HESI FUNDAMENTALS 2026
COMPREHENSIVE EXAM PREP HIGH
YIELD QUESTIONS
HESI Fundamentals: Fluid, Electrolytes & Acid-Base
Practice
Question 1
A nurse is assessing a client who has a serum sodium level of 118
mEq/L. Which of the following clinical findings should the nurse
prioritize as the most critical risk for this client?
A. Generalized muscle weakness
B. Altered mental status and generalized seizures
C. Dry mucous membranes and intense thirst
D. Decreased deep tendon reflexes
CorreCt Answer: B. Altered mental status and
generalized seizures
rAtionAle: A serum sodium level below 120 mEq/L
indicates severe hyponatremia. Low extracellular
sodium causes osmotic fluid shifts, forcing water into
brain cells and causing cerebral edema. This leads
rapidly to neurological deterioration, altered level of
consciousness, seizures, coma, and brain herniation.
Muscle weakness and hyporeflexia can occur but are
lower priority than neurological collapse.
Question 2
,The nurse is reviewing a client's arterial blood gas (ABG) results:
pH 7.31, PaCO2 38 mm Hg, HCO3 16 mEq/L. How should
the nurse interpret these findings?
A. Uncompensated respiratory acidosis
B. Partially compensated metabolic alkalosis
C. Uncompensated metabolic acidosis
D. Fully compensated respiratory alkalosis
CorreCt Answer: C. Uncompensated metabolic acidosis
rAtionAle: The pH is low (< 7.35), demonstrating
acidosis. The bicarbonate (HCO3) is also low (< 22
mEq/L), which matches the acidotic state and points to a
metabolic origin. Because the PaCO2 is within its normal
range (35–45 mm Hg), the respiratory system has not
yet begun compensating for the metabolic imbalance,
making it uncompensated.
Question 3
A client is admitted to the unit with a serum potassium level of
6.2 mEq/L. Which immediate intervention should the nurse
anticipate implementing first?
A. Administering an oral potassium-wasting diuretic.
B. Obtaining a 12-lead electrocardiogram (ECG).
C. Infusing a 0.9% normal saline fluid bolus.
D. Encouraging increased intake of dietary fiber.
CorreCt Answer: B. Obtaining a 12-lead
electrocardiogram (ECG).
,rAtionAle: Severe hyperkalemia (> 5.0 mEq/L)
directly alters the electrical conduction system of the
heart, putting the client at high risk for lethal cardiac
dysrhythmias, such as ventricular fibrillation or
asystole. Assessing the heart's electrical stability via an
ECG is the absolute first action to check for tall, peaked T
waves, a widened QRS, or a prolonged PR interval.
Question 4
A nurse is evaluating an older adult client with severe fluid
volume deficit. Which assessment finding provides the most
reliable indicator of a changing fluid status in this specific
population?
A. Skin turgor tested over the back of the hand.
B. Daily weights obtained at the same time every morning.
C. Presence of 1+ pitting ankle edema.
D. Reports of extreme thirst and a dry mouth.
CorreCt Answer: B. Daily weights obtained at the same
time every morning.
rAtionAle: Daily body weight is the most sensitive
and reproducible tool to assess fluid volume gains or
losses in all adult clients. Skin turgor is unreliable in
older adults due to a natural loss of skin elasticity. Thirst
mechanisms also diminish significantly with age,
making subjective reports an inaccurate gauge of
systemic hydration.
, Question 5
The nurse is caring for a client with a history of chronic
alcoholism who presents with a serum magnesium level of 1.1
mEq/L. Which corresponding electrolyte imbalance should the
nurse closely monitor for due to its relationship with magnesium
regulation?
A. Hypernatremia
B. Hypocalcemia
C. Hyperphosphatemia
D. Hypochromia
CorreCt Answer: B. Hypocalcemia
rAtionAle: Hypomagnesemia (< 1.3 mEq/L) impairs
the secretion and action of parathyroid hormone (PTH).
Because PTH is responsible for maintaining normal
blood calcium levels, a severe magnesium deficiency
secondary to malnutrition or chronic alcoholism
frequently precipitates hypocalcemia, causing
neuromuscular irritability and positive
Chvostek's/Trousseau's signs.
Question 6
The nurse is caring for a client who has a serum calcium level of
6.4 mg/dL. Which physical assessment finding should the nurse
expect to elicit?
