62-year-old (Female) with End-Stage Renal Disease

00:01 Okay, guys, we have a really challenging question here. Let’s buckle down in focus.

00:06 A 62-year-old female with end-stage renal disease secondary to diabetic nephropathy on hemodialysis presents complaining of fever, worsening fatigue, and muscle weakness for the previous 48 hours.

00:26 The patient describes her muscle weakness as symmetric and worse in the upper limbs.

00:31 The past medical history is significant for long standing diabetes type 2, complicated by end-stage renal disease that is well managed on hemodialysis for the last six months.

00:45 Current medications are lisinopril, verapamil, and metformin.

00:50 On physical examination, the temperature is 38.6 °C, the pulse is 80, blood pressure is 95/60, respiration are 24, and the patient is Sat-ing 95% on room air.

01:07 Cardiac and pulmonary exams are unremarkable. The abdomen is soft and nontender.

01:14 The strength is 3/5 in the upper extremities and 4/5 in the lower extremities bilaterally.

01:21 Sensation is intact.

01:23 Deep tendon reflexes are absent in both the upper and lower extremities.

01:29 The 12-lead EKG shows the following as seen in the picture.

01:33 The patient is started on continuous cardiac monitoring.

01:37 What is the next best step in the management of this patient? Answer choice A: Administration of IV calcium gluconate; Answer choice B: Order a stat serum potassium level; Answer choice C: Emergency dialysis; Answer choice D: Administer regular insulin 10 units and 50 ml of dextrose 50% in water; or Answer choice E: Administer IV sodium bicarbonate.

02:14 Now take a moment to come to the answer by yourself before we go through it together.

02:23 Okay, as I warned in the beginning, this is a challenging question but outrageously important because it teaches a few really important principles and the one that I really want you to take home here is answer the question being asked not the one that you wanna answer.

02:41 Now if you look at the question stem they say, what is the next best step in the management of this patient? That means of course whenever they write that, more than one of the answer choices can be correct but you need to pick the absolute best one that’s appropriate for the clinical situation being describe and you’ll see why that is so important as we go through the answers right now.

03:07 So let’s go to the questions characteristics.

03:10 Now this is an internal medicine question and the patient really has a lot of renal complications with renal pathology, so this is a Renal question.

03:18 Now this is also a two-step question.

03:21 First thing we have to do is figure out what is going on with this patient and then second step, what is the next best step for this patient in management? And of course, here at the stem is absolutely required because we have to read and pull out various parts of the question stem and figure out what is going to lead us to the proper diagnosis and then from that, figure out what is the best next step in management.

03:47 Now, let’s first determine the diagnosis together.

03:51 Now here we have a female patient with end-stage renal disease that we’re told to secondary to diabetes.

04:00 Now, the patient has been on hemodialysis for the last six months.

04:05 Now, end-stage renal disease is the irreversible stage of kidney failure that the treatment is either hemodialysis or kidney transplant.

04:16 Now, the presenting symptoms for this patient are fever, worsening fatigue and muscle weakness.

04:25 Now looking at these symptoms themselves really gives you a pretty wide differential diagnosis.

04:32 The patient has fever; well that could be a viral infection, a bacterial infection, etc.

04:38 The patient has fatigue -- well, that could be hypothyroidism, it could be a treatment side effect, it could be iron deficiency, it could be depression, it could be cancer -- you get the point, etc.

04:51 The patient now has muscle weakness, well that could be a neuromuscular disorder, it could be an electrolyte disorder, etc., thus the chief complaints and symptoms really don’t help much, they just throw you for a loop so you gotta then look at the patient’s underlying condition to help you, and that’s what really happens in this USMLE questions.

05:12 The patient’s symptom is most likely linked to the underlying condition.

05:18 Now, for this patient, end-stage renal disease being the underlying condition, which is a dysfunction in the patient’s ability to filter their own blood in their kidneys and actually manage electrolytes, so hemodialysis has to do it for them.

05:35 Now, if we look at the EKG here, we are able to see peaked T-waves and we also see a wide QRS complex.

05:46 Now, these you just have to know are highly suggestive of hyperkalemia.

05:53 Now, hyperkalemia is an absolutely well-known complication of end-stage renal disease and boy oh boy, you better know that too! So what’s interesting is that the patient’s symptoms are actually consistent with the hyperkalemia because the patient is endorsing muscle weakness and fatigue that is commonly seen in patients who have hyperkalemia thus the diagnosis here is severe hyperkalemia? Now, the next step here after we figure out the diagnosis is to figure out the next best step in management and let me highlight that again, the best step in management.

06:36 Now, severe hyperkalemia puts you at a significant risk for cardiac arrhythmias, now, this is due to cardiac over excitability due to lower depolarization thresholds in the cardiac myocytes.

06:55 This is absolutely a medical emergency and once you have that in your head you will be able to understand why USMLE loves asking what is the next best step in the answer because they want you to figure out the acuity and next best step because that’s what you’re going to be doing as an intern, resident, and of course, attending.

07:18 Given that severe hyperkalemia is a medical emergency, the management has to be aimed at rapid management and also in this case the rapid reversible of cardiac overexcitability, so what you don’t want to do is pick an answer choice that gives you delayed management, you want to pick an answer choice that gives you immediate right now management and also protects the heart because the highest potassium really is dangerous towards the heart.

07:49 So the first line treatment for severe hyperkalemia is protecting the heart and the intervention there is giving IV calcium gluconate to stabilize the threshold potentials of the cardiac myocytes and that’s answer choice A, administering IV calcium gluconate.

08:12 Now, let’s talk about that first and then we’ll go through why all the other answer choices are wrong.

