Pediatric Fluid and Electrolyte Imbalances Practice Questions
23 free Pediatric Fluid and Electrolyte Imbalances practice questions for the NCLEX Exam. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
A 4-year-old child receiving maintenance IV fluids is ordered 0.45% sodium chloride at full maintenance rate. The nurse recognises a risk when the child’s serum sodium is 130 mEq/L because:
- A Hypotonic fluid may worsen hyponatremia and risk cerebral edema
- B Hypotonic fluid is preferred to restore sodium quickly
- C Serum sodium has little bearing on IV fluid selection
- D The ordered rate is appropriate as long as sodium is low
Correct answer: Hypotonic fluid may worsen hyponatremia and risk cerebral edema
Hypotonic fluids in the setting of low sodium may lower serum sodium further, risking cerebral edema; children must have appropriate tonicity.
Which key nursing assessment is especially important in young children because of their higher insensible fluid losses through skin and lungs?
- A Passive range-of-motion exercises
- B Daily weight and skin turgor
- C Serial head circumference measurement
- D Routine hearing acuity screening
Correct answer: Daily weight and skin turgor
Infants and young children have greater insensible fluid losses, so assessing skin turgor, daily weight and fluid balance is crucial.
In managing a child with hypernatremic dehydration, the nurse knows that the serum sodium must be corrected:
- A Very rapidly to normal within 2 hours
- B At a slow rate to avoid cerebral edema
- C Only with hypotonic fluid bolus
- D Without monitoring levels
Correct answer: At a slow rate to avoid cerebral edema
Rapid correction of hypernatremia can cause cerebral edema because of fluid shifts into cells; gradual correction is safer.
A toddler presents with weight loss equal to 5% of body weight, delayed capillary refill, and urine output less than normal. According to pediatric dehydration criteria, this corresponds to:
- A Severe dehydration
- B Mild dehydration
- C No dehydration
- D Moderate dehydration requiring IV fluids
Correct answer: Mild dehydration
In children weight loss of ~4-6% corresponds to moderate; ~3-4% might be mild; 5% in a toddler is mild-moderate rather than severe.
During fluid therapy for a dehydrated child, monitoring which of the following is most useful to assess ongoing fluid balance?
- A Daily height measurement
- B Intake/output, daily weight, and urine specific gravity
- C Blood pressure readings alone
- D Respiratory rate trends alone
Correct answer: Intake/output, daily weight, and urine specific gravity
Intake/output records, daily weights and urine specific gravity help evaluate fluid balance and changes in fluid status in children.
A child with hyperkalemia is most at risk for which major complication?
- A Hyporeflexia limited to the lower limbs
- B Cardiac arrhythmias and cardiac arrest
- C Mild constipation and abdominal cramping
- D Urethral obstruction with urinary retention
Correct answer: Cardiac arrhythmias and cardiac arrest
Elevated serum potassium affects cardiac conduction and can lead to dangerous arrhythmias and cardiac arrest.
Which finding is most consistent with severe dehydration in children?
- A Slightly increased pulse with normal capillary refill and moist lips
- B Weight loss of about 2% with moist mucous membranes and normal pulse
- C Weight loss > 10%, sunken fontanel, capillary refill > 4 seconds
- D Normal anterior fontanel with brisk capillary refill and good skin turgor
Correct answer: Weight loss > 10%, sunken fontanel, capillary refill > 4 seconds
In infants a > 10% weight loss plus signs such as sunken fontanel, delayed capillary refill indicate severe dehydration.
Why is the isotonic solution preferred over a hypotonic one for a child with vomiting and diarrhea?
- A Hypotonic solutions expand intravascular volume far more quickly than isotonic ones
- B Isotonic fluids avoid rapid water shifts into cells and restore circulation safely
- C Hypotonic solutions raise serum sodium faster, correcting any deficit sooner
- D Isotonic solutions carry essentially no risk of any electrolyte imbalance
Correct answer: Isotonic fluids avoid rapid water shifts into cells and restore circulation safely
Pediatric fluid therapy guidelines indicate isotonic fluids for volume depletion because hypotonic fluids can lead to dangerous shifts (especially in sick children).
Which characteristic of infants makes them more vulnerable to fluid and electrolyte disturbances than older children?
- A A markedly lower total body water percentage than older children
- B A consistently slower basal metabolic rate than older children
- C Higher body surface area-to-weight ratio and higher TBW percent
- D Fully mature renal concentrating ability from early infancy
Correct answer: Higher body surface area-to-weight ratio and higher TBW percent
Infants have higher total body water (around 70-80% of body weight) and a larger surface area relative to weight, leading to greater insensible losses and fluid/electrolyte risk.
Using the Holliday-Segar formula, what is the approximate maintenance fluid requirement per day for a 10-kg child who has had vomiting and poor intake for two days?
- A 500 mL
- B 600 mL
- C 800 mL
- D 1000 mL
Correct answer: 1000 mL
The classic Holliday-Segar method uses 100 mL/kg for first 10 kg → 10 kg × 100 = 1000 mL/day.
Why is potassium replacement critical even before insulin therapy in a child with diabetic ketoacidosis (DKA)?
- A Insulin shifts potassium into cells, lowering serum K+ further
- B Insulin reliably raises the potassium level in the blood
- C Potassium replacement is essentially never indicated in DKA
- D Close monitoring of the child is not necessary during treatment
Correct answer: Insulin shifts potassium into cells, lowering serum K+ further
In DKA, even if serum K+ appears low, insulin therapy will drive potassium into cells, worsening hypokalemia unless replaced appropriately.
