Introduction:
Fluid and electrolyte balance plays a vital role in maintaining homeostasis and overall body function. In the NCLEX exam, nurses are frequently tested on their ability to assess, identify, and manage imbalances such as hyponatremia, hyperkalemia, dehydration, and fluid overload. This section provides 100 NCLEX-style Fluid and Electrolytes questions with detailed rationales to help you strengthen your clinical reasoning and test-taking confidence.
Each question mirrors real NCLEX scenarios and includes rationales to enhance your understanding. Let’s begin your high-yield practice session below.
“Whether you’re a U.S. nursing student or an international nurse preparing for NCLEX, mastering fluids and electrolytes is key to passing the NCLEX-RN Exam. You can also practice related topics like NCLEX Pharmacology MCQs and NCLEX Prioritization and Delegation Questions for a complete preparation.”
🩺 NCLEX Fluid and Electrolytes Practice Questions (1–25)
Q1. A patient with heart failure is on furosemide (Lasix). Which electrolyte should be closely monitored?
A. Sodium
B. Potassium
C. Calcium
D. Chloride
Answer: B. Potassium
Rationale: Loop diuretics like furosemide cause significant potassium loss, increasing the risk of hypokalemia.
Q2. A nurse is caring for a patient with hyperkalemia. Which medication helps reduce serum potassium levels?
A. Spironolactone
B. Potassium chloride
C. Kayexalate
D. Magnesium sulfate
Answer: C. Kayexalate
Rationale: Kayexalate (sodium polystyrene sulfonate) promotes potassium excretion through the gastrointestinal tract.
Q3. A patient presents with confusion and muscle weakness. Lab results show sodium level of 125 mEq/L. The nurse identifies this as:
A. Hypernatremia
B. Hyponatremia
C. Hypokalemia
D. Hyperkalemia
Answer: B. Hyponatremia
Rationale: Normal sodium is 135–145 mEq/L; low levels cause neurological symptoms due to cellular swelling.
Q4. Which symptom is expected in a patient with hypernatremia?
A. Bradycardia
B. Muscle weakness
C. Thirst and dry mucous membranes
D. Diarrhea
Answer: C. Thirst and dry mucous membranes
Rationale: Hypernatremia causes cellular dehydration, leading to intense thirst and dry mucosa.
Q5. The nurse is administering IV potassium chloride. Which precaution is essential?
A. Give IV push
B. Administer slowly using a pump
C. Mix with dextrose
D. Give intramuscularly
Answer: B. Administer slowly using a pump
Rationale: Potassium should never be given IV push; rapid infusion may cause fatal cardiac arrest.
Q6. A patient with chronic renal failure is most at risk for which electrolyte imbalance?
A. Hypocalcemia and hyperphosphatemia
B. Hypercalcemia and hypophosphatemia
C. Hyponatremia
D. Hypokalemia
Answer: A. Hypocalcemia and hyperphosphatemia
Rationale: Impaired kidneys cannot excrete phosphate or activate vitamin D, resulting in calcium imbalance.
Q7. Which sign indicates hypocalcemia?
A. Trousseau’s sign
B. Kussmaul’s respirations
C. Flushed skin
D. Lethargy
Answer: A. Trousseau’s sign
Rationale: Hypocalcemia increases neuromuscular excitability, leading to positive Trousseau’s and Chvostek’s signs.
Q8. A nurse monitors for muscle weakness and cardiac arrhythmias in a patient receiving loop diuretics. This is due to:
A. Hypokalemia
B. Hypernatremia
C. Hypercalcemia
D. Hypophosphatemia
Answer: A. Hypokalemia
Rationale: Loop diuretics cause potassium loss, leading to muscle weakness and dysrhythmias.
Q9. A patient receiving isotonic saline (0.9% NaCl) is being treated for:
A. Dehydration
B. Hyponatremia
C. Hyperkalemia
D. Hypocalcemia
Answer: A. Dehydration
Rationale: Isotonic solutions restore extracellular volume without altering electrolyte concentration.
Q10. Which electrolyte imbalance can cause life-threatening cardiac arrest?
