summarize all the stuff we've been saying. So far, you've got a few different hormones in your body that control yourself and your water together. But antidiuretic hormone ADH also known as a VP of vasopressin is the most important one for specifically regulating water. Rather than water together with sodium and back. What are the three kind of first questions when you first find a patient with Speaker 2 hypernatremia? So, the first one is, could this be a pseudo hyponatremia or a hypotonic hyponatremia? So, I'm thinking about, what's the blood sugar? What's the protein? And what are the lipids? Speaker 1 And is the patient's symptomatic to have some of those vague symptoms of confusion or GE headache or they actively seizing? Are they seizing in front of you? Yeah. And it will be quite obvious. Speaker 2 And then, the third question is, Is this acute or chronic with 48 Hours being the cut off? And so I think once you know these things then you can start looking at what could the cause be. Speaker 1 So now we get into these wonderfully, long flowcharts. I think there's one in up to date which you could probably fit across about six kind of A4 Pages stuck together. But, and you can kind of choose which flow chart. You like, for kind of looking at the different causes of hyponatremia but they're actually pretty useful because, I mean, you can actually just sit there with one, look it up on your computer or whatever. Ever and you can look down through all the different causes with all the different blood results and good results and decide. Speaker 2 Yeah. So I think this is where the robots are going to be helping us out a lot hyponatremia, is something that can be very algorithmic, so I think what is best to do is actually to pick your flowchart that suits you. So if you're a med student, not so important. But if you're an intern or resident, if you already in the hospital, if you have your phone with you, now look up European journal of clinical investigation hyponatremia and there's a wonderful flow chart there. There's one Non Life in the Fast Lane. That's great. And there's one on up-to-date and we're going to be talking about a bit of a mash-up of all of those three flowcharts. But when you physically on the ward, just going through, these algorithms can be immensely helpful Speaker 1 from European General. One is three different colors. Speaker 2 Yeah, the color coding is really nice. Speaker 1 Very friendly and kind of colorful. So what are you up to approach? So when you when a patient first comes in with hypernatremia, one of the first things you should do is you should try and get a ped serum and urine osmolality and sodium. So when the patient comes in to Edie if the Ed refers to you over the phone or if you're maybe the intern or resident admitting the patient in Ed before you give fluids, you should make sure you get a set of blood center off. At the same time that the patient has a way. Speaker 2 Yeah, and this sounds like it would be pretty easy to do, but it's extremely hard and it never happens. So what you need to write on the slip is one slip for serum and you're asking for osmolality and UEC, and then another slip for urine and again, asking for osmolality and sodium. I staple them together. I tell the patient, I tell the nurse, I tell anyone who's going to listen because it's very hard to make sure that this happens before anything else is given to the patient. So you do that number one. Number two, you want to look to see if there are any possibly offending. Medication. So any medications that might be causing hyponatremia and stop them. And then number three, you need to do a fluid review. If the patient is dry, give them a normal sale in that will usually fix the problem. If they're edematous treat the underlying cause treat the heart failure, treat the renal failure, or if they're euvolemic or you're not sure what their fluid status is keep listening, Speaker 1 gets more complicated just to make it even more fun. So as we're talking about, Got this hypertonic or isotonic hyponatremia. And that's what we're not going to talk too much about today but there were some of those causes like really high sugars really high proteins, really high lipids in the blood that give you those other causes. And then we've got hypotonic hyponatremia, which is what we'll be talking about. Yes, the podcast Speaker 2 and so to be clear. So what we're talking about now is what are the causes of hyponatremia and specifically what are the causes of hypotonic hyponatremia. The number one hypovolemic hypovolemia. So that would be the usual things that can cause hypervolemia. So your dehydration post-surgery post, massive bleed, diarrhea, nausea vomiting, that kind Speaker 1 of thing, seven different abdominal tubes, like all random stuff. Yep. And next is hypervolemic. So basically heart failure, liver failure, kidney failure. So on the ward, probably, although kind of oldies with Mi heart failure, might be the most common cause of a hyponatremia. Damn, it boy Speaker 2 and then there's the euvolemic ones. So usually this is sath or syndrome of inappropriate ADH, where there's too much of the ADH and this can lead to high urinary sodium, which is inappropriate. The second one would be self-induced water intoxication. So, something like primary polydipsia. This is the person who's drinking liters and liters of water every day or my favorite. If you had