FLUID AND ELECTROLYTE BALANCE QUESTIONS
AND ANSWERS | LATEST 2026/2027
1. A patient has a serum sodium level of 118 mEq/L. Which assessment finding is
most concerning?
A. Dry mucous membranes
B. Seizure activity
C. Muscle cramps
D. Thirst
Answer: B
*Rationale: Severe hyponatremia (<120 mEq/L) causes cerebral edema and
seizures. Seizure activity is a medical emergency requiring hypertonic saline. Dry
mucous membranes and thirst suggest hypernatremia.*
2. A patient with heart failure has a serum potassium of 2.9 mEq/L. Which
medication, if ordered, should the nurse question?
A. Furosemide 40 mg IV
B. Digoxin 0.125 mg PO
C. Spironolactone 25 mg PO
D. Lisinopril 10 mg PO
Answer: A
*Rationale: Hypokalemia (2.9) can be worsened by loop diuretics like furosemide.
Spironolactone is potassium-sparing and may be appropriate. Digoxin toxicity risk
increases with hypokalemia, but furosemide is the direct cause of potassium
loss.*
3. A patient’s arterial blood gas (ABG) shows: pH 7.25, PaCO2 55 mm Hg, HCO3
24 mEq/L. Which condition is most likely?
,A. Metabolic acidosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Respiratory alkalosis
Answer: B
Rationale: Low pH (acidemia) with elevated PaCO2 (hypercapnia) and normal
HCO3 indicates acute respiratory acidosis. Common causes include COPD
exacerbation, opioid overdose, or pneumonia.
4. Which IV fluid is isotonic and most appropriate for initial resuscitation in
hypovolemic shock?
A. 0.45% normal saline (half-normal)
B. 5% dextrose in water (D5W)
C. 0.9% normal saline
D. 3% normal saline
Answer: C
*Rationale: 0.9% normal saline is isotonic and expands intravascular volume. Half-
normal is hypotonic. D5W becomes hypotonic after dextrose metabolism. 3%
saline is hypertonic (for severe hyponatremia).*
5. A patient with chronic kidney disease has a serum phosphorus level of 7.2
mg/dL (normal 2.5–4.5). Which assessment finding is expected?
A. Muscle tetany
B. Prolonged QT interval
C. Hypocalcemia
D. Hyperreflexia
Answer: C
Rationale: Hyperphosphatemia binds with calcium, causing hypocalcemia. Tetany
and prolonged QT occur with hypocalcemia (but the question asks what is
expected from hyperphosphatemia—hypocalcemia is the direct effect).
,6. A patient is receiving IV furosemide. Which electrolyte imbalance should the
nurse monitor most closely?
A. Hyperkalemia
B. Hypokalemia
C. Hypernatremia
D. Hypermagnesemia
Answer: B
Rationale: Loop diuretics (furosemide) cause potassium wasting in the distal
tubule, leading to hypokalemia. Monitor for muscle weakness, arrhythmias, and
digoxin toxicity.
7. A patient has a serum calcium level of 12.5 mg/dL (normal 8.5–10.2). Which
symptom is most likely?
A. Chvostek’s sign
B. Trousseau’s sign
C. Muscle tetany
D. Constipation and lethargy
Answer: D
Rationale: Hypercalcemia causes “bones, stones, groans, psychiatric overtones”
(constipation, lethargy, polyuria, kidney stones). Chvostek’s, Trousseau’s, and
tetany are signs of hypocalcemia.
8. A patient with diabetic ketoacidosis has a serum potassium of 5.9 mEq/L
despite total body potassium depletion. Why does this occur?
A. Renal failure from dehydration
B. Acidosis shifts potassium extracellularly
C. Excessive potassium intake
D. Hemolysis of blood sample
, Answer: B
Rationale: In DKA, acidosis causes hydrogen ions to move into cells, pushing
potassium out (extracellular shift). Total body potassium is low, but serum level
may be normal or high until insulin therapy is started.
9. Which patient is at highest risk for developing hypermagnesemia?
A. Patient taking magnesium citrate laxatives daily
B. Patient with chronic diarrhea
C. Patient on a low-magnesium diet
D. Patient receiving loop diuretics
Answer: A
Rationale: Hypermagnesemia occurs with excessive magnesium intake (antacids,
laxatives) especially in renal impairment. Diarrhea, low intake, and diuretics cause
hypomagnesemia.
10. A patient’s ABG shows: pH 7.50, PaCO2 30 mm Hg, HCO3 24 mEq/L. Which
condition is most likely?
A. Metabolic alkalosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Respiratory acidosis
Answer: B
Rationale: High pH (alkalemia) with low PaCO2 (hypocapnia) and normal HCO3
indicates acute respiratory alkalosis. Causes include anxiety, pulmonary embolism,
or mechanical overventilation.
11. A patient with SIADH (syndrome of inappropriate antidiuretic hormone) has
a serum sodium of 124 mEq/L. Which fluid order is most appropriate?
