A 60-year-old patient presents with lethargy and muscle weakness. Laboratory results reveal serum sodium of 150 mEq/L and potassium of 5 mEq/L. What is the most appropriate initial management?

1. A

   Administer 3% hypertonic saline

2. B

   Initiate intravenous 5% dextrose in water (D5W)

3. C

   Begin intravenous 0.9% normal saline with potassium chloride supplementation

4. D

   Restrict fluid intake

Appeared in: NORCET 8 Prelims-2025

Explanation

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• The patient has hypernatremia (sodium > 145 mEq/L), which causes cellular dehydration, leading to symptoms like lethargy and weakness.
• The primary treatment for hypernatremia is to replace the free water deficit.
• Intravenous 5% dextrose in water (D5W) is an isotonic solution that becomes hypotonic in the body after the dextrose is metabolized.
• This provides free water, which dilutes the elevated serum sodium and corrects the hyperosmolar state.
• This is the standard treatment for euvolemic or hypervolemic hypernatremia when the patient cannot take oral fluids.

Why Other Options Were Wrong

• Option A: This is a hypertonic solution containing a high concentration of sodium. Administering it would severely worsen the patient's hypernatremia and cellular dehydration.
• Option C: 9% Normal Saline is an isotonic solution and will not effectively lower the serum sodium level compared to a hypotonic solution. More importantly, the patient's potassium is 5.0 mEq/L (high-normal), so adding potassium chloride (KCl) is contraindicated as it could easily induce life-threatening hyperkalemia.
• Option D: Fluid restriction is a treatment for hyponatremia caused by excess body water (e.g., Syndrome of Inappropriate Antidiuretic Hormone - SIADH). In hypernatremia, the patient has a water deficit, and restricting fluids would exacerbate the condition.

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Clinical Relevance

• Nursing practice connection: Knowing Management of Hypernatremia helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Rapid correction of hypernatremia is dangerous. Lowering sodium too quickly (faster than 0.5-1 mEq/L/hr) can cause a rapid shift of water into brain cells, leading to cerebral edema, seizures, permanent brain damage, or death.
• Nurses must meticulously monitor neurological status, vital signs, and serum sodium levels during treatment to ensure the correction rate is safe.
• What if the patient also had a blood pressure of 80/50 mmHg and a heart rate of 120 bpm? In this case of hypovolemic hypernatremia, the priority would shift to volume resuscitation first. The nurse would administer 0.9% Normal Saline to stabilize the blood pressure before switching to a hypotonic fluid like D5W to correct the free water deficit.

How to Approach the Question

• First, analyze the patient's clinical presentation and laboratory values. Identify the primary electrolyte imbalance: serum sodium is 150 mEq/L, which is hypernatremia.
• Note the secondary lab value: potassium is 5.0 mEq/L, which is at the upper limit of normal.
• Understand the pathophysiology of the primary imbalance. Hypernatremia means there is too much sodium relative to water, causing water to shift out of cells, leading to cellular dehydration.
• Determine the treatment goal: The goal is to replace the free water deficit and slowly lower the serum sodium.
• Evaluate each option against this goal. D5W provides free water. 3% saline adds more sodium. 0.9% NS is isotonic and won't correct the free water deficit effectively, and the added potassium is dangerous. Fluid restriction would worsen the dehydration.
• Select the option that safely and effectively achieves the treatment goal, which is the administration of a hypotonic fluid.

Concept Tested & Keywords

• Concept Tested: Management of Hypernatremia
• Stem keywords: hypernatremia, serum sodium 150 mEq/L, potassium 5 mEq/L, lethargy, muscle weakness
• Lead-in keywords: most appropriate initial management
• Clinical cues: Serum sodium of 150 mEq/L indicates hypernatremia.
• Clinical cues: Potassium of 5.0 mEq/L is at the upper limit of normal, making potassium supplementation risky.

Question ID

Q-5iKh-273ZwUzX21WyrFB

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Reference Book

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 1 p. 148-150

E6 Pharmacology Nursing Lilley 11e Part 2 p. 171-173