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16.01 Diuretics (Loop, Potassium Sparing, Thiazide, Furosemide/Lasix)

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  1. Diuretics
    1. Affect reabsorption of fluids electrolytes in the nephrons in the kidneys
      1. Review of the Nephron and what it does
        1. It is the functional unit of the kidney
        2. It has several different parts
          1. Proximal convoluted tubule
            1. 65-70% of sodium is reabsorbed here
            2. Diuretics do NOT affect this part of the nephron
          2. Descending loop of Henle
          3. Loop of Henle
          4. Ascending loop of Henle
            1. Na+-K+-2Cl- pump located here
              1. It’s job us to reabsorb Na+, K+ and Cl- back into the blood.
              2. Water follows sodium so water is reabsorbed also
    2. Types of Diuretics
      1. Loop Diuretics
        1. Mechanism of action- inhibits the entire Na+K+2Cl- pump in the ascending loop of Henle
          1. Blocks Na+, K+, CL- and water reabsoprtion from happening
          2. Increases urine output
          3. Na+, K+ and Cl are excreted into the urine
        2. Indications
          1. Edema (Heart Failure, Hepatic failure, Cirrhosis)
          2. Renal disease
          3. Pulmonary edema
          4. Hypertension
        3. Examples
          1. Furosemide (Lasix)
          2. Toesemide
          3. Bumetanide- causes more diuresis than furosemid
      2. Potassium Sparing Diuretics (a weaker diuretic)
        1. Mechanism of action- blocks the affect of aldosterone in the kidney
          1. Allows sodium and water to be excreted (more urine output) and potassium to be reabsorbed.
        2. Indications
          1. Edema (from Heart failure, Liver failure, Cirrhosis)
          2. Pulmonary edema
          3. Hypertension
        3. Examples
          1. Spironolactone
          2. Amiloride
      3. Thiazide Diuretics (not as strong as loop diuretic but stronger than potassium sparing diuretic)
        1. Mechanism of action- blocks the Na+ – Cl- pump in the distal convoluted tubule
          1. Blocks reabsoprtion of Na+ allowing it to be excreted.
          2. Water follows sodium increasing urine output
        2. Indications
          1. Edema (heart failure, hepatic cirrhosis, hepatic failure_
          2. Pulmonary edema
          3. Hypertension
        3. Examples
          1. Chlorothiazide
          2. Hydrochlorothiazide


  1. Diuretics are commonly prescribed to treat edema and hypertension.


  1. Assess for side effects
    1. Loop Diuretic
      1. Hyponatremia
        1. Headaches, weakness, change in LOC, seizures
      2. Hypokalemia
        1. Cardiac arrhythmias, nausea, vomiting, weakness
      3. Hypochloremia
      4. Hypotension
        1. Fainting, dizziness
      5. Diuresis
      6. Dry mouth
      7. Thirst
      8. Ototoxicity- tinnitis (ringing in ears)
    2. Potassium Sparing Diuretic
      1. Hyperkalemia
        1. Cardiac arrhythmias
      2. Metabolic acidosis
      3. Gynecomastia
      4. Diuresis
      5. Dehydration
        1. Dry mouth, thirst, weight loss
    3. Thiazide Diuretic
      1. Hyponatremia
        1. Headaches, weakness, change in LOC, seizures
      2. Hypokalemia
        1. Cardiac arrhythmias, nausea, vomiting, weakness
      3. Hypotension
      4. Hyperglycemia in diabetic patients
      5. Hyperlipidemia
      6. Increased uric acid

Therapeutic Management

  1. Monitor electrolytes closely
  2. Blood pressure should be monitored daily
  3. Prevent orthostatic hypotension by rising slowly from lying, to sitting, to standing.
  4. Monitor for signs of dehydration in patients
    1. Patient may be asked to weigh themselves daily
  5. Contraindications
    1. Thiazide diuretics
      1. Non-steroidal anti-inflammatory medications (aspirin, ibuprofen, ketorolac)

Nursing Concepts

  1. Elimination
    1. Diuretics help treat edema and hypertension by increasing fluid excretion in the kidneys.
  2. Fluid & Electrolyte Balance
    1. Diuretics all affect fluid and electrolytes in the body so it’s important to monitor fluid status and electrolytes very closely.
  3. Perfusion
    1. Diuretics affect perfusion by increasing fluid excretion in the kidneys.
  4. Pharmacology
    1. Diuretics are a medication commonly prescribed to treat edema and hypertension.