A. 0.9% normal saline at 150 mL/hr
AND ANSWERS | LATEST 2026/2027
1. A patient has a serum sodium level of 118 mEq/L. Which assessment finding is
most concerning?
A. Dry mucous membranes
B. Seizure activity
C. Muscle cramps
D. Thirst
Answer: B
*Rationale: Severe hyponatremia (<120 mEq/L) causes cerebral edema and
seizures. Seizure activity is a medical emergency requiring hypertonic saline. Dry
mucous membranes and thirst suggest hypernatremia.*
2. A patient with heart failure has a serum potassium of 2.9 mEq/L. Which
medication, if ordered, should the nurse question?
A. Furosemide 40 mg IV
B. Digoxin 0.125 mg PO
C. Spironolactone 25 mg PO
D. Lisinopril 10 mg PO
Answer: A
*Rationale: Hypokalemia (2.9) can be worsened by loop diuretics like furosemide.
Spironolactone is potassium-sparing and may be appropriate. Digoxin toxicity risk
increases with hypokalemia, but furosemide is the direct cause of potassium
loss.*
3. A patient’s arterial blood gas (ABG) shows: pH 7.25, PaCO2 55 mm Hg, HCO3
24 mEq/L. Which condition is most likely?
,A. Metabolic acidosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Respiratory alkalosis
Answer: B
Rationale: Low pH (acidemia) with elevated PaCO2 (hypercapnia) and normal
HCO3 indicates acute respiratory acidosis. Common causes include COPD
exacerbation, opioid overdose, or pneumonia.
4. Which IV fluid is isotonic and most appropriate for initial resuscitation in
hypovolemic shock?
A. 0.45% normal saline (half-normal)
B. 5% dextrose in water (D5W)
C. 0.9% normal saline
D. 3% normal saline
Answer: C
*Rationale: 0.9% normal saline is isotonic and expands intravascular volume. Half-
normal is hypotonic. D5W becomes hypotonic after dextrose metabolism. 3%
saline is hypertonic (for severe hyponatremia).*
5. A patient with chronic kidney disease has a serum phosphorus level of 7.2
mg/dL (normal 2.5–4.5). Which assessment finding is expected?
A. Muscle tetany
B. Prolonged QT interval
C. Hypocalcemia
D. Hyperreflexia
Answer: C
Rationale: Hyperphosphatemia binds with calcium, causing hypocalcemia. Tetany
and prolonged QT occur with hypocalcemia (but the question asks what is
expected from hyperphosphatemia—hypocalcemia is the direct effect).
,6. A patient is receiving IV furosemide. Which electrolyte imbalance should the
nurse monitor most closely?
A. Hyperkalemia
B. Hypokalemia
C. Hypernatremia
D. Hypermagnesemia
Answer: B
Rationale: Loop diuretics (furosemide) cause potassium wasting in the distal
tubule, leading to hypokalemia. Monitor for muscle weakness, arrhythmias, and
digoxin toxicity.
7. A patient has a serum calcium level of 12.5 mg/dL (normal 8.5–10.2). Which
symptom is most likely?
A. Chvostek’s sign
B. Trousseau’s sign
C. Muscle tetany
D. Constipation and lethargy
Answer: D
Rationale: Hypercalcemia causes “bones, stones, groans, psychiatric overtones”
(constipation, lethargy, polyuria, kidney stones). Chvostek’s, Trousseau’s, and
tetany are signs of hypocalcemia.
8. A patient with diabetic ketoacidosis has a serum potassium of 5.9 mEq/L
despite total body potassium depletion. Why does this occur?
A. Renal failure from dehydration
B. Acidosis shifts potassium extracellularly
C. Excessive potassium intake
D. Hemolysis of blood sample
, Answer: B
Rationale: In DKA, acidosis causes hydrogen ions to move into cells, pushing
potassium out (extracellular shift). Total body potassium is low, but serum level
may be normal or high until insulin therapy is started.
9. Which patient is at highest risk for developing hypermagnesemia?
A. Patient taking magnesium citrate laxatives daily
B. Patient with chronic diarrhea
C. Patient on a low-magnesium diet
D. Patient receiving loop diuretics
Answer: A
Rationale: Hypermagnesemia occurs with excessive magnesium intake (antacids,
laxatives) especially in renal impairment. Diarrhea, low intake, and diuretics cause
hypomagnesemia.
10. A patient’s ABG shows: pH 7.50, PaCO2 30 mm Hg, HCO3 24 mEq/L. Which
condition is most likely?
A. Metabolic alkalosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Respiratory acidosis
Answer: B
Rationale: High pH (alkalemia) with low PaCO2 (hypocapnia) and normal HCO3
indicates acute respiratory alkalosis. Causes include anxiety, pulmonary embolism,
or mechanical overventilation.
11. A patient with SIADH (syndrome of inappropriate antidiuretic hormone) has
a serum sodium of 124 mEq/L. Which fluid order is most appropriate?
A. 0.9% normal saline at 150 mL/hr
