nm0370: you're not going to get any I-T aids for this talk you're not going to get any slides you can take notes if you want to er i've prepared some handouts for you with everything i'm going to say on here so feel free not to take any notes it's all on there [laughter] the reason i teach this way is t-, to get your attention and er to hopefully prevent you from falling asleep for this talk so the subject of today's talk is kidney stones but first of all i'd like you to tell me what this is i'm i can assure you i'm not a very good ss: train nm0370: it's a train okay and [laughter] er so you're all trainspotters er i can tell because you know what a train looks like er and the theme of this morning's talk is to try to persuade those of you who are not trainspotters to become trainspotters actually it's very interesting the whole subject of trains and why do you think that kidney stone disease has got anything to do with trains and trainspotters anybody think laterally speak up sm0371: movement of urine the flow of u-, nm0370: no no it's a trick question sm0372: we need trains to spot them nm0370: sorry sm0372: we need trains to spot them nm0370: very good very good i didn't think of that one er [laughter] i i think that the reason why it's similar to trainspotting is that most people think trainspotting is rather dull and er most people also think kidney stone disease is rather dull n-, but i happen to find it very interesting and i'm trying to get convince you this morning that it is interesting and trains are interesting er why do you think that trainspotting is dull ss: nm0370: speak up sm0373: it's monotonous nm0370: it's monotonous isn't it it's very common there are a lot of trains about and it seems quite easy doesn't it trainspotting but you try sitting there on Crewe station all day long writing those little numbers down and er in fact it's a lot harder than most people think trainspotting and and it's perhaps more interesting than many people think and i'm going to try to convince you that kidney stones er are harder than you think and perhaps more interesting than you think why why are k-, why is kidney stone disease important tell me something about the epidemiology of kidney stone disease sf0374: er nm0370: if you've got no idea say so sf0374: 'cause it causes an obstruction sf0375: no idea nm0370: okay so it's a cause of obstruction yes anybody else sm0376: painful it's painful nm0370: painful and in fact and that's the key and that's one of the similarities with trainspotting er [laughter] it's painful and it doesn't really matter and why doesn't it really matter why does kidney stone disease not really matter it doesn't kill you so people don't care about diseases that don't kill you and they care about diseases that do kill you and kidney stone disease is a classic disease which is very important very common but doesn't kill you which is perhaps why nobody's interested in fact there isn't a single group of kidney doctors in the U-K looking into kidney stone disease at the moment so if one of you wants to become famous do a PhD on the pathophysiology of stone disease so it doesn't kill you h-, how common is it anybody sf0377: very nm0370: very do you want to put some numbers on that sf0377: no [laughter] nm0370: anybody want to put some numbers on that sf0378: ten per cent sf0379: twenty-five nm0370: it's yeah nearly actually twelve per cent of men five per cent of women have a stone at some stage in their lives and kidney stones are a bit like trains they just keep coming they keep recurring er and in fact fifty per cent of people of of that vast number of people so many people in this room will have had a kidney stone at some point in their lives er or are about to perhaps today and [laughter] er and fifty per cent of those people have another attack in the next five years so it's suddenly becoming a bit more interesting it and what's interesting about it is it's one of the commonest chronic diseases but it's one of the diseases we know least about and it's one of the diseases that seems simple but perhaps isn't so perhaps this X-ray is really a primary example of why you think it might be simple what what does that X-ray show gentleman in the front here [laughter] sm0380: two kidney stones nm0370: yeah very good two so you don't need to be a doctor you don't need to be a medical student to diagnose that you see the spine you see the hips and you see a couple of kidney stones and what why do you think they're kidney sto-, what makes you say they're kidney stones sm0380: they're calcified nm0370: okay so they're calcified in fact most kidney stones are calcified how many kidney stones are calcified guess calculate a guess if you don't know sm0381: eighty per cent nm0370: eighty per cent eighty per cent are calcified and therefore you can see on a plain X-ray but twenty per cent aren't there are twenty per cent of trains you can't see so it's suddenly becoming a more interesting disease so tell me about the stones you can't see these two ladies what are they made of stones you can't see on a plain X-ray sf0382: urate nm0370: urate yeah what percentage of stones are urate stones sf0382: two per cent nm0370: about seven per cent okay and there are a lot of causes of stone disease and in the first stage of this talk i'm going to talk about the aetiology of stone disease c-, causes of stone disease and then we'll go on to the treatment what we're going to do about it so first of all tell me somebody the most likely composition of that stone i'll give you a clue calcium sf0383: phosphate sm0384: phos-, nm0370: sorry sm0384: phosphate nm0370: no sm0385: oxalate nm0370: oxalate