A. Hyperkalemia
B. Hyponatremia
C. Hypocalcemia
D. Hypophosphatemia
Answer: A. Hyperkalemia
Rationale: Elevated potassium disrupts cardiac conduction and may lead to asystole.
Q11. Which clinical sign best indicates fluid overload?
A. Weight loss
B. Flat neck veins
C. Crackles in lungs
D. Increased hematocrit
Answer: C. Crackles in lungs
Rationale: Fluid accumulation in lungs produces crackles, indicating pulmonary edema.
Q12. A nurse assesses tenting of the skin and dry lips. These findings indicate:
A. Fluid overload
B. Dehydration
C. Hypercalcemia
D. Hyponatremia
Answer: B. Dehydration
Rationale: Dehydration leads to poor skin turgor and dry mucous membranes.
Q13. In metabolic alkalosis, which electrolyte imbalance is most common?
A. Hypokalemia
B. Hypernatremia
C. Hyperkalemia
D. Hypermagnesemia
Answer: A. Hypokalemia
Rationale: The kidneys excrete potassium in exchange for hydrogen ions, leading to hypokalemia.
Q14. A nurse should question IV administration of lactated Ringer’s in which patient?
A. Dehydrated patient
B. Liver failure patient
C. Postoperative patient
D. Burn patient
Answer: B. Liver failure patient
Rationale: The liver metabolizes lactate; in failure, lactate accumulation may cause acidosis.
Q15. Which condition is associated with muscle cramps and tetany?
A. Hypocalcemia
B. Hyperkalemia
C. Hyponatremia
D. Hyperphosphatemia
Answer: A. Hypocalcemia
Rationale: Calcium deficiency increases neuromuscular excitability, causing muscle spasms.
Q16. The nurse suspects dehydration. Which lab result supports this diagnosis?
A. Low hematocrit
B. Low BUN
C. High hematocrit
D. Low sodium
Answer: C. High hematocrit
Rationale: Dehydration concentrates blood, elevating hematocrit levels.
Q17. Which fluid is best for a patient with hypovolemia?
A. D5W
B. 0.9% Normal saline
C. 3% NaCl
D. 0.45% NaCl
Answer: B. 0.9% Normal saline
Rationale: Normal saline restores circulating volume in hypovolemia.
Q18. Chvostek’s sign is positive in which electrolyte disorder?
A. Hypocalcemia
B. Hypernatremia
C. Hypokalemia
D. Hypermagnesemia
Answer: A. Hypocalcemia
Rationale: Facial muscle twitching indicates calcium deficiency affecting nerve excitability.
Q19. Which electrolyte is primarily responsible for neuromuscular excitability?
A. Sodium
B. Potassium
C. Calcium
D. Magnesium
Answer: C. Calcium
Rationale: Calcium stabilizes cell membranes and controls muscle contractions.
Q20. Which intervention is appropriate for a patient with hypernatremia?
A. Restrict free water
B. Give isotonic saline
C. Provide hypotonic fluids
D. Increase salt intake
Answer: C. Provide hypotonic fluids
Rationale: Hypotonic fluids (e.g., 0.45% NaCl) lower serum sodium by diluting plasma.
Q21. Hypokalemia is most likely caused by:
A. Renal failure
B. Diarrhea or vomiting
C. Potassium-sparing diuretics
D. Addison’s disease
Answer: B. Diarrhea or vomiting
Rationale: GI losses deplete potassium stores.
Q22. Which electrolyte imbalance causes flattened T waves on ECG?
A. Hyperkalemia
B. Hypokalemia
C. Hypernatremia
D. Hypocalcemia
Answer: B. Hypokalemia
Rationale: Low potassium delays repolarization, producing flattened T waves.
Q23. A nurse should hold digoxin if the patient has:
A. Hyperkalemia
B. Hypokalemia
C. Hypernatremia
D. Hyponatremia
Answer: B. Hypokalemia
Rationale: Low potassium increases digoxin toxicity risk.
Q24. Which assessment finding indicates effective fluid replacement?