a beer pot of mania Speaker 1 have and cousin Victoria we call small beer spots. I always thought It was because they drank too many pots. I thought to, you know, kind of comes out from some Greek word, for River pot or something. There you go. It's not because we call beers pots and Victoria be a Potter Mania. Yeah. Speaker 2 So so the story with that one is that you're you're drinking a lots of fluid without much salt and usually without much other nutrition in the diet and similar to, that is the tea and toast diet, which again all the oldies are on as well, which is a very low solute. Hi, Dad. It water diet, Speaker 1 so you're drinking too much volume. Past the maximal, kind of dilutional capacity of your kidneys. Basically, Speaker 2 that's it. And then some rare causes to think about our adrenal insufficiency and hypothyroidism. So they need to make it onto your blood slips in. That's enough of a theory. So we're just dive into some cases now. Speaker 1 So, back, tell me about Lena Speaker 2 load. Lena low is a 76 year old lady who's been brought in by ambulance after an Unwitnessed fall found after a local teenage drone. Operator found her when flying over her backyard with a video camera. And a, I had a patient with this presenting. Speaker 1 Complaint is just a classic, really? Common kind of sit Speaker 2 scenario. Oh, welcome to the 21st century so Lionel. Oh, she's been found in a backyard. She's fine. Her past medical history is a bit boring. She's got hypertension. Gout atrial fibrillation initial Bloods are back. She's got a blood sugar of 8 which is Potent because we're checking to see if there's an extremely high sugar, that might be causing her sodium to be low. And there's not her FPE is unremarkable and she has a sodium of 128. So remembering that the lower limit of normal is 135 her renal functions normal and she's had a normal CT brain. So now we're going to go through that approach again. So Scott what was the first thing that we're looking at? Speaker 1 So we're checking whether it's a real hyponatremia. So I hypo Tonic happen. A trivia or whether it's a pseudo hypernatremia. Speaker 2 Yeah. So we've mentioned the, their blood sugar is fine. You have a look at a liver function tests, there's no abnormal protein, they're just doesn't have a history of multiple myeloma, her life looks normal. And there's no known extreme hyperlipidemia in her history. So we think that this is probably going to be your stock standard hypotonic hyponatremia if she symptomatic or not. Well, I guess this is something for debate. She Don't have any seizures. Doesn't have an altered, conscious state, but she's come in after a fall and Falls can be much more common in patients who have chronic hyponatremia. Speaker 1 So possibly, mmm. So and is it acute or chronic bit hard to tell? But yeah, I guess we don't really know. It depends whether the hypernatremia was kind of an underlying cause for a full or may be secondary to the full. She's had some dehydration or something else which is cause that hyponatremia. Speaker 2 Yeah. But I think the really important Point here is that you don't know, so you don't say that if you're going to guess something, you guess that it's chronic and this is a good thing that any intern can do is call up the GP and find out when their last blood test was if they happen to have had a blood test. Yesterday and it was normal. Then you know it's a cute and you're going to manage it in a very different way. So the cut off again, 48 hours and we are going to assume that this is chronic because we don't know that it's a good. Speaker 1 So next will be thinking about the cause and that'll probably be once we start getting some results back and checking, what treatment we do. Speaker 2 Yeah. So you've sent off your pad serum and urine osmolality and sodium before you did anything else and then you got to take a history. So the important bits on the history apart from getting a solid. Ask medical history, like you always would and getting a list of their medications or mentioned, she's got hypertension, gout and atrial fibrillation. Her medications are atorvastatin paracetamol Hydrochlorothiazide and allopurinol Speaker 1 allopurinol urinal. Yes. A Speaker 2 so I always like to get a good history right there fluid intake to figure out. If they might have some primary polydipsia alcohol. Use with their diet is like, so she doesn't have anything exciting on the history of a fluid intake and then the next thing you need to do is a fluid review and she's euvolemic. So is there anything that you've heard so far? Scott that's already pointing towards a possible Speaker 1 cause. Yeah well I think the big thing that sticks out there is Hydrochlorothiazide. So thiazide diuretics one of the most important causes of drug-induced hyponatremia. Speaker 2 Hmm and they're gone it's almost it is the most common cause that we say Heads of offending medications. So while you're waiting to get the results of that ped serum and urine, just you cross off the thighs. Ides. So I guess first had it had a size that's actually work. Why do they cause hyponatremia? Speaker 1 So those legs work at the distal convoluted tubule by blocking the thiazide sensitive NaCl, co-transporter. So that stops reabsorption of sodium and chloride from the distal convoluted tubule back. Back into the renal interstitium, and back into the blood. So that means you're stopping