Hyperkalemia and Electrolyte Emergencies in Kidney Failure Practice Questions

25 multiple-choice questions on Hyperkalemia and electrolyte emergencies in kidney failure for paramedic and EMT students, from Chapter 22 (Genitourinary and Renal Emergencies). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. In a hyperkalemic patient with symptomatic bradycardia, transcutaneous pacing may fail mainly because:

   1. A. Potassium lowers the threshold
   2. B. The pads cannot sense the underlying rhythm
   3. C. High potassium raises the threshold
   4. D. Pacing worsens the hyperkalemia
   Show answer

   Answer: C. High potassium raises the threshold

   Hyperkalemia depolarizes the myocardium and raises the energy needed for capture, so pacing and atropine may fail. IV calcium and potassium-shifting treatment are needed to restore responsiveness. Pacing does not raise the potassium further, and the pads can capture whether or not they sense the rhythm.

2. As potassium continues to rise beyond the stage of peaked T waves, which ECG change typically follows?

   1. A. P waves flatten and the PR lengthens
   2. B. The QT interval becomes very long
   3. C. Prominent U waves appear
   4. D. Delta waves appear just before the QRS
   Show answer

   Answer: A. P waves flatten and the PR lengthens

   Progressive hyperkalemia flattens and then abolishes P waves and lengthens the PR interval, then widens the QRS toward a sine wave. U waves and a long QT are features of hypokalemia, and delta waves suggest WPW.

3. Which ECG pattern suggests life-threatening hyperkalemia?

   1. A. Narrow QRS with tall, peaked P waves
   2. B. Prolonged QT with U waves
   3. C. ST elevation in II, III, aVF
   4. D. Wide QRS merging to a sine wave
   Show answer

   Answer: D. Wide QRS merging to a sine wave

   A sine-wave pattern means arrest is imminent. Treat immediately per protocol.

4. The membrane-stabilizing effect of a dose of IV calcium in hyperkalemia lasts about:

   1. A. 5 to 10 seconds
   2. B. 30 to 60 minutes
   3. C. 24 hours
   4. D. Several days or longer
   Show answer

   Answer: B. 30 to 60 minutes

   Calcium starts working within minutes but wears off in about 30 to 60 minutes and does not lower potassium, so repeat doses and potassium-shifting or removal therapies are needed, especially on long transports.

5. Furosemide is unlikely to lower potassium in an anuric dialysis patient because:

   1. A. It binds potassium in the gut
   2. B. It is cleared by each dialysis
   3. C. His kidneys cannot respond
   4. D. It shifts potassium out of cells
   Show answer

   Answer: C. His kidneys cannot respond

   Loop diuretics remove potassium in the urine, so they need working kidneys. In patients who make little or no urine, dialysis is the only reliable way to remove potassium. Furosemide does not bind potassium in the gut or push it out of cells, and dialysis is not why it fails.

6. In the hospital, sodium zirconium cyclosilicate or patiromer lowers potassium by:

   1. A. Binding potassium in the gut
   2. B. Shifting potassium into cells
   3. C. Stabilizing heart cell membranes
   4. D. Making the kidneys excrete sodium
   Show answer

   Answer: A. Binding potassium in the gut

   These newer oral binders trap potassium in the GI tract so it leaves in the stool. They act over hours, so calcium and shifting agents are still needed for immediate cardiac protection.

7. The only definitive way to remove potassium from a patient with ESRD is:

   1. A. Calcium
   2. B. Albuterol
   3. C. Insulin
   4. D. Dialysis
   Show answer

   Answer: D. Dialysis

   Calcium, albuterol, and insulin are temporary. Dialysis removes potassium from the body.

8. Severe hyperkalemia can cause ST elevation on the ECG that mimics:

   1. A. Normal early repolarization
   2. B. An acute myocardial infarction
   3. C. A first-degree heart block
   4. D. Atrial flutter waves on the baseline
   Show answer

   Answer: B. An acute myocardial infarction

   Hyperkalemia can produce ST elevation and a Brugada-like pattern that resembles STEMI, so in a dialysis patient consider potassium before activating the cath lab. The pattern resolves with treatment.