A. Decreased urine output
B. Normal skin turgor
C. Rapid weight loss
D. Increased thirst
Answer: B. Normal skin turgor
Rationale: Improved hydration restores normal turgor.
Q25. Which electrolyte imbalance is common in alcoholism?
A. Hypomagnesemia
B. Hypernatremia
C. Hyperkalemia
D. Hypercalcemia
Answer: A. Hypomagnesemia
Rationale: Alcohol increases magnesium excretion and decreases intake.
💡 Want to strengthen your basics before moving to advanced fluid therapy questions? Check out our NCLEX Fundamentals of Nursing Practice Questions — perfect for beginners.
💧 NCLEX Fluid and Electrolytes Practice Questions (26–50)
Q26. The nurse is reviewing lab results: Na⁺ 138 mEq/L, K⁺ 5.8 mEq/L, Ca²⁺ 9.0 mg/dL. Which value is abnormal?
A. Sodium
B. Potassium
C. Calcium
D. All are normal
Answer: B. Potassium
Rationale: Normal potassium levels are 3.5–5.0 mEq/L. A value of 5.8 indicates hyperkalemia, which may cause cardiac dysrhythmias.
Q27. A patient receiving IV potassium complains of burning at the site. The nurse should:
A. Stop the infusion immediately
B. Increase the rate
C. Check IV patency and dilute solution further
D. Add lidocaine to the IV bag
Answer: C. Check IV patency and dilute solution further
Rationale: Potassium is irritating to veins; it should always be diluted and administered slowly.
Q28. Which fluid should be given to a patient with hyponatremia due to excessive sweating?
A. 3% hypertonic saline
B. D5W
C. 0.9% normal saline
D. 0.45% NaCl
Answer: C. 0.9% normal saline
Rationale: Isotonic saline helps gradually restore sodium levels without causing cerebral edema.
Q29. Which electrolyte imbalance is associated with adrenal insufficiency (Addison’s disease)?
A. Hyponatremia and hyperkalemia
B. Hypernatremia and hypokalemia
C. Hypercalcemia
D. Hypomagnesemia
Answer: A. Hyponatremia and hyperkalemia
Rationale: Lack of aldosterone causes sodium loss and potassium retention.
Q30. A nurse caring for a patient with hypocalcemia should have which emergency equipment ready?
A. Suction
B. Tracheostomy set
C. Calcium gluconate
D. Defibrillator
Answer: C. Calcium gluconate
Rationale: IV calcium gluconate treats acute hypocalcemia and prevents laryngeal spasms.
Q31. Which finding suggests hypomagnesemia?
A. Hypoactive reflexes
B. Tremors and muscle twitching
C. Lethargy
D. Constipation
Answer: B. Tremors and muscle twitching
Rationale: Magnesium stabilizes neuromuscular activity; low levels increase excitability.
Q32. Which electrolyte imbalance causes prolonged QT interval on ECG?
A. Hypocalcemia
B. Hyperkalemia
C. Hypernatremia
D. Hypomagnesemia
Answer: A. Hypocalcemia
Rationale: Low calcium levels delay ventricular repolarization, prolonging QT interval.
Q33. The nurse notes swollen hands, crackles, and bounding pulses. Which condition is suspected?
A. Fluid deficit
B. Fluid overload
C. Dehydration
D. Shock
Answer: B. Fluid overload
Rationale: Excess fluid increases intravascular volume and hydrostatic pressure.
Q34. A patient receiving 3% NaCl develops headache and confusion. The nurse suspects:
A. Cerebral edema
B. Hypovolemia
C. Fluid overload and hypernatremia
D. Hypoglycemia
Answer: C. Fluid overload and hypernatremia
Rationale: Hypertonic saline pulls fluid into the vascular space, possibly causing brain dehydration.
Q35. Which electrolyte assists in transmission of nerve impulses and muscle contraction?
A. Sodium
B. Phosphate
C. Chloride
D. Bicarbonate
Answer: A. Sodium
Rationale: Sodium maintains osmotic balance and supports neuromuscular activity.
Q36. A patient’s potassium level is 2.9 mEq/L. Which symptom requires immediate action?