Patient Education

  1. When taking a Potassium Sparing Diuretic patients should be instructed to AVOID foods that are high in potassium to prevent hyperkalemia.
  2. When taking Loop Diuretics patients should be instructed to eat foods that are high in potassium to prevent hypokalemia.

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Video Transcript

Diuretics. We gonna cover 3 main types of diuretics, Loop Diuretics, Thiazide Diurectics, and Potassium Sparing Diuretics. All diuretics works on kidney and in especially nephron, which is a functional unit of kidney. We gonna talk in detail about each diuretics mechanism of action or their side effects in which this condition we use in the nursing consideration, okay?

So, let’s talk about first, loop diuretics mechanism of action. Okay, so this is the diagram representing nephron which is the functional unit of kidney and all the blood filtration, formation of urine reabsorption and excretion of all the electrolytes happen in this nephron. However, we are interested in the reabsorption and excretion of sodium, potassium and water. Now, before we go into the mechanism of action of loop diuretic, let’s understand some part of the nephron and where the sodium, water, potassium reabsorption, excretion occurs. So, first of all, proximal convoluted tubules where about 65% – 70% of sodium gets reabsorbed.There’s no diuretic that works in, works here. So, 65 – 70% of sodium gonna get reabsorbed no matter what diuretic we give. However, this is called descending loop of Henle. This is loop of Henle. And, this is ascending loop of Henle. We’re interested in ascending loop of Henle. In ascending loop of Henle, there’s a pump, it’s called Na+-K+-2Cl- Now, this pump, what is does, it uses the energy, uses energy to reabsorb sodium, potassium and chloride back to the blood. Now, when sodium gets reabsorbed, water is gonna follow sodium. So, water is gonna get reabsorbed as well in ascending loop of Henle. Now, here, about 25% approximately, sodium gets reabsorbed using this pump which uses the energy as well. Now, loop diuretic inhibits the whole pump. Loop Diuretic inhibits this whole reabsorption process. When the sodium doesn’t get reabsorbed, potassium doesn’t get reabsorbed, and chloride does not get reabsorbed, water is not gonna get reabsorbed as well. And, when water doesn’t get reabsorbed, if you look right here, this ascending loop of Henle, it’s gonna go to, from here, to the collecting ducts and from there, it’s gonna get excrete through urine. So, sodium, water, and potassium and chloride are all gonna get excreted through the collecting ducts if that gets reabsorbed, since loop diuretic is gonna inhibit the pump.

So, as we understood that mechanism, or action of the loop diuretic, let’s just talk briefly what it does on the nephron and especially more in detail like ascending loop of Henle. And if we know this 3 main mechanism of action of this loop diuretic, we’ll be able to understand this side effects and also the nursing concentration as well. So, it prevents the reabsorption of sodium, water, potassium, and chloride, okay? Now, indication. Because of this, it excretes the water, it can be use for the prevention of edema. We can use this medication to prevent edema that happens in the heart failure, pulmonary edema, hepatic failure or hepatic cirrhosis or chronic renal failure. This medication is also used to treat hypertension, especially, furosemide. Also, we call this one as a Lasix, or water pill. This particular drug, a physician use quite often to treat hypertension as well.