9. A blood sample that was hemolyzed during collection can make the potassium level appear:

   1. A. Falsely high
   2. B. Falsely low
   3. C. Exactly normal
   4. D. Impossible to read
   Show answer

   Answer: A. Falsely high

   Red cells contain a lot of potassium, so hemolysis during a difficult draw releases it into the sample, causing pseudohyperkalemia. Correlate with the ECG and repeat the test.

10. Which food is very high in potassium and often restricted in kidney failure?

    1. A. White rice
    2. B. Apples
    3. C. Bananas
    4. D. Bread
    Show answer

    Answer: C. Bananas

    Bananas, oranges, potatoes, and tomatoes are high in potassium. Dialysis patients often limit them.

11. A CKD patient started using a salt substitute to cut down on sodium. This product can be dangerous because it contains:

    1. A. Calcium carbonate
    2. B. Magnesium sulfate
    3. C. Sodium bicarbonate
    4. D. Potassium chloride
    Show answer

    Answer: D. Potassium chloride

    Most salt substitutes replace sodium chloride with potassium chloride, which can cause severe hyperkalemia in patients with kidney disease or those taking ACE inhibitors or potassium-sparing diuretics.

12. Right after a dialysis session, a patient has palpitations and frequent PVCs. Besides cardiac disease, consider:

    1. A. Low potassium after dialysis
    2. B. High potassium from the session
    3. C. Too much sodium in the diet
    4. D. Hyperglycemia from the dialysate
    Show answer

    Answer: A. Low potassium after dialysis

    Dialysis removes potassium rapidly, so levels may be low right after a session and predispose to dysrhythmias. Ask when the last session ended and what type of rhythm problem is occurring.

13. Dialysis patients take phosphate binders such as sevelamer with meals to:

    1. A. Raise their potassium levels
    2. B. Lower phosphate absorbed from food
    3. C. Increase their urine output
    4. D. Lower their blood glucose after eating
    Show answer

    Answer: B. Lower phosphate absorbed from food

    Failing kidneys cannot excrete phosphate, and high phosphate binds calcium and causes bone and vascular disease. Binders taken with meals reduce gut absorption of dietary phosphate.

14. Which antibiotic is known to raise potassium, especially in patients with kidney disease?

    1. A. Amoxicillin
    2. B. Azithromycin
    3. C. Doxycycline hyclate
    4. D. Trimethoprim-sulfa
    Show answer

    Answer: D. Trimethoprim-sulfa

    Trimethoprim blocks sodium channels in the distal nephron in a way similar to amiloride, reducing potassium excretion and causing hyperkalemia, particularly in older adults, CKD, and those on ACE inhibitors.

15. A hypotensive dialysis patient has clear lungs and needs IV fluid. The best approach is:

    1. A. A 2-liter bolus as fast as possible
    2. B. No fluid; dialysis patients cannot get any
    3. C. Small boluses with frequent lung checks
    4. D. Oral fluids instead of IV fluids
    Show answer

    Answer: C. Small boluses with frequent lung checks

    Dialysis patients cannot excrete excess fluid, so give small boluses (for example 250 mL) and reassess lung sounds, SpO2, and work of breathing after each. Withholding needed fluid in shock is also harmful.

16. A dialysis patient's 'dry weight' refers to his:

    1. A. Weight before he started dialysis
    2. B. Target weight after fluid removal
    3. C. Weight without clothing on
    4. D. Lowest weight ever recorded
    Show answer

    Answer: B. Target weight after fluid removal

    Dry weight is the weight at which excess fluid has been removed without causing hypotension. Comparing current weight with dry weight helps estimate fluid overload, for example 4 kg above dry weight equals about 4 liters of extra fluid.