okay so about seventy-five per cent of the calcium containing stones which are eighty per cent of all stones contain calcium oxalate and in fact the pathogenesis of these stones is ill understood one of the oldest operations in the history of mankind is what what did the Egyptians do to people with stone disease schistosomiasis the Nile papyrus rolls tell me about the Egyptians you're not a group of medical historians here [laughter] but one of the earliest operations recognized by mankind is cutting for stone and Egyptians used to cut for stone by putting a cut through there so bit of wine bit of beer and they used to cut into the patient's abdomen to remove stones but this is one of the oldest diseases in the history of mankind and one of the oldest operations in the history of mankind okay so would anybody like to be brave and tell me er about the pathogenesis of kidney stone disease in other words the common causes of the common stones we've been talked about who's going to be brave and tell me about some risk factors sm0386: infection nm0370: infection yes sm0387: dehydration nm0370: dehydration yes more common in hot countries sf0388: is it more common in men nm0370: more common in men nobody knows why but almost all kidney disease is more common in men i personally think it's because we don't get pregnant and women er get all this lovely twenty-four-thousand mile service when they're pregnant and all these diseases are found out and us men are left to rot [laughter] in our forties and fifties and then we get stone disease and heart attack and we leave our young wives er okay [laughter] so who's going to help out the people at the back tell me a bit more science tell me about some of the things that are in the wee wee or not in the wee wee that predispose to stone disease sm0389: diabetes nm0370: diabetes no well yes and no yes via papillary necrosis yes but yes and no let's see how much reading you've been doing sm0390: urate crystals nm0370: okay so there are certain abnormalities in the urine that predispose to stone disease and what the urine is is a solution of salts and most of those salts are at a near supersaturation level so in other words you don't have to do much to the urine for the salts to come out of solution and some of the salts are as follows urate at the back anybody else like to offer any others sm0391: cysteine nm0370: cysteine that's y-, yes that's more of a specific you're right but more of a specific cause of stone urate calcium oxalate if you have high levels of those in your urine that predisposes you to stone disease and low levels of cysteine again how these factors interact we don't really understand but there's a fair amount of evidence that people with any of those abnormalities are more likely to get stones than other people it doesn't say it's a cause it's a risk factor tell me about some more specific causes gentleman at the front cysteine anybody else give me some rare stuff infection what type of stones do they produce it's going to be a long morning isn't it [laughter] you weren't expecting questions fired at you were you you just lecture don't want to be embarrassed at the front struvite stones so-called infection stones interestingly more common in women why do you think that is so ss: nm0370: speak up it's 'cause women are more likely to get U-T-Is it's as simple as that so some stones most stones are more common in men but a few stones are more common in women okay there are some rarer causes of stones that i don't intend to go through today in great detail there's something called a xanthine stone a dihydroxyxanthine stone and a load of others you can look it up if you want to there are some very rare cause of stones but we're going to mainly talk about the common causes of stone okay er if you were going to choose one of those urinary abnormalities as a problem which you can sort out in a patient with recurrent stones what would it be what do you think's the most common of the things that i've described so far sm0392: low urine volume nm0370: low urine volume yes and no lots of little old ladies drink four- hundred mls a day and don't die and don't get stones probably the calcium of of the risk factors for renal stone disease hypercalcuria is probably the most important in fact sixty per cent of people who have classical calcium oxalate stones have so-called idiopathic hypercalcuria so many of you in this room will have it has anybody would anybody like to volunteer any normal ranges of urinary calcium excretion this is a hard one isn't it tell me the normal calcium there you go that's an easier question gentleman at the front you're going to get poor chap's [laughter] going to get picked on chap behind him normal calcium level sm0393: two-point-five in plasma nm0370: okay not bad okay two-point-two to two-point-six so you should know the l-, the normal levels of all basic bioclinical parameters by now and if you don't i'd like you to learn them because you're going to need them by the time you hit the wards er and you don't need to know the normal twenty-four hour urine excretion i'm er i have to look it up and er one to four millimole per twenty-four hours of urine and there's an arbitrary line of over seven-point- five for men and six-f point-two-five for women but interestingly er eight per cent of normal people er who don't have stones have so-called pathological hypercalcuria what what does that tell you if eight per cent of normal people have high levels of calcium in their urine sm0394: there's something else there nm0370: yeah there are other factors involved and clearly this is only one factor but it also tells you how we get