02.02 Chronic Kidney (Renal) Disease (CKD)

In this lesson we’re going to talk about Chronic Kidney Disease. This is what happens when there is permanent damage to the kidneys and they are unable to recover their normal functions.

CKD is a progressive, irreversible loss of kidney function, usually evidenced by a GFR of less than 60 mL per minute. Normally, GFR should be over 90 mL/min. When that happens, and the kidneys can’t filter the blood, you also lose the ability to remove fluid and toxins, control electrolytes, and regulate acid-base balance. Anything that could affect the vascular system, blood flow to the kidneys, or the kidneys themselves can cause a patient to progress into chronic kidney disease. So that could be diabetes or hypertension, an acute kidney injury that doesn’t get reversed, glomerulonephritis, or even an autoimmune disease like Lupus. These patients will eventually require dialysis because their kidneys aren’t functioning effectively and as they get worse and their GFR drops below 15 mL/min, they’ll progress into what we call End Stage Renal Disease or ESRD.

Now, what we really want you to see is how much the kidneys failing impacts every body system. As we go through these, think about the functions of the kidneys and what happens if they aren’t working. First and foremost, we start to see Azotemia - that’s when those nitrogenous waste products are building up, like BUN, Creatinine, and Urea in the blood stream. And you’ll see how that, alone, causes a number of other issues. In the cardiovascular system, we see volume overload because they aren’t getting rid of the fluid like they should, that causes hypertension and can even lead to CHF if their heart can’t tolerate that kind of preload. We also see a lack of renin production for the renin-angiotensin-aldosterone system, that’s another reason we can see hypertension in these patients. If you need a review on preload and heart failure, head over to the cardiac course. Because of that same volume overload, we can see pulmonary edema - so we’ll hear crackles and they may be short of breath. This volume overload and azotemia can also have neurological effects - we could see cerebral edema or even uremic encephalopathy. Patients could be confused, lethargic, or even slip into a coma. The other thing that affects neurological function is that patients tend to have metabolic acidosis - their kidneys aren’t hanging on to the bicarb like they should, so their pH will drop way low. That can also cause some altered mental status.

Now let’s look at a few other systems. Remember that the kidneys are responsible for making erythropoietin, which goes to the bone marrow to make new blood cells. So patients tend to be anemic and can even be thrombocytopenic, meaning they aren’t making enough platelets either. In the GI system, we see anorexia and nausea and vomiting - these are because of the metabolic acidosis, but also the azotemia. In general it can cause GI discomfort and honestly patients just feel like poo. That excess urea in the blood can also cause some skin symptoms as well. One of the most common is called uremic pruritus - or itching - y’all they get so itchy, I’ve seen a patient scratch themselves til they bled. They can also get something called a uremic frost which is when their skin gets these silvery flakes. We attached an image of this to the lesson, so make sure you check it out. In the musculoskeletal system, we can see osteoporosis and muscle cramps because kidney patients tend to have low calcium levels.

Speaking of electrolytes, we want to make it very clear what happens to four main electrolytes in chronic kidney disease, and really any form of kidney failure. First is the relationship between sodium and potassium. Normally in the kidneys, every time they retain sodium, they excrete potassium. When the kidneys aren’t working, they aren’t able to hold onto the sodium like they usually would, so the sodium gets excreted in the urine - when that happens it reverses the process and retains excessive amounts of potassium. So we see hyperkalemia and hyponatremia. High potassium puts the patient a risk for EKG changes and cardiac abnormalities, while hyponatremia can put them at risk for seizures. Neither are good!

The other set of electrolytes is calcium and phosphate. These also exist in an inverse relationship, as one increases, the other decreases. Normally, the kidneys do an excellent job of excreting phosphate - that helps to ensure calcium levels stay sufficient. The problem in kidney failure is that it doesn’t excrete phosphate like it should. So our phosphate levels get elevated, and in response, our calcium levels get really low. As you’ll learn in the endocrine course - that’s when our parathyroid kicks in and begins breaking down our bones to try to increase the calcium levels. That’s why we see brittle bones and osteoporosis. And of course, hypocalcemia can also cause muscle twitching or cramps.

So you can see how integral the kidneys are in making sure our entire body stays in balance and functions normally. Our entire goal of therapy is going to be to work to restore this balance.

We’re going to end up having to take over the functions of the kidneys since they aren’t working. One of the things we can do is give epoetin alfa, it’s a synthetic form of erythropoietin and can help with anemia. We can also give diuretics to help flush toxins and fluids out of the system But, at some point even the diuretics won’t get the kidneys to do what we want, so we have to resort to dialysis. We’ll talk more about dialysis in a later lesson, but essentially it’s machine like what you see here that pulls the patient’s blood out of their system, runs it through a filter that’s like an artificial kidney - it has a semipermeable membrane and a fluid solution in it that forces all the electrolytes and waste products to diffuse out of the blood. This becomes their lifeline. Many patients get dialysis 3 days a week every week for the rest of their lives. The last thing we see is the most important. We will work on managing and balancing their electrolytes. We give phosphate binders BEFORE meals to keep their phos low...in fact...it’s actually called Phos-Lo. They’ll also get calcium supplements to keep that normal. For potassium, there’s a group of meds that will help to lower potassium - First is kayexelate, that binds it and excretes it in their stool, but it can take a bit of time. So, we give calcium gluconate to help protect the heart while we work on lowering the potassium. The other meds we give are insulin to help drive potassium into the cells so it isn’t in the bloodstream - so we give the patients Dextrose or D50 with it so their sugar doesn’t bottom out. And lastly we give Albuterol - oddly enough, beta agonists can also help shift potassium out of the bloodstream into the cells. Ultimately the goal is to restore that normal balance of electrolytes and do what the kidneys can’t.

So, as you can guess, our top priorities for a patient with CKD are fluid & electrolytes and elimination. But, we also consider safety because patients may experience vision changes or peripheral neuropathy that could put them at risk for falls. They could experience cardiac events because of the high potassium levels, or, if they are receiving dialysis, we need to make sure to keep their dialysis access safe and protected at all times - it’s their lifeline. Check out the care plan attached to this lesson to see more detailed nursing interventions and rationales.

So let’s recap. Chronic Kidney Disease is a condition of progressive, irreversible damage to the kidneys. Ultimately, this is a terminal illness - patients can’t live without functioning kidneys. We’ll see their BUN and Creatinine go up and their GFR drop significantly, in addition to significant electrolyte abnormalities like hyperkalemia and hypocalcemia. Chronic kidney disease affects all systems in the body, but we see the most significant risk to the cardiovascular system - we need to be sure to protect their heart. Eventually, these patients will require dialysis to replace the functions that the kidney can no longer provide. Our nursing priorities are going to be fluid & electrolyte balance, elimination needs, and safety. In a later lesson we’ll talk in a bit more detail about dialysis and how to care for those patients.

So those are the basics of Chronic Kidney Disease. Make sure you check out the care plan, case study, and other resources attached to this lesson to learn more. Now, go out at be your best selves today. And, as always, happy nursing!