So, next slide, we gonna talk about the side effects, nursing considerations and contraindications. Now, as we talk the mechanism for action, it affects many electrolyte reabsorption in kidney. So, first side effects is electrolyte imbalance. Which the first one, it causes Hyponatremia. Now, when we cover lithium medication which is bipolar medication, we’ll go over why Hyponatremia can cause the lithium toxicity. But like, since this medication can cause hyponatremia, and if a patient on lithium medication for bipolar, that can cause serous lithium toxicity. It can cause, since the hyponatremia, because of the hyponatremia, it can cause a central nervous system changes such as headaches, changes in level of consciousness. So, we have to look for those symptoms as well. Another electrolyte imbalance is hypokalemia. Now, due to the low potassium level, now, normal potassium level is 3.5 to 5.2. Okay, so, usually, if a hypokalemia is lower than 3.5. Now, it can cause cardiac arrthymia and also, the digoxin toxicity. Also, we will talk about digoxin in cardiac glycoside slides. Now, digoxin toxicity can happen when there’s a low potassium level in the body. So, you have to look for the digoxin toxicity as well. And this, finally can cause the hypochloremia which is low chloride level. So, if you go back to the mechanism of action slide and if you look over it, remember, we talked about that it prevents the reabsorption of sodium, potassium and chloride. So, it’s kinda self explanatory that why this medication can cause hyponatremia, hypokalemia and hypochloremia. Now, also as a nurse, if a patient on this medication, you want to monitor the electrolyte, sodium, potassium, chloride, magnesium and calcium. Okay.

This medication also can cause significant hypotension. And, that’s why you have to teach the patient about their side effects. Fainting and Dizziness. And since this drug also excrete significant amount of water, it causes diuresis. You have to teach patient to look for the signs and symptoms like thirst, dry mouth, significant weight loss, low urine output usually less than 30 mL/hour. This medication also can cause ototoxicity and one of the signs of the ototoxicity is tinnitus.

So, you have to look for, which is basically ringing in the ears. Okay, so, what we have to teach patient and what what are the nursing considerations. So, first of all, you have to tell patient to eat high potassium foods because it causes the hypokalemia. Such as bananas, potatoes, o whatever you like with a high potassium containing foods. You have to tell them like monitor for signs and symptoms of hypokalemia such as nausea, vomiting and generalized weakness as well. We have to tell them monitor their blood pressure daily. And, avoid using other ototoxic medications such as gentamicin. This one can cause, this medication can cause sudden change in blood pressure. It can cause a hypotension. We have to educate patient to avoid sudden changes in the position, rising slowly from lying position to sitting, and so forth. They can’t just change their position suddenly because it can cause significant decrease in blood pressure and can cause dizziness.

So, what are the examples of loop diuretic? The first one is furosemide, which is widely used. Toesemide, Bumetanide, and Etacrynic acid. Haven’t seen this medication used quite often in patient. I’ve seen the furosemide and bumetanide because bumetanide is really a string loop diuretic compared to furosemide. So, if they really need a huge amount of diuresis, they prefer to use bumetanide compared to furosemide. So, that’s a nice thing to remember if you’re working on the floor and kinda wondering why they are using bumetanide instead of furosemide, because they need a high amount of diuresis.

Alright, that was about the loop diuretic, we’ll cover thiazide diuretic and potassium sparing diuretics in the next presentation. Thanks for watching.

Potassium sparing diuretics. So, in this module, we’ll talk about the mechanism of action in which disease process we use this potassium sparing diuretic, what are the side effects, and nursing consideration and some of the examples of potassium sparing diuretic. So, as we talk about this potassium sparing diuretic, we gonna talk about, a little bit about loop diuretic and thiazide diuretic in recap. So, about 70% of sodium, 65 – 70% of sodium gets reabsorbed here in the proximal convoluted tubules. Right here, in ascending, about 20 – 25% of sodium gets reabsorbed. And here, in distal convoluted tubules, about approximately 5% sodium gets reabsorbed. So, by the time the urine reaches this yellow collecting ducts, it does have enough sodium to get reabsorbed. I said, enough, that means not enough. Like in proximal convoluted tubules, loop of Henle or distal convoluted tubules. It’s about like remaining approximately 1 to 2 % of sodiums left in the urine to get reabsorbed. That is the reason this potassium sparing diuretic is recur than thiazide diuretic and loop diuretic.