A. Muscle cramps
B. Diarrhea
C. Irregular heart rate
D. Increased urine output
Answer: C. Irregular heart rate
Rationale: Severe hypokalemia can cause life-threatening cardiac arrhythmias.
Q37. Which electrolyte imbalance occurs with prolonged NG suctioning?
A. Hyperkalemia
B. Hyponatremia
C. Hypokalemia and metabolic alkalosis
D. Hypercalcemia
Answer: C. Hypokalemia and metabolic alkalosis
Rationale: Gastric losses remove hydrogen and potassium ions.
Q38. A nurse should monitor which lab value in a patient on digoxin therapy?
A. Potassium
B. Calcium
C. Magnesium
D. Phosphate
Answer: A. Potassium
Rationale: Hypokalemia enhances digoxin’s toxic effects on cardiac tissue.
Q39. Which assessment finding suggests hypermagnesemia?
A. Deep tendon reflexes 4+
B. Tremors
C. Hypotension and bradycardia
D. Muscle twitching
Answer: C. Hypotension and bradycardia
Rationale: Excess magnesium depresses the CNS and slows cardiac conduction.
Q40. Which of the following best describes isotonic solutions?
A. Expand extracellular fluid without shifting water
B. Draw water from cells into vessels
C. Move water into cells
D. Decrease plasma volume
Answer: A. Expand extracellular fluid without shifting water
Rationale: Isotonic fluids maintain fluid balance between intracellular and extracellular compartments.
Q41. A patient with cirrhosis has ascites. The nurse expects which fluid shift?
A. Intracellular to intravascular
B. Intravascular to interstitial
C. Interstitial to intracellular
D. Intracellular to interstitial
Answer: B. Intravascular to interstitial
Rationale: Low albumin in liver disease reduces oncotic pressure, causing fluid leakage.
Q42. Which condition increases the risk of hyponatremia?
A. SIADH
B. Diabetes insipidus
C. Hyperventilation
D. Diarrhea
Answer: A. SIADH
Rationale: Excess antidiuretic hormone retains water, diluting serum sodium.
Q43. Which lab finding is most concerning in a patient on IV fluids?
A. Na⁺ 140 mEq/L
B. K⁺ 3.1 mEq/L
C. Ca²⁺ 9.5 mg/dL
D. Cl⁻ 101 mEq/L
Answer: B. K⁺ 3.1 mEq/L
Rationale: Hypokalemia (<3.5 mEq/L) can cause cardiac instability.
Q44. Which electrolyte imbalance often accompanies hypokalemia?
A. Hypomagnesemia
B. Hypernatremia
C. Hypercalcemia
D. Hyperphosphatemia
Answer: A. Hypomagnesemia
Rationale: Magnesium is needed for potassium reabsorption; low magnesium causes persistent hypokalemia.
Q45. A patient with DKA has serum potassium of 6.0 mEq/L. After insulin therapy begins, potassium level may:
A. Increase
B. Decrease
C. Remain the same
D. Fluctuate randomly
Answer: B. Decrease
Rationale: Insulin drives potassium into cells, reducing serum potassium.
Q46. Which fluid is contraindicated in a patient with increased intracranial pressure?
A. D5W
B. 3% NaCl
C. 0.9% NaCl
D. Lactated Ringer’s
Answer: A. D5W
Rationale: D5W becomes hypotonic and may worsen cerebral edema.
Q47. The nurse identifies which combination as dangerous for cardiac patients?
A. Digoxin and hypokalemia
B. Furosemide and hyperkalemia
C. Spironolactone and hyponatremia
D. Insulin and hypercalcemia
Answer: A. Digoxin and hypokalemia
Rationale: Low potassium increases digoxin binding to cardiac tissue, risking toxicity.
Q48. Which finding requires immediate intervention in a patient receiving diuretics?
A. Urine output 1500 mL/day
B. Potassium 3.0 mEq/L
C. Weight loss 1 lb/day
D. Blood pressure 120/80
Answer: B. Potassium 3.0 mEq/L
Rationale: Hypokalemia can cause arrhythmias; diuretic therapy should be re-evaluated.
