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Pharmacology · chapter 19 · Heart Failure Drugs

Diuretics

The 14 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.

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Key points

  1. Potassium-sparing diuretics used sparingly

    Typically, potassium-sparing diuretics, except for mineralocorticoid receptor agonists, are used sparingly in the treatment of heart failure because the combination of ACE inhibitor or ARB with a potassium-sparing diuretic can lead to increased potassium levels.

  2. How loop diuretics work

    Loop Diuretics Loop diuretics block the reabsorption of sodium and chloride in the loop of Henle, which is located in the renal tubule. Due to the way the sodium pump works, loop diuretics also block the reabsorption of potassium.

  3. Loop diuretics are more potent

    Loop diuretics in general are more potent than thiazide diuretics since the majority of sodium and chloride reabsorption occurs in the loop of Henle. Loop diuretics are often the first choice of diuretics in treating heart failure.

  4. Potassium supplements with loop diuretics

    Clients should be informed they may have to take prescribed potassium supplements when taking loop diuretics.

  5. Risk of profound dehydration

    Loop diuretics are potent diuretics that can lead to profound dehydration and electrolyte loss.

  6. Thiazides act in the distal tubule

    Thiazide and Thiazide-Like Diuretics As discussed in Antihypertensive and Antianginal Drugs, thiazide and thiazide-like diuretics block the reabsorption of sodium and chloride in the distal renal tubule.

  7. Thiazides also cause potassium loss

    Due to the nature of sodium reabsorption, thiazide and thiazide-like diuretics cause potassium loss as well as sodium loss.

  8. Who needs caution

    Clients with hypersensitivity to diuretics should not take this classification of drugs. All diuretics should be used with caution in older clients and/or clients with hepatic or renal impairment, arrhythmias, or gout.

  9. Assess electrolytes, glucose and urine output

    Assess the client for electrolyte imbalances and hyperglycemia as well as the client’s urine output. Urine output should be at least 30 mL/hour or 600 mL/24 hours.

  10. Take it in the morning

    Take diuretic earlier in the day (morning) so that diuresis occurs before sleeping times.

  11. Daily weight changes to report

    Report a weight loss or weight gain greater than 2 pounds a day or 5 pounds a week to the health care provider.

  12. Dizziness may mean low blood pressure

    Notify their health care provider about symptoms such as dizziness, lightheadedness, or fainting because these could be related to low blood pressure.

  13. Loop diuretic effects to report

    The client taking a loop diuretic should: Report adverse effects such as dizziness or lightheadedness, fatigue, increased bleeding, tinnitus, weakness, and leg cramps to the provider. Eat potassium-rich foods to replace potassium.

  14. Black box warning for loop diuretics

    FDA Black Box Warning Diuretics Loop diuretics are a potent diuretic and could lead to diuresis with water and electrolyte depletion.

Terms to know

Loop diuretics
Loop Diuretics Loop diuretics block the reabsorption of sodium and chloride in the loop of Henle, which is located in the renal tubule.
thiazide-like diuretics
Thiazide and Thiazide-Like Diuretics As discussed in Antihypertensive and Antianginal Drugs, thiazide and thiazide-like diuretics block the reabsorption of sodium and chloride in the distal renal tubule.

Practice questions

Stuck on select-all-that-apply? How to take them one option at a time.

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  1. A client with heart failure receiving furosemide has had 90 mL of urine output over the last 4 hours. What is the nurse's priority?

    1. Give an extra dose of furosemide.
    2. Document the output as expected for a diuretic.
    3. Recognize that output is below 30 mL/hour and report it to the provider.
    4. Restrict the client's fluids further.

    Answer: Recognize that output is below 30 mL/hour and report it to the provider.

    Urine output should be at least 30 mL/hour; 90 mL in 4 hours is about 22 mL/hour, which is too low and must be reported. Treating it as normal, adding a dose, or restricting fluids does not address the low output.

  2. A nurse is teaching a client who is going home on a loop diuretic for heart failure. Which instructions should the nurse include? Select all that apply.

    1. Eat potassium-rich foods.
    2. Report a weight gain of more than 2 pounds in a day.
    3. Take the diuretic at bedtime so it works overnight.
    4. Take the diuretic in the morning.
    5. Avoid all foods that contain potassium.

    Answer: Eat potassium-rich foods., Report a weight gain of more than 2 pounds in a day., Take the diuretic in the morning.

    Diuretics are taken in the morning so diuresis happens before sleep, weight changes over 2 pounds a day are reported, and clients on loop diuretics eat potassium-rich foods because the drug causes potassium loss. Bedtime dosing and avoiding potassium are the opposite of the teaching.

  3. A client taking furosemide reports leg cramps and weakness. The nurse suspects which electrolyte problem?

    1. High sodium
    2. Low potassium
    3. High potassium
    4. High calcium

    Answer: Low potassium

    Loop diuretics block the reabsorption of potassium, and clients report weakness and leg cramps and eat potassium-rich foods to replace potassium. The drug does not cause high potassium or high sodium.

  4. A client with heart failure takes lisinopril. A nursing student asks why a potassium-sparing diuretic is usually not added. What is the nurse's best answer?

    1. Potassium-sparing diuretics cause severe potassium loss.
    2. They cannot be given by mouth.
    3. Combining an ACE inhibitor with a potassium-sparing diuretic can raise potassium levels.
    4. Potassium-sparing diuretics are more potent than loop diuretics.

    Answer: Combining an ACE inhibitor with a potassium-sparing diuretic can raise potassium levels.

    Potassium-sparing diuretics are used sparingly in heart failure because combining them with an ACE inhibitor or ARB can increase potassium levels. They are not more potent than loop diuretics and do not cause potassium loss.

  5. Which clients need a diuretic used with caution? Select all that apply.

    1. An 84-year-old client
    2. A client with renal impairment
    3. A client with gout
    4. A client with arrhythmias
    5. A healthy 30-year-old client with no other conditions

    Answer: An 84-year-old client, A client with renal impairment, A client with gout, A client with arrhythmias

    Diuretics are used with caution in older clients and in clients with hepatic or renal impairment, arrhythmias, or gout. A healthy adult with no other conditions has none of the listed risks.

  6. A client receiving a loop diuretic reports ringing in the ears. What should the nurse do?

    1. Give the next dose early.
    2. Encourage the client to increase fluid intake to flush the drug.
    3. Report the tinnitus to the provider.
    4. Tell the client this is expected and harmless.

    Answer: Report the tinnitus to the provider.

    Tinnitus is an adverse effect of loop diuretics that clients are taught to report to the provider; ototoxicity and hearing loss are listed adverse effects. Dismissing it or giving more drug ignores a possible sign of ototoxicity.

Where every quote comes from

Section 19.5 Diuretics of Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver, OpenStax, 2024. Read the whole section free at openstax.org.

The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.