Now, let’s see how the potassium diuretic, potassium sparing diuretic works. Now, we call the aldosterone. We also talked about this aldosterone in RAA System. This aldosterone gets secreted by the adrenal gland. Now, the adrenal gland is right on the top of both kidneys, so, it gets secreted from the adrenal gland. What this aldosterone does in the collecting ducts right here, there’s a pump that’s called Sodium – Potassium (Na+/K+) pump. How does this pump work? If one sodium gets reabsorbed, then one potassium gets excreted in the urine. So, it’s kinda like an exchange. If one sodium gets excreted, then one potassium gets reabsorbed. Now, under the effect of aldosterone, one sodium gets reabsorbed and one molecule of potassium gets excreted in urine. While as we know, one sodium molecule is followed by one molecule of water. So, also, H2O gets reabsorbed and that’s how this aldosterone works in the collecting ducts. What does this potassium diuretic does is it blocks the effect of the aldosterone here in the collecting ducts. So, aldosterone won’t be able to activate this Sodium – Potassium pump in the collecting ducts. Now, when it doesn’t activate, it does the opposite. Sodium gets excreted, also, the water is gonna follow, while potassium will get reabsorbed. So, that’s how it does the diuresis. However, this potassium sparing diuretic doesn’t have much sodium to excrete, about 1 – 2%, and that’s the reason, as we talked, this is weak diuretic than loop diuretic and thiazide diuretic. So, often, you see, these diuretics are given with loop diuretic or thiazide diuretic in order to prevent the hypokalemia done by thiazide and loop diuretic. If you go back and look at the side effects of loop diuretic and thiazide diuretic, one of the main side effect, it causes the hypokalemia. While this one, it increases the potassium reabsorbs. So, this potassium diuretic, potassium sparing diuretics conserves potassium in the body. That’s why they give this loop diuretic and thiazide diuretic with potassium sparing diuretic to contradict the hypokalemia effect of those loop and thiazide diuretic. So, that was it about the mechanism of action. So, if you understood this mechanism of action really good, you’ll be able to tell like what are the side effects and why we use this medication in certain disease.

Mostly, all the diuretics are used to treat edema. To treat edema, that happens in heart failure, pulmonary edema, hepatic failure, hepatic cirrhosis and chronic renal failure. Now, as I talk to you, only loop diuretic works better for, in renal disease. These thiazide diuretic or potassium sparing diuretic doesn’t work well or at all in renal failure. So, you have to remember this crop. Even though I say here like chronic renal failure, it’s not necessarily true that this medication will work if they have a chronic renal failure. Because in order for this medications, especially the thiazide diuretic and potassium sparing diuretic, kidney blood flow has to be good. And most often, chronic renal failure did not have a really good blood flow because their nephrons and the structure of the kidneys, they are already damaged. While the loop diuretic, as I said here, doesn’t require that good kidney blood flow in our, to produce diuretic. So, we can use this one in chronic renal failure as well. So, if someone has a chronic renal failure, they’d still give this potassium sparing diuretic but in conjunction with loop diuretic in order to contradict this loop diuretic hypokalemia side effects. And also, this medication is often used to treat hypertension as well.

Alright, so, what are the side effects? So, as you’ve understood mechanism of action, it reabsorbs the potassium back to the body by inhibiting the Sodium – Potassium pump and aldosterone. This can cause the hyperkalemia. Now, what are the signs and symptoms you may see if a patient has a hyperkalemia? It’s cardiac arrythmia, which can be any kind of cardiac arrythmia because potassium level is really important for the heart rhythm to be in a sinus rhythm. Now, also, if you look at the ACE inhibitors, and ARBs inhibitor videos, you will see that one of the side effects these two classes has is, and also the Renin antagonist, is hyperkalemia. So, if you are, a patient is on ACE inhibitors, or ARBs or Renin antagonist, and if a physician put a patient on potassium sparing diuretic, it can cause really lethal hyperkalemia. The normal level of potassium is 3.5 to 5.2 and this potassium level can really go up, like really, because there are like multiple drugs the patient is on that causes hyperkalemia. And also, you need to teach patient to avoid taking potassium rich food when they are on potassium sparing diuretic. Now, this drug also causes metabolic acidosis and also gynecomastia. As, you know, this drug produce the diuresis, it can cause dehydration and some of the symptoms of dehydration would be thirst, dry mouth and weight loss.

