KAPLAN NCLEX RN FLUID & ELECTROLYTE IMBALANCES
PREP EXAM 2026 Q&A
1. A patient with chronic kidney disease presents with a serum
potassium level of 6.8 mEq/L, peaked T waves on ECG, and
muscle weakness. Which intervention should the nurse
prioritize first?
A. Administer oral potassium chloride supplement
B. Administer IV calcium gluconate 10%
C. Encourage banana and orange intake
D. Monitor blood pressure every 4 hours
Correct Answer: B
Explanation: Calcium gluconate stabilizes the cardiac
membrane immediately in severe hyperkalemia, preventing
cardiac arrest. Potassium supplements (A) would worsen
the condition. Bananas and oranges (C) are high in
potassium and contraindicated. BP monitoring (D) is
important but not the priority over cardiac stabilization.
2. A 72-year-old patient with heart failure has been on
furosemide for 3 weeks and now presents with muscle
cramps, weakness, and a serum potassium of 2.9 mEq/L.
Which electrolyte imbalance is the nurse most concerned
about developing concurrently?
A. Hypernatremia
B. Hypomagnesemia
C. Hypercalcemia
D. Hypophosphatemia
Correct Answer: B
, Explanation: Loop diuretics like furosemide cause loss of
both potassium and magnesium. Hypomagnesemia often
accompanies hypokalemia and can make hypokalemia
refractory to treatment. Hypernatremia (A) is not typically
associated with furosemide use. Hypercalcemia (C) and
hypophosphatemia (D) are less common with this
medication.
3. A patient with severe dehydration from gastroenteritis has a
serum sodium of 158 mEq/L, dry mucous membranes, and
confusion. Which IV fluid is most appropriate for initial
replacement?
A. 0.9% NaCl (normal saline)
B. 0.45% NaCl (half-normal saline)
C. D5W (5% dextrose in water)
D. 3% NaCl (hypertonic saline)
Correct Answer: B
Explanation: The patient has hypernatremia (Na > 145
mEq/L) with dehydration. Half-normal saline (0.45%
NaCl) is hypotonic and will slowly correct the
hypernatremia while replacing volume. Normal saline (A)
is isotonic and won't correct hypernatremia. D5W (C)
becomes hypotonic but may cause rapid sodium drops.
Hypertonic saline (D) would worsen hypernatremia.
4. A patient with syndrome of inappropriate antidiuretic
hormone (SIADH) has a serum sodium of 118 mEq/L,
headache, and nausea. Which nursing intervention is most
appropriate?
, A. Administer 3% hypertonic saline缓慢
B. Encourage 3L fluid intake daily
C. Implement fluid restriction to 1L/day
D. Administer potassium-rich foods
Correct Answer: C
Explanation: SIADH causes water retention and dilutional
hyponatremia. Fluid restriction is the primary treatment to
prevent further sodium dilution. Hypertonic saline (A) may
be used in severe cases but isn't the first nursing
intervention. Increasing fluids (B) would worsen
hyponatremia. Potassium (D) doesn't address the sodium
problem.
5. A burned patient in the emergent phase (first 24 hours) is
most likely to develop which fluid/electrolyte imbalance?
A. Hypernatremia and hypovolemia
B. Hyponatremia and hyperkalemia
C. Hypocalcemia and hypomagnesemia
D. Hyperphosphatemia and hypokalemia
Correct Answer: B
Explanation: In the emergent phase of burns, massive fluid
shifts cause hypovolemia with sodium loss (hyponatremia)
and cellular breakdown releasing potassium
(hyperkalemia). Hypernatremia (A) occurs in the diuretic
phase. Hypocalcemia/hypomagnesemia (C) and
hyperphosphatemia/hypokalemia (D) are less
characteristic of the emergent burn phase.
, 6. A patient with Addison's disease presents with weakness,
weight loss, and a serum sodium of 128 mEq/L and
potassium of 5.8 mEq/L. Which medication is the nurse
expecting to administer?
A. Furosemide
B. Spironolactone
C. Hydrocortisone
D. Kayexalate
Correct Answer: C
Explanation: Addison's disease (primary adrenal
insufficiency) causes aldosterone deficiency, leading to
sodium loss (hyponatremia) and potassium retention
(hyperkalemia). Hydrocortisone replaces the deficient
cortisol and aldosterone. Furosemide (A) and
spironolactone (B) would worsen the imbalance.
Kayexalate (D) treats hyperkalemia but doesn't address the
underlying cause.
7. A patient receiving total parenteral nutrition (TPN) for 5
days develops tingling in fingers, muscle spasms, and a
serum calcium of 7.2 mg/dL. Which additional lab value is
most important to assess?
A. Serum magnesium
B. Serum sodium
C. Serum potassium
D. Serum chloride
Correct Answer: A
Explanation: Hypocalcemia with tetany symptoms requires
assessment of magnesium because hypomagnesemia can
cause or worsen hypocalcemia and make it refractory to
treatment. Sodium (B), potassium (C), and chloride (D) are
less directly related to calcium metabolism in this context.