Which statement is correct regarding fluid correction for a 2-year-old child with hypernatremia (serum sodium 156 mEq/L)?
- A Rapid correction is safe and tends to shorten hospital stay
- B Correction should be slow (over ~48 hours) to prevent cerebral edema
- C Hypotonic fluids are always strictly contraindicated in this child
- D There is no need to monitor neurologic status during the correction
Correct answer: Correction should be slow (over ~48 hours) to prevent cerebral edema
In children, hypernatremia must be corrected gradually to avoid cerebral edema; pediatric guidelines caution against rapid lowering of sodium.
In a child with prolonged diarrhea, which electrolyte losses are most important to replace in this pediatric scenario?
- A Calcium losses only, with sodium kept in reserve
- B Sodium and chloride (and water)
- C Potassium losses only, with no fluid replacement
- D Magnesium losses only, replaced with supplements
Correct answer: Sodium and chloride (and water)
Vomiting/diarrhea cause losses of sodium and chloride (and water), so ORS aims to replace those plus water in children.
What is correct for moderate dehydration in a child in terms of percent weight loss?
- A Weight loss of < 3%
- B Weight loss of 4-6%
- C Weight loss of 8-10%
- D Weight loss of > 11%
Correct answer: Weight loss of 4-6%
For children moderate dehydration is about 4-6% weight loss; severe is >7% in children.
Which factor in infants may contribute to a falsely elevated potassium reading when suspecting pseudohyperkalemia?
- A A prolonged fasting state before the blood sample
- B Small-needle draw with tissue squeezing causing hemolysis
- C A completely normal glomerular filtration rate
- D A persistently high urinary output before sampling
Correct answer: Small-needle draw with tissue squeezing causing hemolysis
In children, particularly infants, hemolysis or tissue squeezing during small-needle draws can cause pseudohyperkalemia.
Why are insensible and wound fluid losses included when calculating fluid replacement for a child with severe burns?
- A Pediatric maintenance fluids already cover insensible and wound losses
- B Burn deficits can exceed maintenance and need extra replacement
- C Children require less fluid per kilogram than adults during burns
- D Isotonic fluids are essentially never indicated in pediatric burns
Correct answer: Burn deficits can exceed maintenance and need extra replacement
In pediatric burn patients, fluid loss may be substantial (wound + insensible) and standard maintenance isn’t enough; additional replacement is needed.
In a child with pyloric stenosis and resultant metabolic alkalosis, which electrolyte disturbance is most likely to be seen?
- A Hyperkalemia from cellular potassium shifts
- B Hypochloremia and hypokalemia
- C Isolated hypernatremia without other changes
- D Hypermagnesemia from renal retention
Correct answer: Hypochloremia and hypokalemia
Continuous vomiting causes loss of stomach acid and chloride → metabolic alkalosis; also potassium loss leading to hypokalemia and hypochloremia.
When assessing a child for dehydration, which physical sign needs cautious interpretation compared to adults?
- A Capillary refill
- B Anterior fontanel in infants
- C Skin turgor
- D Heart rate
Correct answer: Skin turgor
In infants and young children, skin turgor may be less reliable due to greater mobility of skin and subcutaneous fat; fontanel and other signs may be more telling.
Which electrolyte does the nurse particularly monitor in a child with congestive heart failure when loop diuretics are used?
- A Sodium level alone, as it falls fastest
- B Potassium and magnesium
- C Calcium level alone, as it drops first
- D Phosphate level alone, as it is most affected
Correct answer: Potassium and magnesium
Loop diuretics cause potassium and magnesium loss, increasing risk of electrolyte imbalance in pediatric patients with heart failure and fluid management.
Why is potassium replacement still likely needed even if a child with DKA has an initial potassium level of 5.8 mEq/L?
- A Because serum potassium stays high throughout treatment
- B Because insulin and fluids drive K+ into cells while urinary losses continue
- C Because only the sodium level is clinically relevant here
- D Because children are unable to excrete potassium effectively
Correct answer: Because insulin and fluids drive K+ into cells while urinary losses continue
Even if initial serum potassium is elevated in DKA, total body potassium is depleted and once insulin and fluid therapy start, potassium shifts intracellularly and urinary losses continue—requiring replacement.
Why is potassium replacement critical even before insulin therapy in a child with diabetic ketoacidosis (DKA)?
- A Cerebral edema and seizures
- B Rapid dehydration and weight loss
- C Sudden hypernatremia and thirst
- D Acute renal failure as the only risk
Correct answer: Cerebral edema and seizures
In DKA, even if serum K+ appears low, insulin therapy will drive potassium into cells, worsening hypokalemia unless replaced appropriately.
Which complication is a 6-month‐old infant at risk for if found to have hyponatremia after receiving excessive hypotonic IV fluids?
- A Cerebral edema and seizures
- B Rapid dehydration
- C Hypernatremia
- D Renal failure only
Correct answer: Cerebral edema and seizures
Hyponatremia from too rapid or excessive hypotonic fluid in infants can lead to cerebral edema and seizures due to fluid shift into brain cells.
What should be the rates of ORT for a child with moderate dehydration after gastroenteritis?
- A Same as maintenance fluid rates for healthy child
- B Slower than maintenance because of risk of overload
- C Faster than maintenance only if signs of shock
- D Irrelevant – give whatever child wants
Correct answer: Faster than maintenance only if signs of shock
In pediatric dehydration, ORT may require a bolus or increased rate if signs of hypovolemia/shock are present; otherwise, it matches or exceeds maintenance replacement – slower is inadequate in volume deficit.