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Pharmacology · chapter 34 · Diuretic Drugs

Thiazide and Thiazide-Like 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. First-line for hypertension

    They are considered first-line therapies for hypertension, although their antihypertensive effects are not well understood.

  2. Three major properties

    Thiazide and thiazide-like diuretics have three major properties: inhibition of sodium reabsorption, increased reabsorption of calcium, and creation of mild extracellular fluid losses: Thiazide and thiazide-like diuretics inhibit the reabsorption of sodium in the distal convoluted tubule by competing with chloride on the Na-Cl transporter, resulting in the loss of chloride and the passive loss of sodium; however, the therapy decreases reabsorption of only 3%–5% of the sodium in the filtrate.

  3. Calcium is reabsorbed

    Thiazide and thiazide-like diuretics increase the rate of calcium reabsorption in two ways. First, the drugs directly increase the reabsorption rate of calcium that normally occurs in the distal tubule.

  4. Risk of hyponatremia

    Thiazide and thiazide-like diuretics block sodium reabsorption from the distal convoluted tubule; this can result in hyponatremia, which increases water loss.

  5. Metolazone works in chronic renal disease

    Metolazone is a thiazide-like diuretic that, unlike the thiazide drugs, is also effective in chronic renal disease because it does not affect the GFR.

  6. Chlorthalidone lasts long

    Chlorthalidone is a thiazide-like diuretic with prolonged action (48–72 hours).

  7. List of adverse effects

    Adverse effects include metabolic alkalosis, hypercalcemia, hyperglycemia, hyperuricemia, hyperlipidemia, photosensitivity reactions, hyponatremia due to decreased reabsorption, and hypokalemia due to action of the sodium–potassium pump in the distal convoluted tubule.

  8. Photosensitivity and skin cancer

    Their photosensitizing effects also appear to increase the risk of skin cancer (Shin et al., 2019).

  9. Sulfonamide allergy

    Thiazide and thiazide-like diuretics are contraindicated in individuals with sulfonamide allergy.

  10. Signs of a sensitivity reaction

    Reactions can include rash, hives, angioedema, wheezing, and anaphylaxis (Akbari Khorasani-Zedah, 2022).

  11. Digoxin and lithium interactions

    Thiazide and thiazide-like diuretics can increase the risk of digoxin toxicity, and the drugs also should not be administered with lithium.

  12. Renal disease and anuria

    Thiazide and thiazide-like diuretics should be used with caution in clients with renal disease and are contraindicated for clients who are anuric.

  13. Sun protection

    Thiazide diuretics increase the risk for photosensitivity reactions. The client should avoid long periods of sun exposure and should always use sunscreen.

  14. Monitoring the response to treatment

    The nurse should monitor the client’s response to treatment by measuring urine output, monitoring their weight daily, auscultating lung sounds for rales or crackles, and assessing the client’s lower extremities and other dependent areas to determine whether the edema is decreasing.

Terms to know

Hydrochlorothiazide
Hydrochlorothiazide is one of the most commonly used diuretics.
Chlorthalidone
Chlorthalidone is a thiazide-like diuretic with prolonged action (48–72 hours).

Practice questions

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

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Every question here, with the answer

  1. A client taking hydrochlorothiazide works outdoors as a gardener. Which teaching is most important?

    1. Wear sunscreen and avoid long periods of sun exposure.
    2. Take the drug with grapefruit juice.
    3. Avoid all potassium-rich foods.
    4. Double the dose on hot days.

    Answer: Wear sunscreen and avoid long periods of sun exposure.

    Thiazide diuretics increase the risk of photosensitivity reactions and appear to increase skin cancer risk, so clients use sunscreen and avoid long sun exposure. Avoiding all potassium is wrong because thiazides cause potassium loss, and changing the dose is not supported.

  2. Before a first dose of hydrochlorothiazide, the nurse reviews the allergy list. Which allergy is a contraindication?

    1. Latex
    2. Penicillin
    3. Sulfonamide
    4. Shellfish

    Answer: Sulfonamide

    Thiazide and thiazide-like diuretics are contraindicated in clients with a sulfonamide allergy. The other allergies are not named as contraindications in the section.

  3. A client has taken a thiazide diuretic for several months. Which laboratory changes are possible adverse effects? Select all that apply.

    1. Hypocalcemia
    2. Hyperuricemia
    3. Hypokalemia
    4. Hyponatremia
    5. Hyperglycemia

    Answer: Hyperuricemia, Hypokalemia, Hyponatremia, Hyperglycemia

    Thiazide adverse effects include hypokalemia, hyponatremia, hyperglycemia, hyperuricemia, hyperlipidemia and hypercalcemia. Calcium rises, not falls, because thiazides increase calcium reabsorption.

  4. A client takes digoxin and has just been prescribed a thiazide diuretic. What should the nurse monitor for?

    1. Decreased effect of digoxin
    2. Low blood glucose
    3. Signs of digoxin toxicity
    4. Hyperkalemia

    Answer: Signs of digoxin toxicity

    Thiazide and thiazide-like diuretics can increase the risk of digoxin toxicity. They tend to lower potassium and raise glucose, so the other options are not the concern.

  5. A client with heart failure is on a thiazide diuretic for fluid overload. How should the nurse evaluate the response to treatment? Select all that apply.

    1. Measure the client's height weekly.
    2. Auscultate the lungs for crackles.
    3. Measure urine output.
    4. Check dependent areas for decreasing edema.
    5. Weigh the client daily.

    Answer: Auscultate the lungs for crackles., Measure urine output., Check dependent areas for decreasing edema., Weigh the client daily.

    The nurse evaluates response by measuring urine output, daily weights, listening for rales or crackles, and checking whether edema in dependent areas is decreasing. Height does not reflect fluid status.

  6. A client taking a thiazide diuretic develops hives, wheezing and swelling of the lips after a dose. What does the nurse recognise?

    1. Signs of hypokalemia
    2. Photosensitivity from sun exposure
    3. An expected effect of diuresis
    4. A sensitivity reaction that can progress to anaphylaxis

    Answer: A sensitivity reaction that can progress to anaphylaxis

    Sensitivity reactions to thiazides can include rash, hives, angioedema, wheezing and anaphylaxis. These are not expected effects of diuresis or signs of low potassium.

Where every quote comes from

Section 34.5 Thiazide and Thiazide-Like 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.