PREP EXAM 2026 Q&A
1. A patient with chronic kidney disease presents with a serum
potassium level of 6.8 mEq/L, peaked T waves on ECG, and
muscle weakness. Which intervention should the nurse
prioritize first?
A. Administer oral potassium chloride supplement
B. Administer IV calcium gluconate 10%
C. Encourage banana and orange intake
D. Monitor blood pressure every 4 hours
Correct Answer: B
Explanation: Calcium gluconate stabilizes the cardiac
membrane immediately in severe hyperkalemia, preventing
cardiac arrest. Potassium supplements (A) would worsen
the condition. Bananas and oranges (C) are high in
potassium and contraindicated. BP monitoring (D) is
important but not the priority over cardiac stabilization.
2. A 72-year-old patient with heart failure has been on
furosemide for 3 weeks and now presents with muscle
cramps, weakness, and a serum potassium of 2.9 mEq/L.
Which electrolyte imbalance is the nurse most concerned
about developing concurrently?
A. Hypernatremia
B. Hypomagnesemia
C. Hypercalcemia
D. Hypophosphatemia
Correct Answer: B
, Explanation: Loop diuretics like furosemide cause loss of
both potassium and magnesium. Hypomagnesemia often
accompanies hypokalemia and can make hypokalemia
refractory to treatment. Hypernatremia (A) is not typically
associated with furosemide use. Hypercalcemia (C) and
hypophosphatemia (D) are less common with this
medication.
3. A patient with severe dehydration from gastroenteritis has a
serum sodium of 158 mEq/L, dry mucous membranes, and
confusion. Which IV fluid is most appropriate for initial
replacement?
A. 0.9% NaCl (normal saline)
B. 0.45% NaCl (half-normal saline)
C. D5W (5% dextrose in water)
D. 3% NaCl (hypertonic saline)
Correct Answer: B
Explanation: The patient has hypernatremia (Na > 145
mEq/L) with dehydration. Half-normal saline (0.45%
NaCl) is hypotonic and will slowly correct the
hypernatremia while replacing volume. Normal saline (A)
is isotonic and won't correct hypernatremia. D5W (C)
becomes hypotonic but may cause rapid sodium drops.
Hypertonic saline (D) would worsen hypernatremia.
4. A patient with syndrome of inappropriate antidiuretic
hormone (SIADH) has a serum sodium of 118 mEq/L,
headache, and nausea. Which nursing intervention is most
appropriate?
, A. Administer 3% hypertonic saline缓慢
B. Encourage 3L fluid intake daily
C. Implement fluid restriction to 1L/day
D. Administer potassium-rich foods
Correct Answer: C
Explanation: SIADH causes water retention and dilutional
hyponatremia. Fluid restriction is the primary treatment to
prevent further sodium dilution. Hypertonic saline (A) may
be used in severe cases but isn't the first nursing
intervention. Increasing fluids (B) would worsen
hyponatremia. Potassium (D) doesn't address the sodium
problem.
5. A burned patient in the emergent phase (first 24 hours) is
most likely to develop which fluid/electrolyte imbalance?
A. Hypernatremia and hypovolemia
B. Hyponatremia and hyperkalemia
C. Hypocalcemia and hypomagnesemia
D. Hyperphosphatemia and hypokalemia
Correct Answer: B
Explanation: In the emergent phase of burns, massive fluid
shifts cause hypovolemia with sodium loss (hyponatremia)
and cellular breakdown releasing potassium
(hyperkalemia). Hypernatremia (A) occurs in the diuretic
phase. Hypocalcemia/hypomagnesemia (C) and
hyperphosphatemia/hypokalemia (D) are less
characteristic of the emergent burn phase.
, 6. A patient with Addison's disease presents with weakness,
weight loss, and a serum sodium of 128 mEq/L and
potassium of 5.8 mEq/L. Which medication is the nurse
expecting to administer?
A. Furosemide
B. Spironolactone
C. Hydrocortisone
D. Kayexalate
Correct Answer: C
Explanation: Addison's disease (primary adrenal
insufficiency) causes aldosterone deficiency, leading to
sodium loss (hyponatremia) and potassium retention
(hyperkalemia). Hydrocortisone replaces the deficient
cortisol and aldosterone. Furosemide (A) and
spironolactone (B) would worsen the imbalance.
Kayexalate (D) treats hyperkalemia but doesn't address the
underlying cause.
7. A patient receiving total parenteral nutrition (TPN) for 5
days develops tingling in fingers, muscle spasms, and a
serum calcium of 7.2 mg/dL. Which additional lab value is
most important to assess?
A. Serum magnesium
B. Serum sodium
C. Serum potassium
D. Serum chloride
Correct Answer: A
Explanation: Hypocalcemia with tetany symptoms requires
assessment of magnesium because hypomagnesemia can
cause or worsen hypocalcemia and make it refractory to
treatment. Sodium (B), potassium (C), and chloride (D) are
less directly related to calcium metabolism in this context.
