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Pharmacology · chapter 5 · Fluids and Electrolytes, Vitamins, Minerals, and Alternative Therapies

Electrolytes

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. Therapeutic serum potassium

    Therapeutic serum potassium levels are 3.6 to 5.4 mEq/L (Shrimanker Bhattarai, 2023).

  2. Acid–base shifts move potassium

    The levels of potassium in the body are influenced by acid–base imbalances. Acidotic conditions can lead to the movement of potassium out of cells, whereas alkalotic conditions can promote movement of potassium into cells.

  3. Hyperkalemia on the ECG

    Electrocardiogram (ECG, EKG) changes such as peaked T waves, flattened P waves, and prolonged QRS durations may be seen. In severe cases, hyperkalemia can cause cardiac arrest (Shrimanker Bhattarai, 2023).

  4. Teaching for hyperkalemia

    Clients should avoid food high in potassium (such as bananas, potatoes, and spinach), avoid salt substitutes (as these are high in potassium), take drugs as prescribed, and seek medical attention if they develop manifestations of hyperkalemia, such as palpitations, tachycardia, and muscle weakness.

  5. Hypokalemia signs and ECG changes

    Manifestations of hypokalemia include fatigue, muscle weakness, muscle cramps, constipation, and irregular heartbeat. EKG changes may be present with T wave inversion, widespread ST depression, and prominent U waves (Shrimanker Bhattarai, 2023).

  6. Potassium supplement interactions

    Potassium supplements should be used cautiously with ARBs, ACE inhibitors, and potassium-sparing diuretics such as spironolactone.

  7. Never push IV potassium

    Rapid administration of potassium via intravenous bolus or push can result in cardiac dysrhythmias and client death.

  8. Watch the IV site with potassium

    Clinical Tip Potassium Administration and IV Site Assessment Monitor the client’s IV site closely when administering potassium intravenously for infiltration because potassium solutions can cause extravasation and tissue necrosis if they infiltrate into subcutaneous tissues. Discontinue the IV fluids immediately if this occurs and notify the health care provider.

  9. Hypernatremia signs

    Manifestations of hypernatremia include thirst, dry mucous membranes, flushed dry skin, elevated body temperature, muscle twitching, seizure, and coma.

  10. Hyponatremia signs

    Manifestations of hyponatremia include muscle weakness, decreased deep tendon reflexes, headache, lethargy, confusion, weak or thready pulse, decreased blood pressure, seizures, and coma.

  11. Calcium supplement interactions

    Calcium supplements should be used cautiously with levothyroxine, tetracycline antibiotics, and quinolone antibiotics because they can decrease their absorption.

  12. Separate iron from calcium

    Clinical Tip Calcium Supplements and Iron Administration Avoid administering oral iron supplements within 1 to 2 hours of oral calcium supplements and dairy products because calcium may interfere with the absorption of iron and reduce its effectiveness (Piskin et al., 2022).

  13. Magnesium and potassium move together

    Magnesium and potassium have an interdependent relationship; when potassium levels decrease, so do magnesium levels, and vice versa.

  14. Hypermagnesemia signs and treatment

    Manifestations of hypermagnesemia include weakness, lethargy, confusion, low blood pressure, and in severe cases, cardiac arrest. Treatment of hypermagnesemia consists of removing the cause of excess magnesium, administering drugs such as calcium gluconate to reduce magnesium in the body, and symptom management.

Terms to know

Hyperkalemia
Hyperkalemia Hyperkalemia is a condition where the level of potassium in the blood is higher than normal (usually above 5.5 mEq/L) (Shrimanker Bhattarai, 2023).
Hypokalemia
Hypokalemia Hypokalemia is a condition where the level of potassium in the blood is lower than normal (less than 3.6 mEq/L).
Hypernatremia
Hypernatremia Hypernatremia is a condition in which the sodium levels in the blood are higher than normal (above 145 mEq/L).
Hyponatremia
Hyponatremia Hyponatremia is a condition in which sodium levels are lower than normal (less than 135 mEq/L).
Hypocalcemia
Hypocalcemia Hypocalcemia is a condition in which serum calcium levels are lower than normal (lower than 8.8 mg/dL) (Drake Gupta, 2022).
Hypomagnesemia
Hypomagnesemia Hypomagnesemia refers to low levels of magnesium in the blood (less than 1.46 mEq/L).

