HESI FLUID & ELECTROLYTES EXAM PREDICTION WITH
QUESTIONS AND CORRECT ANSWERS 2026 EDITION
,A patient with heart failure presents with 3+ pitting edema, crackles in
both lung fields, and a weight gain of 4 kg over 3 days. Which fluid
imbalance is most likely?
A. Hypovolemia
B. Isotonic dehydration
C. Hypervolemia
D. Third-spacing
Correct Answer: C
Explanation: Hypervolemia (fluid volume excess) is characterized by
weight gain, edema, and pulmonary crackles due to excess fluid in the
vascular space, commonly seen in heart failure. Hypovolemia presents
with weight loss and dry mucous membranes. Third-spacing involves
fluid shifting to interstitial spaces without necessarily causing systemic
hypervolemia signs initially.
Which electrolyte is the primary determinant of extracellular fluid (ECF)
osmolality?
A. Potassium
B. Calcium
C. Sodium
D. Magnesium
Correct Answer: C
Explanation: Sodium is the most abundant extracellular cation and the
primary determinant of ECF osmolality. Potassium is the primary
intracellular cation. Calcium and magnesium play roles in
neuromuscular function but do not primarily determine osmolality.
,A patient's serum sodium level is 128 mEq/L. Which symptom should
the nurse prioritize assessing?
A. Tetany
B. Confusion and lethargy
C. Muscle weakness
D. Tachycardia
Correct Answer: B
Explanation: Hyponatremia (Na+ <135 mEq/L) causes cerebral edema
leading to neurological symptoms like confusion, lethargy, and seizures.
Tetany is associated with hypocalcemia. Muscle weakness is more
typical of hypokalemia. Tachycardia is more common in hypovolemia or
hypernatremia.
Which acid-base imbalance is most likely in a patient with prolonged
vomiting?
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis
Correct Answer: B
Explanation: Prolonged vomiting causes loss of gastric hydrochloric acid
(HCl), leading to metabolic alkalosis. Metabolic acidosis occurs with
diarrhea or renal failure. Respiratory imbalances are related to CO2
retention or elimination.
A patient with chronic kidney disease has a serum potassium level of
6.8 mEq/L. Which ECG change should the nurse expect?
, A. Flat T waves
B. Peaked T waves
C. ST segment elevation
D. Prolonged PR interval
Correct Answer: B
Explanation: Hyperkalemia (K+ >5.0 mEq/L) causes peaked T waves on
ECG, followed by widened QRS and sine wave pattern in severe cases.
Flat T waves are seen in hypokalemia. ST elevation indicates myocardial
infarction.
Which fluid is classified as isotonic?
A. 0.45% NaCl
B. 0.9% NaCl
C. D5W
D. 3% NaCl
Correct Answer: B
Explanation: 0.9% NaCl (normal saline) is isotonic with plasma
(osmolality ~308 mOsm/L). 0.45% NaCl is hypotonic. D5W is isotonic in
the bag but becomes hypotonic once glucose is metabolized. 3% NaCl is
hypertonic.
A patient with severe diarrhea is at highest risk for which electrolyte
imbalance?
A. Hypernatremia
B. Hypokalemia
C. Hypercalcemia
D. Hypermagnesemia
QUESTIONS AND CORRECT ANSWERS 2026 EDITION
,A patient with heart failure presents with 3+ pitting edema, crackles in
both lung fields, and a weight gain of 4 kg over 3 days. Which fluid
imbalance is most likely?
A. Hypovolemia
B. Isotonic dehydration
C. Hypervolemia
D. Third-spacing
Correct Answer: C
Explanation: Hypervolemia (fluid volume excess) is characterized by
weight gain, edema, and pulmonary crackles due to excess fluid in the
vascular space, commonly seen in heart failure. Hypovolemia presents
with weight loss and dry mucous membranes. Third-spacing involves
fluid shifting to interstitial spaces without necessarily causing systemic
hypervolemia signs initially.
Which electrolyte is the primary determinant of extracellular fluid (ECF)
osmolality?
A. Potassium
B. Calcium
C. Sodium
D. Magnesium
Correct Answer: C
Explanation: Sodium is the most abundant extracellular cation and the
primary determinant of ECF osmolality. Potassium is the primary
intracellular cation. Calcium and magnesium play roles in
neuromuscular function but do not primarily determine osmolality.
,A patient's serum sodium level is 128 mEq/L. Which symptom should
the nurse prioritize assessing?
A. Tetany
B. Confusion and lethargy
C. Muscle weakness
D. Tachycardia
Correct Answer: B
Explanation: Hyponatremia (Na+ <135 mEq/L) causes cerebral edema
leading to neurological symptoms like confusion, lethargy, and seizures.
Tetany is associated with hypocalcemia. Muscle weakness is more
typical of hypokalemia. Tachycardia is more common in hypovolemia or
hypernatremia.
Which acid-base imbalance is most likely in a patient with prolonged
vomiting?
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis
Correct Answer: B
Explanation: Prolonged vomiting causes loss of gastric hydrochloric acid
(HCl), leading to metabolic alkalosis. Metabolic acidosis occurs with
diarrhea or renal failure. Respiratory imbalances are related to CO2
retention or elimination.
A patient with chronic kidney disease has a serum potassium level of
6.8 mEq/L. Which ECG change should the nurse expect?
, A. Flat T waves
B. Peaked T waves
C. ST segment elevation
D. Prolonged PR interval
Correct Answer: B
Explanation: Hyperkalemia (K+ >5.0 mEq/L) causes peaked T waves on
ECG, followed by widened QRS and sine wave pattern in severe cases.
Flat T waves are seen in hypokalemia. ST elevation indicates myocardial
infarction.
Which fluid is classified as isotonic?
A. 0.45% NaCl
B. 0.9% NaCl
C. D5W
D. 3% NaCl
Correct Answer: B
Explanation: 0.9% NaCl (normal saline) is isotonic with plasma
(osmolality ~308 mOsm/L). 0.45% NaCl is hypotonic. D5W is isotonic in
the bag but becomes hypotonic once glucose is metabolized. 3% NaCl is
hypertonic.
A patient with severe diarrhea is at highest risk for which electrolyte
imbalance?
A. Hypernatremia
B. Hypokalemia
C. Hypercalcemia
D. Hypermagnesemia