that reabsorption so your secreting more of your sodium, more of Speaker 2 your water and that and and that can also help to stimulate thirst. And so it's multifactorial but as I direct the most common, but other diuretics like in Daffy, amide, amiloride and even Loop Diuretics a cruiser might can contribute to hyponatremia. If patients are on these medications, it's really hard to interpret a osmolality and interpret the urine. So a good idea to just stop them and see how the patient goes. You know, the other most common medications that can cause hypernatremia other things to look out for on a drug chart. Speaker 1 So apart from thiazide diuretics, especially you want to think about psychotropics. Speaker 2 Yeah. So any other kind of brain drugs? So it's antidepressants like ssris would be gone, carbamazepine the other anti-epileptics and some of the antipsychotic drugs. Speaker 1 Some other drugs that occasionally can cause hypernatremia Omeprazole, and ppis, NSAIDs cyclophosphamide, and haloperidol and amitriptyline which also psychotropics. Speaker 2 Okay, so we got this Lena low, she's lying in a field which has been brought in from being lying in the field after the kid with the Drone found her, which is definitely illegal. Speaker 1 But what was he doing? Well, is he looking for with that drone? Speaker 2 I don't know. I didn't take the history from him. I mean, I'm probably not not protecting confidentiality of this Speaker 1 Michael Kidd very well, but probably reconnaissance, nothing for like fun witness Falls. I definitely was trying to Speaker 2 do. This is the gem in the home Speaker 1 service. This joining the home, Speaker 2 Okay, so we've got the Bloods back. Now serum sodium is 128, so it's pretty low. Not terrible urine. Sodium is 48, which is high Serum. Osmolality is high at 250 and the urine osmolality is lower than that at 220, but we already said she's on a thiazide. So all these numbers, don't really mean a lot because it's difficult to interpret. She doesn't have any whirring symptoms and it's not less than 120. So we don't need to jump into action straight away with It'd be guns and we're pretty sure that the cause of this is thiazide. So we've talked a lot about try not to over correct too quickly. So what is the goal? How how do you want this sodium looking in the next 24 hours Speaker 1 so you don't want to change it by more than 4 to 8 million miles per 24 hour period. So you want to just slowly bring a sodium back Speaker 2 up? Yeah, so what we'll do what we did with Lionel o is stop Turtle names. Have been changed. Stopped her hydrochlorothiazide. Sighs. I'd and change it to another anti-hypertensive medication. And then, the next day as sodium increased from 128 to 130. And then the next day to 133, and she was discharged home with a normal sodium of 135, she got a blood slip to check again with the GP in a week because you want to just keep a close eye on things. Speaker 1 Hmm. And the Drone check dated Speaker 2 post-discharge as is the standard of care because yeah. Speaker 1 So case two that survives a bit more Maria, mendilow was a previously. Well, 52 year old who presented with aspiration pneumonia following consumption of a needle, containing Australian strawberry, very topical for the next bout four days. I'm sure. So on the initial testing, you get back a normal. You and me apart from a sodium of 125 and a BSL of 5. So what's your steps again back? What are you looking at first? So first, I've made sure that the blood sugar is normal, Speaker 2 Lfts aren't showing any extremes of progeny Mia and she doesn't have any extreme hyperlipidemia. So we're going to say this is probably a hypertonic hyponatremia and continue on our algorithm. She's asymptomatic. That was another important thing to check and whether it's acute or chronic. In this case, we actually know because this patient who had been previously, well, had gone to a GP yesterday morning and had a blood test yesterday morning, that showed a normal sodium. So it's dropped down in just 24 hours. Our next step is figuring out what the cause is. Speaker 1 And what should we do to treat it? So you send off as paired serum and urine osmolality and sodium. And you take a history and she's not in any regular medications, no past history. She's got, she was after being unwell for two days who GP told her to drink lots of water and knowing that everyone already needs to drink 1.5 liters of water a day. And she thought she would drink four times that and try and drink six liters of water a day. So she's been very poly Urich. Speaker 2 Yeah. When you do a fluid review and because she's got well functioning kidneys in general, she's you've already Speaker 1 Make. And by the way, there's no evidence behind drinking 1.5 liters of water a day. I think some kind of advertising company, just picked up on that and people started thinking, the doctors wanted people to do that. This is little little sidenote little Asterix. Speaker 2 Yeah, I joined a gym once and I got told that I should try to drink five liters of water a day five. That's what the gym guy told me. Speaker 1 Well, that's that's dangerous. It's dangerous doing exercises. Well, that's really Speaker 2 dangerous anyway. So this lady has a serum sodium of 125, so that's low. SLI. She's got a urine sodium of 10 which is really low. It's very dilute Serum. Osmolality is 290, but urine osmolality is just a