normal ranges how do you think just as a slight aside how do you think there's a clue how do we get normal ranges how do we develop these numbers of normal ranges two-point-two to two-point-six where do they come from sm0395: a statistical average nm0370: statistical average but where do we get the data sm0395: patient data nm0370: patient data where do we get that from sm0395: hospitals nm0370: hospitals which hospital where when sm0437: renal wards sf0396: renal wards nm0370: renal wards no not particularly i mean a lot of our normal ranges are taken from old studies of vast numbers of er white American males entering the army fifty years ago and ma-, many of our normal ranges are completely wrong er but even if they are right we still have to develop a normal range and what we do is we screen a vast number of the population several thousands and we say the normal range is within two standard deviations of the mean and what's wrong with that as a method of describing a normal range sm0397: there's another five per cent of the population outside of that nm0370: very good okay so there's five per cent of normal people se-, people who are seven foot tall aren't necessarily ill neither are people who are four foot tall and it may be that people either end of the normal range er the normal range are perfectly normal so whenever you hear about a normal range and people hit you with statistics like i've done this morning you've got to think about how we develop those normal ranges what do they mean so the fact that as i told you eight per cent of people who don't have stones have hypercalcuria means nothing means absolutely nothing it may be these are just normal people tail end Charlie four foot people or seven foot people so you should analyse er at the end of this talk i'm going to give you a list of fifty facts and i want you to analyse these facts with er some degree of caution okay er tell me a little bit now about some more specific causes of kidney stones right so we've had cysteine at the front er wh-, we've had infection and a variety of other things at the back what anatomical problem might predispose you to stones sm0398: stric-, sm0399: stricture nm0370: strictures okay pelvic utero junction obstruction yeah anything else i'll give you a clue this is a kidney kidney-shaped thing just for my own interest how big is a kidney roughly these two ladies how big is a kidney it's about the size of your fist okay it's twelve by six by three er with a minimum er height vertical distance of ten centimetres about a hundred-and-fifty grams one of the smallest organs in the body it takes a fifth of the cardiac output so it's very important it's very small and i like it er [laughter] so now i've given you a few clues so what other anatomical problems might predispose to stones we've said strictures okay well what do you think these bits of the kidney are called er you've done lots of anatomy what are they called sf0400: calyces nm0370: calyces okay can the calyces fall off yeah what process leads to the calyces falling off sm0401: nm0370: sorry oh dear okay anybody what process do you think could lead to the calyces falling off i mentioned it already okay papillary necrosis so there's which has er a variety of causes between diabetes sickle cell disease and lots of other causes and these can fall off block the drainage system stones can form behind it cancers any obstruction to the urinary tract anywhere where there's stasis it can lead to worsening in the supersaturation of the urine so as well as having the biochemical risk factors that we've talked about so far there are also anatomical risk factors to kidney stone disease okay er cystinuria just slight aside gentleman mentioned it er at the front there er coming back to cystinuria if you don't know anything say you don't know it's all right not to know does anybody want to help him out why is it important no anybody tell me a sentence about cystinuria sm0401: it's hereditary nm0370: hereditary very good okay and that's why it's important and a few causes of stones are hereditary and therefore if you find a patient with cystinuria you might do what sm0402: do an intensive history nm0370: yeah look at the rest of the family you know look at the parents look at their children warn them that they're going to develop kidney stones they don't kill you but they're bloody irritating they're very common cystinuria some studies up to three per cent of stones are undiagnosed cysteine stones and so this is important inherited cause of kidney stones and there is very effective treatment for it okay er now then let's talk about how kidney stones present let's er pick on somebody else now this gentleman here how do you think kidney stones present sm0403: pain nm0370: pain sm0403: you can have pain in even nm0370: okay very good so pain pain is the hallmark of kidney stone disease okay tell me about the pain of kidney stone disease sm0404: er acute sharp pain nm0370: yes sm0404: in the flanks nm0370: very good anything else about it you're right sm0404: er i don't know nm0370: anybody want to help him out sm0405: it moves nm0370: it moves particularly it radiates through the sm0405: spine to groin nm0370: yeah loin to the groin to the testicles in a man sm0404: is it spasmotic as well nm0370: yeah tell me more about the spasmodic nature of renal colic what you're getting at sf0406: er nm0370: what is a colic sm0407: contraction sm0405: the contraction's quite like an obstruction nm0370: very good okay so the three main forms of colic are gallbladder colic kidney colic interstinal colic when do you get interstinal colic when you want to go for a poo [laughter] you have faeces obstructing your bowel the bowel above the faeces contracts down on it and it causes pain and that's when you get colic you know it yourself you're sitting there you're dying to get out of this lecture you really want to have a poo it's a [laughter] big poo you've been building up to it you had a curry last night this is an important poo [laughter] and you feel pain in the tummy and that's colic that's interstinal colic and renal colic is exactly the same type of pain but much much worse and it's said to be one of the worst of all pains but there is a group of people that know it's one of the worst of all pains who traditionally likes to mimic renal colic and why sm0405: drug addicts nm0370: drug addicts okay it's very common for drug addicts to present to A and E er with renal colic and er there's probably a couple er in this lecture at the moment er trying to er get some hints how to pretend to have renal colic er and when you're housemen and S-H-Os it's important to look for people who are pretending to have renal colic 'cause what they want you to do is give them some pethidine or some morphine or diamorphine and er it's one of the classic catches er so renal colic is like all colics it's a spasmodic pain in other words you have no pain you have terrible pain you have no pain you have terrible pain and classically when there is no pain there is zero pain so you go from complete absence of pain to severe pain and a patient with renal colic usually writhe around while they're having an attack and then when they're not having an attack they're absolutely fine so there is a classical picture of people with renal colic but unfortunately it's not that easy er pain is not the only way in which kidney stone disease presents wh-, why do you think pain is not the only way in which kidney stone disease presents sm0408: you're obstructing urine output nm0370: yeah in other words the stones may have appeared finish my sentence [laughter] it's like Blankety Blank this the stones may have appeared adverb two syllables [laughter] sm0409: in the er [laughter] nm0370: slowly so if things happen slowly in the human body classically the pain acquired related to that particular problem er is non-existent in other words there is no pain er and this is true of many systems of the body if something grows slowly the body becomes accustomed to it and so it is possible to have severe kidney stone disease without causing obstruction nephropathy which can lead to dialysis transplants and everything horrible meeting Dr namex er and therefore we have to be diligent about looking for stone disease in people who don't have pain the pain is not the only presentation pain is the classical presentation what are er some other atypical presentations of stone disease sm0410: haematuria nm0370: yeah haematuria very good macroscopic haematuria er again it's pretty unusual pain is much more common anything else sm0411: unconsciousness nm0370: yeah yeah no true you know it possible if you er if you ruptured one kidney completely went into acute renal failure eventually you'd become unconscious and i've seen that happen well infection caused by the stasis behind the stone can be a presentation of kidney stone disease and they say that a single urinary tract infection in a man should always be investigated women don't matter too much you're always having U-T-Is [laughter] soon as you become sexually active you start having U-T-Is perfectly normal that's er the name of the game can't do anything about it have one a year it'll go away if you don't have antibiotics it'll go away if you do have antibiotics it's not serious and it's not going to cause kidney stone disease but sometimes if a woman changes her pattern of U-T-Is from one a year or whatever er then it may be a sign that she's developing a stone and if a man ever gets an infection they should always be investigated for stone okay so there are differences in the way we investigate men and women er who do you think these er patients present to lady with the brown jumper there who sf0412: G-P nm0370: G-P yeah quite often they'll go to their G-P first and if they're not too bad if they're bad where do they go ss: A and E nm0370: yeah they'll probably go up to A and E and this is a problem 'cause they're are coming up and the pain is pretty bad so if you genuinely have it you also tend to go fairly rapidly to A and E and they go through a nice system you see a triage nurse Tony Blair ticks his boxes [laughter] the patient is seen between four hours you know all about that game don't you there'll be there'll be triage nurses and as soon as you see them we tick the box and then we falsify all the data to make us oh oh sh-, i'm on camera [laughter] er the er to make sure that our hospital gets enough stars anyway er that's another story so the patient comes up to A and E they're seen by a triage nurse oh dear this might be renal colic and who who are they pushed towards sm0413: X-ray nm0370: X-ray so they have an X-ray then what happens who who who who are they then next seen by ss: surgeon nm0370: a surgeon and this is a disaster [laughter] when they see a surgeon why is it a disaster they see a surgeon sf0439: nm0370: 'cause they're completely non-thinking people who couldn't be physicians [laughter] is that what you said sf0414: yeah nm0370: [laughter] okay okay sorry i don't i don't don't let me put words in your mouth though [laughter] er oh that's on camera as well [laughter] er no surgeons are good because they know how to get rid of the pain and they can spot white things and they can spot it when they don't come out and then they know what they