Q49. Which condition results from overuse of antacids containing calcium?
A. Hypocalcemia
B. Hypercalcemia
C. Hypokalemia
D. Hypernatremia
Answer: B. Hypercalcemia
Rationale: Excessive calcium carbonate intake raises serum calcium.
Q50. Which symptom suggests hypernatremia?
A. Lethargy and confusion
B. Hypotension
C. Bradycardia
D. Excessive sweating
Answer: A. Lethargy and confusion
Rationale: Cellular dehydration from high sodium levels impairs cerebral function.
🔹 Related Topic: Review NCLEX Pathology MCQs to better understand how kidney function affects electrolytes and acid-base balance.*
⚗️ NCLEX Fluid & Electrolytes Practice Questions (51–75)
Q51. A patient’s potassium level is 6.2 mEq/L. Which intervention should the nurse anticipate?
A. Administer potassium supplements
B. Give insulin with glucose
C. Provide lactated Ringer’s
D. Restrict sodium intake
Answer: B. Give insulin with glucose
Rationale: Insulin drives potassium into cells, temporarily lowering serum potassium in hyperkalemia.
Q52. Which of the following best indicates effective rehydration?
A. Dark urine output
B. Flat neck veins
C. Stable blood pressure and moist mucous membranes
D. Increased thirst
Answer: C. Stable blood pressure and moist mucous membranes
Rationale: These findings confirm adequate intravascular volume restoration.
Q53. The nurse expects which acid–base disorder in a patient with prolonged diarrhea?
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis
Answer: A. Metabolic acidosis
Rationale: Bicarbonate loss from intestinal fluids leads to acidosis.
Q54. Which electrolyte imbalance causes positive Trousseau’s and Chvostek’s signs?
A. Hypokalemia
B. Hypocalcemia
C. Hypernatremia
D. Hypermagnesemia
Answer: B. Hypocalcemia
Rationale: Low calcium heightens neuromuscular excitability producing these classic signs.
Q55. A nurse is educating a patient about preventing dehydration. Which statement shows understanding?
A. “I will drink fluids only when thirsty.”
B. “I should drink water throughout the day, not just with meals.”
C. “I will limit fluids to prevent bloating.”
D. “Juice and soda are better than water.”
Answer: B.
Rationale: Regular water intake prevents fluid deficit and supports kidney function.
Q56. Which electrolyte imbalance is common in patients with bulimia?
A. Hypernatremia
B. Hypokalemia
C. Hyperkalemia
D. Hypercalcemia
Answer: B. Hypokalemia
Rationale: Vomiting causes potassium loss leading to muscle weakness and arrhythmias.
Q57. Which condition is likely in a patient with serum sodium of 118 mEq/L and confusion?
A. Hypernatremia
B. Hyponatremia
C. Hypokalemia
D. Hypercalcemia
Answer: B. Hyponatremia
Rationale: Low sodium causes cerebral edema leading to neurological symptoms.
Q58. Which fluid is safest for a patient with dehydration and diabetes insipidus?
A. D5W
B. 0.9% NaCl
C. 0.45% NaCl
D. 3% NaCl
Answer: A. D5W
Rationale: D5W becomes hypotonic in the body and helps replace free water losses.
Q59. The nurse observes a patient’s ECG showing peaked T waves. Which electrolyte imbalance is suspected?
A. Hypokalemia
B. Hyperkalemia
C. Hypocalcemia
D. Hypermagnesemia
Answer: B. Hyperkalemia
Rationale: High potassium accelerates repolarization, producing tall T waves.
Q60. Which symptom is specific to hypophosphatemia?
A. Bone pain and muscle weakness
B. Tetany
C. Confusion and seizures
D. Hypertension
Answer: A. Bone pain and muscle weakness
Rationale: Phosphate deficiency impairs energy metabolism and bone strength.
Q61. The nurse should closely monitor serum sodium in a patient taking which medication?
A. Furosemide
B. Ibuprofen
C. Aspirin
D. Lisinopril
Answer: A. Furosemide
Rationale: Loop diuretics increase sodium and water excretion, risking hyponatremia.