And these are some examples of the potassium sparing diuretic. There’s another trick to remember these drugs names but they’re like, the first one most often NCLEX use is this, Spironolactone. This drug quite often been tested on NCLEX. Amiloride, Eplerenon, and Triamterene. These are the 4 examples of potassium sparing diuretic. But this is the important one to remember, Spironolactone.

That was it about the potassium sparing diuretic. If you have any question, you can post a comment or contact us. Thank you. Thanks for watching.

Thiazide diurectics. So, in this, when you begin to learn about the mechanism of thiazide diuretics, what are the indications, side effects, and those in consideration. So, as we talk about this whole unit which is called nephron and the functional unit of the kidney, plays a really important part in formation of urine. And the urine formation happens through the reabsorption and excretion of electrolytes including sodium, potassium, chloride, magnesium, calcium and etc. So, for the mechanism of action of thiazide diuretic, we are interested in this distal convoluted tubules, right there, this part. If you watched the previous video of loop diuretic and the mechanism of action, we mentioned like here, which is the proximal convoluted tubules, about 65 – 70% of sodium gets reabsorbed, right there. About here, in the ascending loop of Henle, about approximately 25% of sodium gets reabsorbed. Now, in the distal convoluted tubules, only approximately 5% of sodiums gets reabsorbed. Now, there is a pump, it’s called Sodium – Chloride (Na+ – Cl-) cotransporter. Now, you don’t need to know this Sodium-Chloride cotransporter as a nurse or in NCLEX but this is an easier way to remember the mechanism of action and the side effects as well. Now, since we know every sodium molecule is followed by water, one molecule of water. So, when 5% of sodiums gets reabsorbed back to the kidneys and then back to the blood, about that much, water gets reabsorbed as well. Now, the main mechanism of thiazide diuretic is to block this Sodium – Chloride cotransporter. So, it doesn’t let this cotransporter to reabsorb about 5% of sodium. So, water reabsorption is gonna block as well. So, that’s how water is gonna get through the distal convoluted tubules, and gonna go through the collecting ducts, and gonna excreted through the urine. So, that’s the basic mechanism of action of thiazide diuretic, how it does the diuretic. Now, loop diuretic is stronger than thiazide diuretic. And the reason is, loop diuretic blocks a pump that is responsible for about 25% of sodium reabsorption. So, it actually prevents more reabsorption of water compared to thiazide. Because thiazide is responsible for blocking a pump who’s responsible for about, for reabsorption of sodium for about 5% So, that is the reason loop diuretic are stronger diuretic than thiazide diuretic because of, it blocks the more reabsorption of sodium compared to the thiazide diuretic. And, as we know, each sodium molecule is followed by water. So, that is the main reason.

So, next slide, we’ll see in which disease processes we use this thiazide diuretic. So, mostly, all the diuretics are used for the same purpose. To decrease the fluid overload or to decrease the enema in heart failure, pulmonary edema, hepatic failure, hepatic cirrhosis. And because hepatic failure and hepatic cirrhosis, many patient can develop ascites which is basically a fluid build up in the abdominal cavity. And also, in the chronic renal failure. Now, here’s a little bit difference between the thiazide diuretic and loop diuretic. Since the loop diuretic are really strong, if the kidneys aren’t working properly, then we can still use the loop diuretic to the diuresis. It doesn’t really require good kidney but blood flow in order for loop diuretic to work. However, the thiazide diuretics are really weak that loop diuretic. It requires proper kidney blood flow. So, I would say, here, it can be used in the renal failure but at some extent. If the kidneys aren’t working properly at all, then you can’t really use the thiazide diuretic to produce the diuresis. So, that’s the main difference between loop diuretic and thiazide diuretic as well. You cannot give this medication if they have a kidney failure or the kidneys are not getting blood flow at all. And this medication is also used to treat the hypertension as well.