tea so she's basically just peeing out water. It's a cute not chronic so less than 48 hours, she's asymptomatic. So knowing all those things, what's your management Speaker 1 so fluid restricts. So it looks like she's drinking water higher than her, kidneys maximal capacity to dilute who your own. So if you just restrict a fluid and stop the water, Coming in, then it should get better. Yeah, so because it's a cute, we have a very low risk of cerebral edema from Rapid correction. So it's reasonable to aim for in excess, even of 10, million miles in 24 hours. So, you put it on a one letter, fluid restriction, check above the next day and it's 135. So it's these patients who improved extremely quickly. So you discharge it home the next day and get a follow up with the GP Joan check day for you know standard they too. Are they to sorry big guy? Let's follow guidelines here. Yeah, so these cases have been a bit kind of garden-variety. What if you had a patient came in really unwell. So a patient is under door is seizing or something like that. So what what's the first thing you do? As an ed resident back? Speaker 2 Already rage Speaker 1 Endocrinology you don't just whack in some hypertonic Speaker 2 saline. No. So you want to you want to get off that paired urine and serum and the indications. I think for an urgent correction and definitely an Endocrinology. Referral would be a sodium of less than 120 or cerebral symptoms. So that's things like a coma or seizure stuff that you're not going to miss and your target. When you're when you're try to correct, these should be no higher than 120. So usually you're only wanting to increase it by three or four. Speaker 1 Yeah and I think that's probably a good learning point around my kind of when Endo cares. So if it's three in the morning and your patient is on a thiazide diuretic and has a bit of heart failure and has a sodium of 129, you could probably wait a couple of days before you call in do, or maybe not even call in. Do if you've got a clear cause of your hypernatremia, so we're not going to talk about hypertonic saline because I think it's really important to remember, like we said before that, you don't want to cause any harm so you probably shouldn't go around trying to Correct things really acutely. It should definitely be done in ICU or in discussion with in do. Speaker 2 Hmm. And then there are a few other options for correction that we won't go into too much, but vasopressin receptor antagonist. So, this is your Connie of Upton and 12 actin. Their New Kids on the Block. We've got them approved in Australia, but I don't think they're on the PBS yet. But I think the main thing to know is that whatever route you choose to correct hypernatremia, if you go too far, which people do all the time, it's really easy to To overcorrect. You can undo it pretty easily by giving some i.v. dextrose. Or if you get some specialist, endocrine advice, you can give ddavp. So essentially that's just giving Speaker 1 a th-there's a general tip with management that kind of 428 mmol per 24 hours is actually pretty easy to overshoot so just be pretty conservative in general with hey you try and correct people. So case for Headley Heath is very little say it right here, this Brewery here. This Bree. Tell me about hit Speaker 2 lie. So headley's an 85 year old who has palpitations in the setting of learning that Australia has just rotated on to its sixth prime minister in 10 Speaker 1 years for topical episode. This one. Totally cool. Yeah, Speaker 2 yeah, in September 2018, his sodium is 128. So we're going to go through the usual things. I'm not going to labor it too much, but we've checked, he's sugars, and he's proteins and everything's all all normal. He is asymptomatic. This is chronic. This is very chronic actually. So you've called up his GP because you're a great intern, and you found out that his sodium has been less than 130 for three years. Speaker 1 Hmm, no one did Speaker 2 anything. Nowadays anything Speaker 1 yet yet? Here we go. So we do the same things with done before. So we send off the PED, serum your announcement. Aldi and sodium and just on that one actually. I know we didn't talk about it before but even if they're like an hour or two different it's you still might get some useful information out of it so try and get Speaker 2 them sent off. At the same time to is, is fine. I struggle getting it on the same Speaker 1 day. Yeah, probably should be the same day but send it off when you can and depending on how kind of equivocal in the mid-range. The result is or how extremely result is you still might get some useful information about how your kidneys are going concentrating, your urine. Speaker 2 Yeah. Then you want to take a history. So he's past medical history. He's got AF osteoarthritis COPD. You've checked his Med chart, there's nothing whirring then or thiazide. No psychotropics. His fluid in his diet, is all pretty normal and his euvolemic on a fluid review. There's really not that much to find you. Finally get back, you're paired, urine and serum. He's got a serum sodium of 125 and the urine sodium of 48. So that's high that sends inappropriate his plasma osmolality osmolality Leti is 250 and his urine is more concentrated than that at 280. She also sounds quite inappropriate. Speaker 1 So yeah. Sounds very Speaker 2 inappropriate. So this is sounding like a syndrome of inappropriate ADH or