Q62. Which electrolyte imbalance causes decreased deep tendon reflexes?
A. Hypermagnesemia
B. Hypomagnesemia
C. Hypocalcemia
D. Hyponatremia
Answer: A. Hypermagnesemia
Rationale: Excess magnesium depresses the central nervous system.
Q63. Which lab finding supports fluid volume deficit?
A. Low hematocrit
B. Low BUN
C. Elevated specific gravity
D. Low serum sodium
Answer: C. Elevated specific gravity
Rationale: Concentrated urine indicates dehydration.
Q64. The nurse evaluates a patient on IV potassium. Which finding shows it’s effective?
A. Muscle cramps persist
B. Cardiac rhythm stabilizes
C. ECG shows flattened T waves
D. Weak pulse continues
Answer: B. Cardiac rhythm stabilizes
Rationale: Potassium normalization restores electrical activity.
Q65. A patient with hypercalcemia may require which medication?
A. Loop diuretic
B. Thiazide diuretic
C. Potassium supplement
D. Sodium bicarbonate
Answer: A. Loop diuretic
Rationale: Loop diuretics promote calcium excretion through urine.
Q66. Which condition is common with prolonged bed rest?
A. Hypocalcemia
B. Hypercalcemia
C. Hypokalemia
D. Hyponatremia
Answer: B. Hypercalcemia
Rationale: Bone resorption during immobility releases calcium into the bloodstream.
Q67. A nurse caring for a patient with renal failure expects which electrolyte abnormality?
A. Hypokalemia
B. Hyperkalemia
C. Hyponatremia
D. Hypocalcemia
Answer: B. Hyperkalemia
Rationale: Kidneys cannot excrete potassium effectively, leading to accumulation.
Q68. Which sign is most significant in a patient with fluid overload?
A. Decreased urine output
B. Rapid weight gain
C. Dry mucous membranes
D. Poor skin turgor
Answer: B. Rapid weight gain
Rationale: 1 kg weight gain ≈ 1 L fluid retention.
Q69. What is the best dietary source of potassium?
A. Cheese
B. Bananas
C. Bread
D. Rice
Answer: B. Bananas
Rationale: Bananas are rich in potassium, supporting cardiac and muscle function.
Q70. Which electrolyte imbalance causes respiratory depression?
A. Hypocalcemia
B. Hypermagnesemia
C. Hyponatremia
D. Hyperkalemia
Answer: B. Hypermagnesemia
Rationale: Excess magnesium suppresses neuromuscular transmission, leading to shallow respirations.
Q71. A nurse notices confusion in an elderly patient taking thiazide diuretics. The nurse suspects:
A. Hyponatremia
B. Hypernatremia
C. Hypocalcemia
D. Hyperkalemia
Answer: A. Hyponatremia
Rationale: Thiazides promote sodium loss, causing confusion and weakness in older adults.
Q72. Which intervention is correct for a patient with hypomagnesemia?
A. Restrict fluids
B. Administer magnesium sulfate IV
C. Administer calcium gluconate
D. Encourage antacids
Answer: B. Administer magnesium sulfate IV
Rationale: IV magnesium corrects deficiency and prevents seizures.
Q73. The nurse evaluates the effectiveness of fluid therapy. Which result indicates success?
A. Blood pressure remains low
B. Urine output 50 mL/hr
C. Weight decreases rapidly
D. Mucous membranes dry
Answer: B. Urine output 50 mL/hr
Rationale: Adequate renal perfusion and fluid balance are restored.
Q74. Which electrolyte imbalance can occur from excessive laxative use?
A. Hypernatremia
B. Hypokalemia
C. Hyperkalemia
D. Hypercalcemia
Answer: B. Hypokalemia
Rationale: Diarrhea and fluid loss reduce potassium levels.
Q75. The nurse is teaching about hyperkalemia management. Which statement shows understanding?
A. “I should use salt substitutes.”
B. “I must avoid potassium-rich foods like oranges.”
C. “I will take potassium supplements daily.”
D. “I can drink electrolyte drinks freely.”
Answer: B. I must avoid potassium-rich foods like oranges.