Now, what are the side effects? The side effects, it can cause the hyponatremia, because it’s gonna prevent the reabsorption of 5% of the sodium in nephron. However, it’s only 5% so it doesn’t cause significant hyponatremia if you compare with loop diuretic, but still can cause the hyponatremia. So you really can, want to watch the patient for lithium toxicity if they are in lithium drug. Lithium drug is usually used for bipolar, okay. And also, you have to look for the central nervous system changes like headache and level of consciousness changes as well. Now, these can, these drugs can cause also hypokalemia. Now, remember, any kind of diuretic can cause electrolyte imbalance since it works by reabsorption, it works by preventing reabsorption of electrolytes, basically, sodium, chloride, potassium and all. So, electrolyte imbalance is a really common side effect you can see in a patient who’s on diuresis, who’s on diuretic medication. Now, it can cause a hypokalemia, so, you have to look for the hypokalemia symptoms which are nausea, vomiting and generalized weakness and it can cause a cardiac arrhythmia if the level goes below 3.5. The normal level of potassium is 3.5 – 5.2. So, if it goes below 3.5, it can cause cardiac arrhythmia. And also, we’ll talk about digoxin toxicity, digoxin medication which is a cardiac glycoside. Now, if potassium goes below 3.5, it can cause digoxin toxicity as well.

Now, these drugs can also cause hypotension. And the signs and symptoms that we look for is fainting and dizziness. Now, you have to teach the patient as well like this drug can cause significant hypotension, they need to be really be careful when they get up. They don’t wanna really get up suddenly if they’re lying down, they want to rise slowly, instead of suddenly getting up. That can cause significant orthostatic hypotension and it can produce fainting and dizziness and then they can fall. As a nurse, you need to educate the patient about these side effects as well. This medication causes diuresis, it can cause dehydration, and the signs and symptoms are thirst, dry mouth, weight loss and low urine output. And you want to teach patient. If your urine output is significantly low, then, notify physician. And if patient is on the hospital and then, as a nurse, you wanna look for at least urine output of about 30 mL/hour. Now, these drugs can also cause the hyperglycemia in diabetic patients. So, you really want to tell patient who’s a diabetes and if they are on insulin or any kind of anti-diabetic medication to check their blood glucose level quite frequently in order to make sure that they don’t get the hyperglycemia. And this drug can also increase the LDL level and uric acid level. Now, so this one can cause hyperlipidemia, and this one can cause a significant problem in a patient who has a gout. Now, if you’re familiar with the disease gout, in gout, the uric acid level goes up and that uric acid deposit in the joints, ball joints, especially the fingers, like small joints present in the finger, like that. It causes pain. Since this patient who has a gout already increase uric acid level, and on top of that, these drugs can also increase the uric acid level, you need to be really careful if you are prescribing, if the patient is on this medication for gout and if the patient already has a gout.

Okay. And, interaction for thiazide diuretic. So, nonsteroidal anti inflammatory medications such as aspirin, ibuprofen, ketorolac, indomethacin, and those nonsteroidal anti inflammatory drug can decrease the thiazide diuretic efficacy. So, they can actually causes, if you’re giving this medication to treat edema and everything, it’s not gonna cause, it’s not gonna diuresis patient the way it should and it’s gonna decrease the efficacy of this thiazide diuretic drugs. Now, beta blocker can also cause hyperglycemia and hyperlipidemia. So, if patient is on beta blocker, and also on this thiazide diuretic, then they can develop more hypeglycemia and hyperlipidemia, so you wanna watch for that too.

One of the examples of these drugs, chlorothiazide, hydrochlorothiazide. So, if you see the examples in this one, like mostly, drugs have thiazide at the end of name, not all of them, so be careful. Like this chlorothalidone, this methyclothiazide, this has thiazide, while these 3 drugs, this one also has a thiazide but these 2 drugs doesn’t have a thiazide. But however, most NCLEX question gonna be ask about the hydrochlorothiazide and it can also be called an HCT, just for your information. So, the hydrochlorothiazide has been tested very often.

So, that was all about the thiazide diuretic. If you have any questions about thiazide diuretics, you can contact us. In the next video, we’ll cover the potassium sparing diuretic. Thank you.

  • Question 1 of 1

A 67-year-old client with renal dysfunction has received a prescription for hydrochlorothiazide (Hydrodiuril) tablets. Which condition is considered a contraindication for using this drug?

Module 0 – Pharmacology Course Introduction
Module 3 – Disease Specific Medications

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