something called a reset ozma stat, which we probably won't go into, but if you're a BPT you should go and look it up but but these are a diagnosis of exclusion. So we're going to look through and make sure it's not a couple of other things first. So this is where you get out the blood flips and you want to check to make sure that Don't have quotas all deficiencies so you were doing morning cortisol and ACTH stimulation test and you'll send off some thyroid function tests. And if all of those things are normal, then you can call this the syndrome of inappropriate ADH. Speaker 1 Yeah, so syndrome of producing too much a th and he diuretic hormone. So that's a in syndrome of inappropriate a. Th because your secreting way too much antidiuretic hormone you're retaining all This extra fluid. So you get a low serum osmolality and sodium, but in your urine it's actually quite high. So instead of getting rid of the all this extra fluid through urine, your body's actually concentrating your urine. So you'll have a higher urine osmolality and higher urinary sodium. Speaker 2 Yeah, and the causes are many and varied. Lots of the causes are respected trees or even pneumonia asthma. Atelectasis can do it as well as the more severe things like acute, respiratory. ettore failure malignancies like small cell, lung cancer, which can actually produce ectopic a th but also other kinds of malignancies the few problems in the brain box with Strokes infections and Trauma, then just in general surgery, some medications, it can be hereditary even nausea can cause cause sath and everyone's favorite cause idiopathic All right, so what do we do? How do we treat it? Speaker 1 What's first line? So, first line you want to fluid restricts? Because I've got way too much water on board. Speaker 2 Yeah, so on the Australian therapeutic guidelines. They suggest 500 Mills to one liter and what you decide on. Will depend on lots of things. It's often a bit of often a bit of trial and error and you just need to monitor very closely. And I always find that the patient's humanness gets in the way of things if you try to be to algorithmic, if you do want to be very specific, Talk about it. You can have a look at the European guidelines that have a sophisticated calculation. But generally What's Done in the wards is a bit of a guess at what's going to work. Speaker 1 And you can always start off with a more conservative fluid restriction and then increase it in a couple of days. Hmm, increasingly meaning, like restricted, Speaker 2 increase it as in decreases. Yeah. And I also mentioned earlier the vasopressin receptor antagonist, which are indicated in sath, but we don't really use them yet in Australia. Okay, so management in general, not just for sah, but summary of management for hyponatremia. Firstly, if there's a causative drug, stop it. If you think they're dry, give normal saline. If you're not sure, but they're definitely not overloaded. Then you can trials, low, sodium chloride. And if you That euvolemic fluid restriction is a pretty good place to start. If you want to try something else, make an Endocrinology referral first but the options would be hypertonic saline. 12, Upton, and probably check moving to more closely monitor the environment. Like the Intensive Care Speaker 1 Unit. Yeah. If they're seizing, that should probably be nice to see you. Probably. Yeah, problems. So almost finished is scintillating lecture on lighting. The lighting is that even he say it, I'm not even sure. Since insulating scintillating Shinto. Scintillating probably scintillating. All right let's give you Speaker 2 a moving on the take home point. So the first one, we've said it a million times but send the urine and Serum osmolality is early before the patient is given any IV Therapy, Speaker 1 the most common medications, which calls it a particularly thiazide diuretics more than the other ones. But also in Dapper, my dance like a Tropics, Speaker 2 choose an algorithm flow chart that you like and stick to it. So Life in the Fast Lane one other one on up-to-date. Speaker 1 Don't overcorrect, if it's chronic corrects really slowly and remember that you can cause more harm than good if you trigger the Central pontine and sorry, the new name osmotic, demyelination syndrome. That's right. Speaker 2 Yeah. So in general, do less and measure it more. And lastly, salt and water can be dangerous. And especially, especially advice, is a good idea here, because when you go wrong, you can go very wrong. Speaker 1 So hopefully you followed us along, therefore, through the depths of our discussion of electrolyte derangements. And Now, you like, BEC have been through that marathon and ready to run your own Marathon Physical sense, and you've learnt about the words insulating, or at least learned that you need to look it up like me, which I will do soon. But even if you didn't like this podcast, if you liked any of our other podcasts like us on Facebook or recommend it to a friend, maybe yeah, recommend them. Specifically, maybe not this one. Nah, I think other your words Speaker 2 graduations to this. Three or four of you. And thank you so much for all the support. We love the messages that people send through. And hopefully this sound quality is a bit better than the last one. So sorry about that. And thank you for posting on the Facebook page, liking the likes and we will see you next time. Catch you soon. Bye.