have to do next why are surgeons bad for kidney stone disease bearing in mind the epidemiology which we've talked about sf0415: they only treat the problem nm0370: sorry they don't look for the cause and in many patients there is an identifiable cause but there's one famous American study where ninety-seven per cent of people in this study were found to have some form of biochemical abnormality which some people wouldn't consider a cause and are ninety-seven per cent of stone form is investigated course they're not who who do you think that the thinking surgeon tends to investigate let's have some er comments from the back so two ladies with the scarves there who's the thinking are you going to be a thinking surgeon don't know yet [laughter] okay who do you think the thinking surgeon investigates hundred-thousand people having stones every day can't investigate them all who do you think they who would they focus on lady with the pink scarf sf0415: no idea nm0370: no idea lady next to her sf0416: anyone with a family history nm0370: yeah good so if they've got a family history they'll spot that if they're asked the question but if they don't oh yeah my mum had stone my grandmother we've all got stones but don't know why and er so they don't particularly er investigate the people who should be investigated er what most surgeons do is that they can count they can count up to two [laughter] and that's very important for kidney stone disease because on the second stone which is the number after one [laughter] they know to investigate it and that's what most surgical practice is they investigate people after the second episode of stone unless the stones are particularly horrendous like those ones or they have a staghorn calculus or something like that what's a staghorn calculus okay it looks like a staghorn but lady there what do you think causes staghorn calculi sf0417: i don't know nm0370: anybody sm0418: is that just still in the kidney sm0419: nm0370: sorry sm0420: is it still in the kidney nm0370: still in the kidney it's called staghorn because it looks like a staghorn because it fills up the whole of the pelvic-caliceal system and some people would say that what i'm a-, what i'm trying to draw here is vaguely like the staghorn what predisposes to staghorn calculi which interestingly often don't present as pain infection infection stones er so these are particularly common in women and a surgeon will know to investigate something like that because it's bad and it's big and it looks like a staghorn and now okay i've stood here as a physician slagging off my surgical colleagues who i work with on a daily basis and er why do you think it's actually a good idea that they don't investigate everybody with a single stone gentleman here why is it a good idea not to investigate we talked a bit about the epidemiology at the start sm0421: because it's so common nm0370: it's so common and we can't possibly be investigating five-million people because it's too expensive and you could argue that er it doesn't really matter anyway 'cause they don't kill you and most people have one episode maybe two in their lives it doesn't cause kidney failure it doesn't cause obstruction it doesn't cause any major problem so it may be yet another way in which the N- H-S cuts corners by only investigating people with two or more stones okay who do who do you think in most er er centres centres of excellence like Coventry actually sets up kidney stone disease clinics it's a trick question sm0422: nobody nm0370: nobody absolutely nobody there is no specialist kidney stone disease clinic in Coventry in fact many of the the big cities in the U-K unless a doctor has a particular interest in kidney stones one of our surgeons does have some interest in kidney stones but it's not his primary interest and none of the six nephrologists here have a particular interest in kidney stones so one of the commonest diseases of all time is not looked at by anybody in particular just by a mishmash of people and therefore mistakes are made there is nobody to refer to and in fact in the U-K there are almost centres with an interest in kidney stone disease there was one at U-C-L in London i don't know if it's still going er so there you go do your PhD the pathophysiology of stone disease become famous go on world tours set up a clinic in namex [laughter] and you might do some good okay so we've talked a bit about their presentation what about their investigation okay let's pick on somebody else gentleman with the Nike black top tell me how you'd like to investigate somebody who presents with a kidney stone simplest test first remember bit of a touchy-feely namex students we do nice simple things first [laughter] we don't go for M-R-Is sm0423: X-ray nm0370: X-ray wrong okay it's simpler than that anybody else sm0424: U-neg nm0370: wrong simpler than that sm0425: palpate nm0370: sorry sm0425: palpate nm0370: palpate well we've moved you're right we would do that but we've moved on from simple very simplest the most simple test of wee wee sf0426: give us some clue nm0370: giving you a clue sf0427: a dipstick sm0428: speaking of what are we testing for [laughter] nm0370: a urinary dipstick okay possibly the simplest test of urine and possibly one of the most important er it can tell you lots of things lots of things like whether there's protein in the urine blood in the urine which would be consistent with stones or is it what is the blood on a urinary dipstick caused by the blood in inverted commas sf0429: er lysis of red blood cells nm0370: very good so if you forget everything i say this morning just remember this that the blood on a