17. Sodium bicarbonate in hyperkalemia works by:

    1. A. Shifting potassium into cells
    2. B. Stabilizing the cardiac membrane
    3. C. Removing potassium in stool
    4. D. Increasing glucose
    Show answer

    Answer: A. Shifting potassium into cells

    Raising blood pH drives potassium into cells. It is most helpful when acidosis is present.

18. Insulin is cleared partly by the kidneys. In a patient with advanced CKD, this means insulin:

    1. A. Has no effect on blood sugar
    2. B. Is needed in much higher doses
    3. C. Lasts longer, risking hypoglycemia
    4. D. Raises the potassium level in the blood
    Show answer

    Answer: C. Lasts longer, risking hypoglycemia

    Reduced kidney clearance prolongs insulin's action, so patients with CKD on insulin (or sulfonylureas) are at higher risk of prolonged hypoglycemia. Check glucose in any altered dialysis patient.

19. Why should cardiac monitoring continue after hyperkalemia treatment?

    1. A. Calcium lowers the potassium level
    2. B. Albuterol removes potassium from the body
    3. C. Insulin raises potassium
    4. D. Potassium may rise again
    Show answer

    Answer: D. Potassium may rise again

    Temporary treatments wear off. Potassium may rebound until dialysis is done. Calcium steadies the heart without lowering potassium, and albuterol and insulin shift potassium into cells instead of removing it.

20. Many patients with dangerously high potassium have:

    1. A. Severe itching of the skin
    2. B. A high fever and chills
    3. C. Bright red facial flushing
    4. D. Few or no warning symptoms
    Show answer

    Answer: D. Few or no warning symptoms

    Hyperkalemia often causes no symptoms, or only vague weakness, until a dysrhythmia or arrest occurs, so the ECG and history (missed dialysis, new drugs) are more useful than symptoms.

21. Which is a sign of hypermagnesemia, seen in kidney failure with magnesium-containing laxatives?

    1. A. Hyperactive reflexes
    2. B. Weakness, low reflexes
    3. C. Tremors and seizure activity
    4. D. Tachycardia
    Show answer

    Answer: B. Weakness, low reflexes

    High magnesium depresses nerve and muscle function, causing weakness, hypotension, and respiratory depression.

22. Sodium bicarbonate is most likely to help lower potassium in a hyperkalemic patient who:

    1. A. Also has metabolic acidosis
    2. B. Has a normal blood pH
    3. C. Has high blood pressure
    4. D. Has a fever from an infection
    Show answer

    Answer: A. Also has metabolic acidosis

    Bicarbonate shifts potassium into cells mainly by correcting acidosis, so its benefit is greatest when the patient is acidotic. In patients with a normal pH, it has little effect on potassium.

23. Which ECG finding in a dialysis patient is the strongest sign that hyperkalemia needs treatment now?

    1. A. Prominent U waves
    2. B. A prolonged QT interval
    3. C. A widening QRS complex
    4. D. A heart rate of 88
    Show answer

    Answer: C. A widening QRS complex

    Widening of the QRS signals severe conduction slowing and imminent risk of a sine-wave rhythm or arrest, and calls for immediate IV calcium. U waves and a long QT suggest low potassium or calcium, and a normal rate is not specific.

24. After 2 days of vomiting, a dialysis patient who takes insulin is confused. Your first bedside check should be the:

    1. A. Temperature
    2. B. Blood glucose
    3. C. Pupil size
    4. D. Capillary refill
    Show answer

    Answer: B. Blood glucose

    Altered mental status in an insulin-treated dialysis patient demands an immediate glucose check, because poor intake and slower insulin clearance make hypoglycemia likely. Then consider hyperkalemia, uremia, and infection.

25. Which symptom often accompanies hyperkalemia?

    1. A. Hyperactivity
    2. B. Severe skin itching
    3. C. Muscle weakness
    4. D. Fever
    Show answer

    Answer: C. Muscle weakness

    High potassium affects muscle function, causing weakness and sometimes paralysis.