A patient presents with serum sodium level 150 mEq/L and a history of persistent vomiting. What is the most likely fluid and electrolyte imbalance?

1. A

   Euvolemic hyponatremia

2. B

   Hypovolemic hyponatremia

3. C

   Hypervolemic hyponatremia

4. D

   Hypovolemic hypernatremia

Appeared in: NORCET 10 Mains

Explanation

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• The patient's serum sodium of 150 mEq/L is elevated above the normal range of 135-145 mEq/L, which defines hypernatremia.
• Persistent vomiting causes extrarenal fluid loss. This leads to a state of volume depletion, known as hypovolemia.
• In vomiting, the loss of hypotonic gastrointestinal fluids results in a greater deficit of water compared to sodium, concentrating the remaining sodium in the extracellular fluid.
• The combination of high sodium (hypernatremia) and volume depletion due to fluid loss (hypovolemia) correctly identifies the condition as hypovolemic hypernatremia.

Why Other Options Were Wrong

• Option A: This is incorrect because the patient has hypernatremia (high sodium), not hyponatremia (low sodium).
• Option B: This is incorrect because the patient's serum sodium is high (150 mEq/L), indicating hypernatremia, not hyponatremia.
• Option C: This is incorrect as the patient has hypernatremia (high sodium), not hyponatremia (low sodium), and is volume depleted, not volume overloaded.

Related Visual

Clinical Relevance

• Nursing practice connection: Knowing Identification of fluid and electrolyte imbalances based on lab values and clinical presentation helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Nurses must be able to quickly interpret lab values like serum sodium in the context of a patient's clinical signs (e.g., vomiting) to identify life-threatening electrolyte imbalances.
• Hypovolemic hypernatremia requires careful fluid replacement. The nursing priority is to restore volume with an appropriate IV solution (often isotonic saline initially, followed by a hypotonic solution) while monitoring sodium levels closely to prevent rapid correction, which can cause cerebral edema.
• What if? If the patient's sodium was 125 mEq/L instead of 150 mEq/L, the correct answer would be Hypovolemic Hyponatremia (Option B), as the vomiting would still cause hypovolemia, but the lab value would indicate low sodium.

How to Approach the Question

• First, analyze the laboratory value provided. The serum sodium is 150 mEq/L. Compare this to the normal range (135-145 mEq/L). This value is high, so the condition involves 'hypernatremia'.
• This initial step immediately eliminates all options involving 'hyponatremia' (Options A, B, and C).
• Next, analyze the clinical sign. The patient has a history of 'persistent vomiting'. Vomiting causes a loss of body fluids, leading to a decreased volume state, or 'hypovolemia'.
• Combine the two findings: 'hypernatremia' and 'hypovolemia'.
• Select the option that matches this combination, which is 'Hypovolemic hypernatremia'.

Concept Tested & Keywords

• Concept Tested: Identification of fluid and electrolyte imbalances based on lab values and clinical presentation.
• Stem keywords: serum sodium level 150 mEq/L, persistent vomiting
• Lead-in keywords: most likely
• Clinical cues: Serum sodium 150 mEq/L indicates hypernatremia (normal: 135-145 mEq/L).
• Clinical cues: Persistent vomiting is a cause of fluid volume loss (hypovolemia).

Question ID

QZUN0O4OX6HzZnFtCYMJCX

Copy ID

Reference Book

E6 Medicine Harrison 22e Part 1 pp. 388-390, 389-391