A. Constipation and hypoactive bowel sounds.
B. Carpopedal spasm during blood pressure cuff inflation.
COMPREHENSIVE EXAM PREP HIGH
YIELD QUESTIONS
HESI Fundamentals: Fluid, Electrolytes & Acid-Base
Practice
Question 1
A nurse is assessing a client who has a serum sodium level of 118
mEq/L. Which of the following clinical findings should the nurse
prioritize as the most critical risk for this client?
A. Generalized muscle weakness
B. Altered mental status and generalized seizures
C. Dry mucous membranes and intense thirst
D. Decreased deep tendon reflexes
CorreCt Answer: B. Altered mental status and
generalized seizures
rAtionAle: A serum sodium level below 120 mEq/L
indicates severe hyponatremia. Low extracellular
sodium causes osmotic fluid shifts, forcing water into
brain cells and causing cerebral edema. This leads
rapidly to neurological deterioration, altered level of
consciousness, seizures, coma, and brain herniation.
Muscle weakness and hyporeflexia can occur but are
lower priority than neurological collapse.
Question 2
,The nurse is reviewing a client's arterial blood gas (ABG) results:
pH 7.31, PaCO2 38 mm Hg, HCO3 16 mEq/L. How should
the nurse interpret these findings?
A. Uncompensated respiratory acidosis
B. Partially compensated metabolic alkalosis
C. Uncompensated metabolic acidosis
D. Fully compensated respiratory alkalosis
CorreCt Answer: C. Uncompensated metabolic acidosis
rAtionAle: The pH is low (< 7.35), demonstrating
acidosis. The bicarbonate (HCO3) is also low (< 22
mEq/L), which matches the acidotic state and points to a
metabolic origin. Because the PaCO2 is within its normal
range (35–45 mm Hg), the respiratory system has not
yet begun compensating for the metabolic imbalance,
making it uncompensated.
Question 3
A client is admitted to the unit with a serum potassium level of
6.2 mEq/L. Which immediate intervention should the nurse
anticipate implementing first?
A. Administering an oral potassium-wasting diuretic.
B. Obtaining a 12-lead electrocardiogram (ECG).
C. Infusing a 0.9% normal saline fluid bolus.
D. Encouraging increased intake of dietary fiber.
CorreCt Answer: B. Obtaining a 12-lead
electrocardiogram (ECG).
,rAtionAle: Severe hyperkalemia (> 5.0 mEq/L)
directly alters the electrical conduction system of the
heart, putting the client at high risk for lethal cardiac
dysrhythmias, such as ventricular fibrillation or
asystole. Assessing the heart's electrical stability via an
ECG is the absolute first action to check for tall, peaked T
waves, a widened QRS, or a prolonged PR interval.
Question 4
A nurse is evaluating an older adult client with severe fluid
volume deficit. Which assessment finding provides the most
reliable indicator of a changing fluid status in this specific
population?
A. Skin turgor tested over the back of the hand.
B. Daily weights obtained at the same time every morning.
C. Presence of 1+ pitting ankle edema.
D. Reports of extreme thirst and a dry mouth.
CorreCt Answer: B. Daily weights obtained at the same
time every morning.
rAtionAle: Daily body weight is the most sensitive
and reproducible tool to assess fluid volume gains or
losses in all adult clients. Skin turgor is unreliable in
older adults due to a natural loss of skin elasticity. Thirst
mechanisms also diminish significantly with age,
making subjective reports an inaccurate gauge of
systemic hydration.
, Question 5
The nurse is caring for a client with a history of chronic
alcoholism who presents with a serum magnesium level of 1.1
mEq/L. Which corresponding electrolyte imbalance should the
nurse closely monitor for due to its relationship with magnesium
regulation?
A. Hypernatremia
B. Hypocalcemia
C. Hyperphosphatemia
D. Hypochromia
CorreCt Answer: B. Hypocalcemia
rAtionAle: Hypomagnesemia (< 1.3 mEq/L) impairs
the secretion and action of parathyroid hormone (PTH).
Because PTH is responsible for maintaining normal
blood calcium levels, a severe magnesium deficiency
secondary to malnutrition or chronic alcoholism
frequently precipitates hypocalcemia, causing
neuromuscular irritability and positive
Chvostek's/Trousseau's signs.
Question 6
The nurse is caring for a client who has a serum calcium level of
6.4 mg/dL. Which physical assessment finding should the nurse
expect to elicit?
A. Constipation and hypoactive bowel sounds.
B. Carpopedal spasm during blood pressure cuff inflation.