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 with hypokalemia has an order for intravenous potassium chloride. A new nurse plans to give it as an IV push to correct the level faster. What should the precepting nurse say?

    1. Potassium must never be given by IV push or bolus because it can cause dysrhythmias and death.
    2. Give the push slowly over one minute.
    3. IV push is safe through a central line only.
    4. IV push is fine if the dose is small.

    Answer: Potassium must never be given by IV push or bolus because it can cause dysrhythmias and death.

    Potassium is never pushed or bolused intravenously; rapid administration can cause cardiac dysrhythmias and client death. Premixed diluted solutions are used to reduce errors, so no version of a push is acceptable.

  2. A client receiving IV potassium reports burning at the peripheral IV site, and the nurse sees swelling around it. What is the nurse's priority action?

    1. Flush the line with normal saline.
    2. Apply a warm pack and continue the infusion.
    3. Stop the IV fluids immediately and notify the health care provider.
    4. Slow the infusion and recheck in an hour.

    Answer: Stop the IV fluids immediately and notify the health care provider.

    Potassium solutions can cause extravasation and tissue necrosis if they infiltrate, so the IV fluids are discontinued immediately and the provider is notified. Slowing, continuing or flushing keeps drug going into the tissue.

  3. A client with kidney failure has hyperkalemia. Which instructions should the nurse include in teaching? Select all that apply.

    1. Seek care for palpitations or muscle weakness.
    2. Avoid salt substitutes.
    3. Take a potassium supplement daily.
    4. Limit bananas, potatoes, and spinach.
    5. Use salt substitutes instead of table salt.

    Answer: Seek care for palpitations or muscle weakness., Avoid salt substitutes., Limit bananas, potatoes, and spinach.

    Clients with hyperkalemia should avoid high-potassium foods such as bananas, potatoes and spinach, avoid salt substitutes because they are high in potassium, and seek care for palpitations, tachycardia and muscle weakness. Potassium supplements and salt substitutes would raise potassium further.

  4. A client takes levothyroxine and has just been prescribed a calcium supplement for hypocalcemia. What should the nurse keep in mind?

    1. Calcium increases levothyroxine absorption.
    2. The two drugs have no interaction.
    3. Calcium can decrease the absorption of levothyroxine, so they are used cautiously together.
    4. Levothyroxine must be stopped while taking calcium.

    Answer: Calcium can decrease the absorption of levothyroxine, so they are used cautiously together.

    Calcium supplements are used cautiously with levothyroxine, tetracyclines and quinolones because calcium can decrease their absorption. Nothing in the section says levothyroxine must be stopped or that absorption increases.

  5. A client's serum potassium is 3.1 mEq/L. Which findings would the nurse expect? Select all that apply.

    1. Peaked T waves
    2. Prominent U waves
    3. Muscle weakness
    4. Constipation
    5. Irregular heartbeat

    Answer: Prominent U waves, Muscle weakness, Constipation, Irregular heartbeat

    A level below 3.6 mEq/L is hypokalemia, which causes fatigue, muscle weakness, cramps, constipation and irregular heartbeat, with T wave inversion, ST depression and prominent U waves. Peaked T waves are an ECG change of hyperkalemia.

  6. A client with hypomagnesemia is also found to have a low potassium level. Why should the nurse expect these to occur together?

    1. Potassium supplements lower magnesium.
    2. Low magnesium always causes high potassium.
    3. They are unrelated findings.
    4. Magnesium and potassium levels rise and fall together.

    Answer: Magnesium and potassium levels rise and fall together.

    Magnesium and potassium have an interdependent relationship: when potassium decreases, magnesium decreases too, and vice versa. The other options contradict that relationship or are not in the section.

Where every quote comes from

Section 5.2 Electrolytes 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.