08:17 Now, giving IV calcium gluconate is absolutely critical to stabilize the myocardial membrane and prevent a potentially lethal cardiac arrhythmia.

08:30 Now, when patients are on hemodialysis they can develop some type of systemic illness or infection and have a fever, just like what this patient had and then they can actually present, as a result of that systemic assault, with hyperkalemia and this actually happens quite commonly but most of this elevation in potassium are usually asymptomatic and mild, but at higher levels of potassium, the hyperkalemia usually manifest as muscle weakness, fatigue and the absence of deep tendon reflexes.

09:09 Now, in the setting of hyperkalemia you’re going to find peaked T-waves and a widen QRS complex that is absolutely suggestive of severe hyperkalemia and you have to memorize those EKG findings and once you identify severe hyperkalemia, you need to aggressively treat and prevent the first scary problem which is a potentially fatal arrhythmia by giving IV calcium gluconate.

09:39 Now, that’s the first step.

09:41 You don’t want to wait on ordering a potassium level, you don’t want to do any other diagnostic testing, the EKG gives you enough of the actual answer of hyperkalemia, the clinical situation makes sense, treat the patient as the next step in management and that’s why this is a tough question.

09:59 Most medical students are used to working up more of the problem and then intervening, but in this case, you have to take whatever clinical situation is in front of you, the patient’s tender complaints and exam, and the EKC findings and that alone is enough to stop and treat while you’re doing the further workout -- you don’t just sit there and wait.

10:20 Now let’s go through the other answer choices to reinforce that point.

10:24 Now, answer choice B is ordering a stat serum potassium level.

10:28 Now doing so, okay, imagine that the patient’s sitting there, the nurse pulls some blood and throw it into the lab, what are you gonna do? Just sit there while the patient is severely hyperkalemic hoping they don’t have a cardiac arrhythmia -- no! You gotta intervene, give IV calcium gluconate so thus you can’t sit here and just wait for a level. The clinical situation is enough for you to know to treat.

10:50 Well, look at options choice C, emergency dialysis.

10:54 That may have been appealing to you because you’re just like, wow, I can just fix the problem.

10:57 Well, let’s get realistic.

11:00 Ordering hemodialysis takes time, the hemodialysis tech has to get the machine, bring them down, hook it up, get a renal consult, have the nephrologist order the natural hemodialysis, that’s not going to happen very fast and that’s going to take up time and again you’re just going to let the patient sit there while you do all that? No, you gotta intervene, give IV calcium gluconate.

11:23 Now, answer choice D of giving insulin and D5W is actually part of the elevated sodium treatment protocol but before you do that, what you need to do is give IV calcium gluconate to stabilize the heart because giving the insulin causes potassium to go into the cells and giving sugar is to prevent hypoglycaemia but IV calcium gluconate takes priority over the insulin and sugar.

11:52 And lastly Answer choice E, which is IV sodium bicarbonate, well, that would be true because this patient is going to have metabolic acidosis and giving sodium bicarbonate can reverse that but that requires actually getting a laboratory value to reverse the acidosis not as critical as waiting and preventing fatal cardiac arrhythmias with IV calcium gluconate.

12:17 Okay, let’s review some high-yield information for this question. Now, let’s first talk about end- stage renal disease.

12:25 Now, as the name implies, end-stage, which means the last stage, really is the final stage of kidney failure so we call it end-stage renal disease.

12:34 Now, that’s defined as having a glomerular filtration rate or GFR less than 15 and what you need when you’re at end-stage renal disease is either hemodialysis or renal transplant.

12:49 Now patients presenting with end-stage renal disease can really present with a wide variety of symptoms.

12:56 People can present with simple fatigue to severe cardiac arrhythmias, poor urine output or even presenting coma, so symptomatology is really quite wide.

13:07 Now, very important to know and this is a common board question, that in the US the most common cause of end-stage renal disease is diabetes.

13:18 Now when you think about diabetes you may think of just high blood sugar or diabetic neuropathy like stocking glove, but also I want you to think of the kidney.

13:27 It’s called diabetic nephropathy meaning the diabetes is affecting the kidney and that’s a very common cause that poor diabetes control can lead to end-stage renal disease.

13:39 And again to really emphasize, if you have a patient who’s on end-stage renal, they are going to require either hemodialysis to be able to use the dialysis machine to function like a kidney and clean the blood and move electrolytes or they’re gonna have to get a renal transplant to get a new kidney.

13:58 Now, another really high-yield topic to talk about is hyperkalemia.

14:03 Now, hyperkalemia is any potassium level above 5.5 but what’s really cool here is we actually split up hyperkalemia into different severities of mild, moderate and severe. Mild being defined as a potassium level of 5.5 to 5.9; moderate being the potassium level of 6.0 to 6.4 and severe being anything greater than 6.5.

14:30 Now, the reason why we care about hyperkalemia is that it has a high risk of cardiac arrhythmia and death, if you have severe hyperkalemia so it’s not benign, it's something that we really worry about, if you recall you can look at an EKG and see peak T waves, and if you have a high potassium level, you’re gonna worry because they can cause a cardiac arrhythmia that can lead to death.

14:57 Now, what are common causes for someone to come in with a elevated potassium level? Now, like we said they could have kidney failure, you know, the kidney is not working properly, it’s not getting rid of the potassium, it’s holding on to it so that can be a cause; also hypoaldosteronism -- think of the renin-angio-aldo system.

15:18 Rhabdomyolysis -- rupturing all those muscles cells releasing the intracellular potassium and certain medications like spironolactone, NSAIDs and angiotensin converting enzyme inhibitors.

15:31 Now, again, here the treatment for hyperkalemia really is directed and not only on lowering the potassium level but also maintaining and reversing the cardiac excitability that can cause an arrhythmia.