Electrolyte Management in Critical Care Practice Questions
15 free Electrolyte Management in Critical Care practice questions for the NCLEX Exam. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
In a patient with acute kidney injury and rising serum potassium in the ICU, the first priority intervention is to:
- A Administer oral potassium binders only
- B Begin insulin plus glucose with ECG monitoring
- C Restrict dietary potassium and observe overnight
- D Give a large infusion of 0.9% NaCl
Correct answer: Begin insulin plus glucose with ECG monitoring
In acute hyperkalemia with ECG changes, the priority is shifting potassium intracellularly (e.g., insulin + glucose) while monitoring the heart.
Which electrolyte pairing in critically ill patients exemplifies the concept of one imbalance facilitating correction of another?
- A Correcting hypernatremia leads directly to resolution of coexisting hypocalcemia
- B Correcting hypomagnesemia helps fix refractory hypokalemia
- C Correcting hypercalcemia immediately normalizes coexisting hyponatremia
- D Correcting hyperphosphatemia reliably fixes associated hyperkalemia
Correct answer: Correcting hypomagnesemia helps fix refractory hypokalemia
Hypomagnesemia often complicates or causes refractory hypokalemia; correcting magnesium helps restore potassium balance.
What should be the main goal when managing hyponatremia (serum sodium 122 mEq/L) in a patient without neurologic symptoms in the ICU?
- A Raise serum sodium rapidly by more than 10 mEq/L within 24 hours
- B Correct sodium slowly, treat the underlying cause, and monitor
- C Administer hypertonic saline immediately using a bolus protocol
- D Ignore the sodium level and focus exclusively on fluid status
Correct answer: Correct sodium slowly, treat the underlying cause, and monitor
In critically ill patients, sodium abnormalities should be corrected gradually, underlying causes addressed, and frequent monitoring done to avoid complications.
In an ICU patient receiving continuous renal replacement therapy (CRRT), which electrolyte must be vigilantly monitored due to an increased risk of imbalance?
- A Chloride and bicarbonate only
- B Potassium and magnesium
- C Vitamin D and parathyroid hormone
- D Sodium and chloride exclusively
Correct answer: Potassium and magnesium
Critical care patients on CRRT are at higher risk for multiple electrolyte abnormalities including potassium and magnesium, which require prompt recognition and replacement.
What is the appropriate management for a critical care patient with severe hypocalcemia and signs of tetany and QT prolongation?
- A Oral calcium supplementation alone is sufficient here
- B Give IV calcium with ECG and albumin monitoring
- C No action is needed unless calcium falls below 6.0 mg/dL
- D Magnesium status can be safely ignored in this setting
Correct answer: Give IV calcium with ECG and albumin monitoring
In ICU settings, symptomatic hypocalcemia with cardiac/neuromuscular signs requires IV calcium and ECG monitoring; albumin correction should also be considered.
What is the correct management approach for a patient with low serum magnesium (0.9 mg/dL) in the ICU?
- A Wait for symptoms to appear before starting replacement
- B Replace magnesium promptly, as low levels worsen ICU outcomes
- C Magnesium replacement is never necessary in ICU patients
- D Only oral magnesium should ever be used in the ICU
Correct answer: Replace magnesium promptly, as low levels worsen ICU outcomes
Hypomagnesemia is common in ICU and is associated with worse outcomes, so monitoring and timely replacement is important.
What is the appropriate monitoring essential in the hours following insulin plus glucose administration for a patient with hyperkalemia in the ICU?
- A Only potassium levels, checked every 24 hours
- B Both blood glucose and potassium every 2-4 hours
- C A single ECG performed once after 12 hours
- D No monitoring is needed once potassium begins to drop
Correct answer: Both blood glucose and potassium every 2-4 hours
Insulin + glucose shifts potassium intracellularly but risks hypoglycemia and rebound hyperkalemia; frequent monitoring of glucose and potassium is necessary.