Rationale: Dietary restriction is essential to control high serum potassium.
💧 Don’t miss our NCLEX Physiology MCQs — many electrolyte disorders are directly linked to pH changes tested in NCLEX.
⚗️ NCLEX Fluid & Electrolytes Practice Questions (76–100)
Q76. Which electrolyte imbalance increases the risk of digoxin toxicity?
A. Hypokalemia
B. Hyperkalemia
C. Hypernatremia
D. Hypercalcemia
Answer: A. Hypokalemia
Rationale: Low potassium enhances digoxin’s effect on cardiac tissue, leading to toxicity.
Q77. Which fluid should be given for a patient in hypovolemic shock?
A. 0.9% Normal Saline
B. D5W
C. 0.45% NaCl
D. D10W
Answer: A. 0.9% Normal Saline
Rationale: Isotonic fluids restore intravascular volume effectively in hypovolemia.
Q78. What symptom is associated with hyperphosphatemia?
A. Tetany
B. Muscle weakness
C. Bone pain
D. Lethargy
Answer: A. Tetany
Rationale: Elevated phosphate lowers calcium levels, increasing neuromuscular irritability.
Q79. A patient with a history of chronic alcoholism may have which electrolyte imbalance?
A. Hypomagnesemia
B. Hypermagnesemia
C. Hyperkalemia
D. Hypercalcemia
Answer: A. Hypomagnesemia
Rationale: Poor nutrition and increased urinary loss in alcoholism cause magnesium deficiency.
Q80. Which intervention helps prevent hyponatremia in post-operative patients?
A. Encourage water only
B. Monitor IV fluids carefully
C. Restrict salt intake
D. Use hypotonic IV solutions
Answer: B. Monitor IV fluids carefully
Rationale: Overhydration with hypotonic fluids can dilute serum sodium levels.
Q81. A nurse identifies flat T waves and muscle weakness. Which lab finding supports this?
A. Potassium 2.9 mEq/L
B. Sodium 145 mEq/L
C. Calcium 10 mg/dL
D. Magnesium 2.0 mg/dL
Answer: A. Potassium 2.9 mEq/L
Rationale: Low potassium produces flattened T waves and muscle fatigue.
Q82. What is the most reliable indicator of overall fluid balance?
A. Blood pressure
B. Weight changes
C. Urine color
D. Skin turgor
Answer: B. Weight changes
Rationale: Daily weight reflects true body fluid gain or loss.
Q83. A patient receiving furosemide is at risk for which imbalance?
A. Hypokalemia
B. Hyperkalemia
C. Hypercalcemia
D. Hyponatremia
Answer: A. Hypokalemia
Rationale: Loop diuretics increase urinary potassium excretion.
Q84. Which electrolyte regulates neuromuscular function and blood clotting?
A. Calcium
B. Sodium
C. Potassium
D. Magnesium
Answer: A. Calcium
Rationale: Calcium is essential for nerve conduction and muscle contraction.
Q85. Which assessment finding indicates effective treatment of hypernatremia?
A. Increased thirst
B. Normal mental status and stable vitals
C. Dry mucous membranes
D. Elevated urine specific gravity
Answer: B. Normal mental status and stable vitals
Rationale: Correction of sodium imbalance restores hydration and brain function.
Q86. The nurse anticipates metabolic alkalosis in which condition?
A. Prolonged vomiting
B. Diarrhea
C. Diabetic ketoacidosis
D. Renal failure
Answer: A. Prolonged vomiting
Rationale: Loss of gastric acid causes excess bicarbonate, resulting in alkalosis.
Q87. Which electrolyte imbalance can cause cardiac arrest?
A. Hypokalemia
B. Hyperkalemia
C. Hypocalcemia
D. Hypomagnesemia
Answer: B. Hyperkalemia
Rationale: Severe hyperkalemia disrupts cardiac conduction, potentially leading to arrest.
Q88. Which lab finding indicates dehydration?
A. Low serum sodium
B. High hematocrit
C. Low urine specific gravity
D. Decreased BUN
Answer: B. High hematocrit
Rationale: Fluid loss concentrates red blood cells, raising hematocrit levels.
