MSNCB Fluid & Electrolyte Balance 1 — Questions and Answers
Question 1: A patient's serum sodium level is 128 mEq/L. Which condition does this reflect?
- Hypernatremia
- Hyponatremia (Correct answer)
- Hyperkalemia
- Hypokalemia
Correct answer: Hyponatremia
Hyponatremia is defined as a serum sodium level below 135 mEq/L, making 128 mEq/L a clear indicator of this imbalance.
Question 2: A nurse assesses a patient and finds muscle weakness, fatigue, and ECG changes showing flattened T waves with prominent U waves. Which electrolyte imbalance is most likely?
- Hypernatremia
- Hypercalcemia
- Hypokalemia (Correct answer)
- Hypermagnesemia
Correct answer: Hypokalemia
Hypokalemia causes muscle weakness, fatigue, and characteristic ECG changes including flattened T waves and prominent U waves due to altered myocardial repolarization.
Question 3: Which IV solution is classified as isotonic?
- 0.45% NaCl
- 3% NaCl
- 0.9% NaCl (Correct answer)
- D10W
Correct answer: 0.9% NaCl
0.9% NaCl (normal saline) has an osmolarity of approximately 308 mOsm/L, matching plasma osmolarity and making it isotonic.
Question 4: A patient with heart failure presents with bilateral lung crackles, peripheral edema, and a 4-pound weight gain in 2 days. Which fluid imbalance does this represent?
- Fluid volume deficit
- Third spacing
- Fluid volume excess (Correct answer)
- Isotonic dehydration
Correct answer: Fluid volume excess
Bilateral crackles, peripheral edema, and rapid weight gain are hallmark signs of fluid volume excess (hypervolemia) due to sodium and water retention.
Question 5: A patient with prolonged vomiting and nasogastric suction is at greatest risk for which acid-base imbalance?
- Metabolic acidosis
- Respiratory acidosis
- Metabolic alkalosis (Correct answer)
- Respiratory alkalosis
Correct answer: Metabolic alkalosis
Loss of hydrochloric acid through vomiting or NG suction removes hydrogen ions from the body, resulting in metabolic alkalosis.
Question 6: Which assessment finding is most indicative of dehydration in an adult patient?
- Bounding peripheral pulses
- Decreased skin turgor (Correct answer)
- Jugular vein distension
- Peripheral edema
Correct answer: Decreased skin turgor
Decreased skin turgor (tenting) occurs when interstitial fluid is depleted, making it a reliable clinical indicator of dehydration.
Question 7: A nurse is caring for a patient with hypernatremia (serum sodium 158 mEq/L). Which intervention is most appropriate?
- Administer 3% NaCl IV
- Encourage free water intake or administer hypotonic fluids (Correct answer)
- Restrict all fluid intake
- Administer sodium bicarbonate
Correct answer: Encourage free water intake or administer hypotonic fluids
Hypernatremia is treated by replacing the free water deficit using hypotonic fluids or encouraging oral water intake to dilute the elevated serum sodium level.
MSNCB Fluid & Electrolyte Balance 1
A patient's serum sodium level is 128 mEq/L.
Which condition does this reflect?