The normal levels of sodium in plasma are?

Appeared in: ESIC Nursing Officer - 2019 (Shift-2)

Explanation

The accepted normal range for serum sodium in adults is 135 to 145 mEq/L.
Sodium is the most abundant cation in the extracellular fluid (ECF) and is the primary determinant of ECF volume and osmolality.
It plays a crucial role in controlling water distribution, maintaining fluid balance, and enabling nerve impulse transmission and muscle contraction.

Option B: This range, 97-106 mEq/L, represents the normal serum level for chloride (Cl⁻), not sodium.
Option C: This range is not a standard reference range for any common electrolyte. The unit mg/100ml is also less commonly used for electrolytes than mEq/L.
Option D: This range, 60-100 mg/dL, represents a typical range for fasting blood glucose.

Visual 1: Chart: A comparative chart displaying the normal ranges for key serum electrolytes (Sodium, Potassium, Chloride, Calcium, Magnesium) and other common lab values like glucose and BUN. This helps in memorizing and differentiating the values.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Normal Laboratory Values for Serum Electrolytes as background academic context rather than a clinical decision trigger.
Nurses must constantly monitor lab results for sodium imbalances, as both hyponatremia and hypernatremia can cause significant neurological changes and pose a safety risk (e.g., confusion, seizures, falls).
Patient education is vital. Nurses should instruct patients on sodium-restricted diets or those needing sodium replacement about dietary sources and the importance of adherence.
What if? If a patient is on a diuretic like furosemide, the nurse must be extra vigilant in monitoring for hyponatremia, as loop diuretics promote sodium excretion. An order for a salt-restricted diet in this patient would further increase the risk.

How to Approach the Question

First, identify the core of the question: it is a factual recall question asking for a specific normal laboratory value.
Recall the normal range for serum sodium. The most common range taught is 135-145 mEq/L.
Examine the options provided. Option A directly matches the known normal range for sodium.
To confirm, analyze the other options. Recognize that 97-106 mEq/L is the range for chloride and 60-100 mg/dL is for glucose. This process of elimination reinforces the correct answer.
Note the units. Electrolytes like sodium, potassium, and chloride are typically measured in mEq/L, while glucose is measured in mg/dL. This can be another clue to eliminate incorrect options.

Concept Tested & Keywords

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Practise the full ESIC Nursing Officer - 2019 (Shift-2)

Attempt every question from this paper in a timed mock, then review the full solution for each one.