Q89. Which IV solution is hypotonic?
A. 0.45% NaCl
B. D5NS
C. D5LR
D. 3% NaCl
Answer: A. 0.45% NaCl
Rationale: Hypotonic fluids hydrate cells by moving water into intracellular spaces.
Q90. The nurse should report which symptom in a patient receiving IV potassium?
A. Burning at IV site
B. Increased thirst
C. Fatigue
D. Mild nausea
Answer: A. Burning at IV site
Rationale: Potassium is irritating to veins and must be infused slowly with monitoring.
Q91. Which patient is most at risk for hypernatremia?
A. A patient with excessive sweating
B. A patient receiving hypertonic saline
C. A patient with diarrhea
D. A patient on thiazide diuretics
Answer: B. A patient receiving hypertonic saline
Rationale: Sodium overload from hypertonic fluids raises serum sodium levels.
Q92. A nurse suspects metabolic acidosis when which lab result appears?
A. pH 7.30, HCO₃⁻ 18 mEq/L
B. pH 7.50, HCO₃⁻ 30 mEq/L
C. pH 7.40, CO₂ 40 mmHg
D. pH 7.45, HCO₃⁻ 26 mEq/L
Answer: A. pH 7.30, HCO₃⁻ 18 mEq/L
Rationale: Low pH and bicarbonate signify metabolic acidosis.
Q93. Which condition can cause hypocalcemia?
A. Hypoparathyroidism
B. Hyperparathyroidism
C. Dehydration
D. Adrenal insufficiency
Answer: A. Hypoparathyroidism
Rationale: Decreased parathyroid hormone reduces calcium release from bone.
Q94. Which symptom best reflects early fluid volume overload?
A. Crackles in lungs
B. Dry skin
C. Sunken eyes
D. Weight loss
Answer: A. Crackles in lungs
Rationale: Excess fluid accumulates in alveoli, producing crackles and shortness of breath.
Q95. Which electrolyte imbalance can develop from massive blood transfusion?
A. Hypocalcemia
B. Hyperkalemia
C. Hypercalcemia
D. Hyponatremia
Answer: A. Hypocalcemia
Rationale: Citrate in stored blood binds calcium, lowering serum levels.
Q96. The nurse should question which order for a patient with renal failure?
A. Kayexalate
B. Normal saline
C. Potassium chloride
D. Insulin with glucose
Answer: C. Potassium chloride
Rationale: Potassium supplements worsen hyperkalemia in renal failure.
Q97. Which of the following fluids is colloid?
A. Albumin
B. D5W
C. 0.9% NaCl
D. 0.45% NaCl
Answer: A. Albumin
Rationale: Colloids contain large molecules that stay in the vascular space to expand plasma volume.
Q98. The nurse observes twitching and positive Chvostek’s sign after thyroid surgery. What should she expect?
A. Hypocalcemia
B. Hypercalcemia
C. Hypokalemia
D. Hypermagnesemia
Answer: A. Hypocalcemia
Rationale: Accidental parathyroid removal leads to calcium deficiency.
Q99. Which statement is true regarding water balance in older adults?
A. They have higher total body water
B. Thirst sensation decreases with age
C. Kidneys excrete water more efficiently
D. Fluid requirements decrease
Answer: B. Thirst sensation decreases with age
Rationale: Older adults are prone to dehydration because they may not feel thirsty.
Q100. The nurse teaches that isotonic solutions are used to:
A. Expand extracellular fluid without altering cell size
B. Cause water to move into cells
C. Draw water out of cells
D. Replace intracellular fluid
Answer: A. Expand extracellular fluid without altering cell size
Rationale: Isotonic solutions have equal osmotic pressure as plasma, maintaining fluid balance.
🧠 Conclusion
Mastering fluid and electrolyte balance is vital for NCLEX success and safe nursing practice. Each question above tests your ability to analyze lab results, interpret clinical signs, and choose evidence-based interventions. Remember — these imbalances often appear subtly in NCLEX scenarios. Regularly practicing questions like these will strengthen your critical thinking and clinical reasoning.