urinary dipstick is not due to blood cells it's due to haemoglobin in other words the lysis of blood cells and why is that so important and why do so many surgeons therefore put people into acute renal failure you've got to think laterally now lady with the blue headband there so why is that so important that the urinary dipstick does not measure blood cells it measures a component of blood why does that lead to so many clinical errors which you're not going to make 'cause you're never going to forget this 'cause i've picked on you right anybody help her out sm0430: all the remaining debris from the cell is stuck in the kidney nm0370: yeah and there are many other causes of haemoglobinuria other than diseases where there is haematuria so there are many causes of haemoglobinuria myoglobinuria [sneeze] et cetera all of which will give you a false positive blood inverted commas on the urinary dipstick so it is it is a good test and it's a bad test and the reason it needs surgeons to call if you've an acute renal failure is somebody presents with a stone what do they do history examination blah blah blah lots of blood tests yah-dah-dah X-ray I-V-Ps their standard first line investigation which contains nephrotoxic dye and therefore somebody who's dyed about every rhabdomyolysis because some other cause is having an unnecessary investigation which will make them worse and i have in my time saved a few people from acute renal failure by stopping surgeons do I-V-Ps nf0432: five minutes nm0370: okay so if you forget everything else i say today just remember that that the blood on a urinary dipstick is not made positive by blood cells it may be okay so other tests beloved of kidney doctors other than a urine analysis let's stick with the lady in the blue headband the other simple test of the urine other than putting a dipstick in what would twenty years ago if you were my houseman i was your consultant what would i be expecting you to do for my ss: taste it nm0370: taste the urine possibly [laughter] sm0433: sieve it nm0370: sorry sm0433: sieve it nm0370: sieve it and microscope it because many causes of kidney stone disease can be diagnosed on microscopy unfortunately it's a skill that most of us have now lost or forgotten and maybe i'm harking back to the good old days [laughter] when things were better when we had leprosy and T-V and [laughter] social deprivation but it was quite good fun to be able to make diagnoses by microscoping the urine which we no longer do and some disease particularly s-, cysteine disease where there's a classic type of benzene ring crystals can be diagnosed from simple microscopy of the urine you don't need any fancy tests so yes we go to do blood tests yes we go to do X-rays but we do simple tests first an M-S-U probably basic blood tests including a serum what ss: calcium nm0370: calcium why sm0434: nm0370: yeah well it's one of the commoner rare causes so but most people with hypercalcuria are not hypercalcaemic so everybody does the count and it's almost always normal and i think this is one of the reasons why surgeons get fed up with investigating people with stone disease 'cause everything's always normal but if they look for the things which were there they would find them to be abnormal in a lot of people so we do those simple tests er we do it twenty- four hour urine looking for calcium urate oxalate citrate all the other things but you have to know how to interpret them and that's where it becomes a lot harder and again this may be one of the reasons why most of these patients are not investigated so plain X-rays are probably the single most useful test in eighty per cent of people with greater instance of stones which is why i brought that one up today but most surgeons would do an I-V-P as well as a plain X-ray why would they want to do an I-V-P give horrible nephrotoxic dye with significant mortality sm0435: want to check behind the stone nm0370: yeah to see if there's any obstruction behind the stone er to see if they they need to do anything quickly what size stones pass naturally calculated guess if you don't know sm0436: couple of millimetres nm0370: sorry sm0436: couple of millimetres nm0370: yeah less than four and we would watch a patient with a stone of less than four millimetres four above usually requires some form of intervention how can we intervene how can we extract stones lady with the brown top on again sf0412: er blocked by the er nm0370: ex-, speak up sorry shush everybody listen sf0412: [laugh] er i don't know nm0370: this again we sometimes shout at the stones we can use sound waves to shout at the stone sometimes we can go up there pull them out and various er horrible instruments er usually done under G-A though not always er we can use a Foley basket we can shatter them we can get them out there are various ways of doing that the last resort is an open operation doing what the Egyptians did it does work er but er it does leave quite a big scar okay so they're the investigations we tend to do on patients with recurrent kidney stone disease and perhaps we should investigate them all er finally er i'd like to now convince you that this disease which you all thought was boring er unimportant and like trainspotting is not such a boring trainspotting disease first of all 'cause about ten per cent of you roughly are going to have one of these in your lifetime it's going to hurt it's going to stop you from going to work and is likely to happen again and if we did make some effort to get interested in a disease which is about as interesting as trainspotting we might be able to stop some of these attacks from happening okay thank you very much