Why is hypophosphatemia clinically significant in electrolyte management in critically ill patients?
- A Phosphorus has no clinically meaningful systemic effects
- B Severe depletion impairs diaphragm function and ventilator weaning
- C It only affects bone health over the long term
- D It requires no specific intervention in acute care settings
Correct answer: Severe depletion impairs diaphragm function and ventilator weaning
In critical care, hypophosphatemia can cause muscle weakness including respiratory muscles, complicating ventilator weaning and recovery.
What is the most likely underlying cause of persistent hypokalemia in an ICU patient despite potassium chloride infusions?
- A Overhydration diluting serum potassium
- B Coexisting hypomagnesemia
- C Hypercalcemia driving renal loss
- D Hyponatremia altering distribution
Correct answer: Coexisting hypomagnesemia
In critical care settings, refractory hypokalemia often occurs when magnesium is low; correcting magnesium is often needed for effective potassium repletion.
Which method is likely to be the most effective for removing potassium in a critically ill patient with renal failure and hyperkalemia?
- A Oral potassium restriction alone
- B Loop diuretics only
- C CRRT or hemodialysis
- D Wait for spontaneous resolution
Correct answer: CRRT or hemodialysis
In critically ill patients with renal failure and hyperkalemia, removal methods like CRRT/hemodialysis are among the most effective for potassium clearance.
Besides monitoring sodium itself, what other electrolyte must be monitored when correcting sodium in an ICU patient that influences sodium homeostasis?
- A Potassium
- B Chloride exclusively
- C Albumin only
- D Vitamin D
Correct answer: Potassium
Potassium status influences sodium homeostasis, and in critical care settings multiple electrolyte imbalances interplay, so potassium must be monitored along with sodium.
What therapeutic action is appropriate for a critically ill patient with severe hypomagnesemia and refractory ventricular arrhythmias in the ICU?
- A Ignore magnesium and aggressively treat potassium instead
- B Give IV magnesium sulfate with ECG monitoring
- C Provide oral magnesium tablets as the sole therapy
- D Replace calcium rather than magnesium in this patient
Correct answer: Give IV magnesium sulfate with ECG monitoring
In critical care, severe hypomagnesemia with arrhythmias warrants IV magnesium sulfate under monitoring to stabilise cardiac rhythm.
What must be considered when correcting hypernatremia in a critical care unit?
- A Hypotonic fluids may always be given without any monitoring
- B Limit sodium reduction to about 10-12 mEq/L per 24 hours
- C Rapid correction reliably shortens overall ICU length of stay
- D Only enteral sodium restriction is required for correction
Correct answer: Limit sodium reduction to about 10-12 mEq/L per 24 hours
In ICU settings, rapid correction of hypernatremia risks cerebral edema; hence careful, gradual correction is required.
What should the nurse do if a mechanically ventilated ICU patient with hypophosphatemia experiences respiratory muscle weakness, hemolysis, and impaired ATP generation?
- A Stop all nutrition support immediately and reassess
- B Replace phosphate, as depletion impairs respiratory muscle and ATP
- C Ignore phosphate because the level will self-correct quickly
- D Give hypertonic saline to address the weakness
Correct answer: Replace phosphate, as depletion impairs respiratory muscle and ATP
Hypophosphatemia impairs ATP generation and respiratory muscle (including diaphragm) contractility and can cause hemolysis; the nurse should check and replace phosphate to restore muscle and cellular energy function.
In critically ill patients, what is one key principle regarding electrolyte corrections in the ICU setting?
- A Use standard replacement doses regardless of organ status
- B Individualize replacement for organ dysfunction and ongoing losses
- C Always correct every electrolyte as rapidly as possible
- D Replace electrolytes only once the patient becomes symptomatic
Correct answer: Individualize replacement for organ dysfunction and ongoing losses
In ICU settings, patients have complex physiology, organ dysfunction and multiple imbalances; replacement must be individualized with frequent monitoring rather than a one-size-fits-all.