5% dextrose is?

ISRO- 2016

Nursing Foundation

Hard

Appeared in: ISRO- 2016

Explanation

5% Dextrose in water (D5W) is classified as an isotonic solution because its initial osmolarity (approximately 252 mOsm/L) is similar to that of blood plasma (275-295 mOsm/L).
This classification refers to the state of the fluid within the IV bag before it is administered to the patient.
While it is isotonic in the bag, it exerts a hypotonic effect in the body once the dextrose is metabolized, leaving free water.
The key differentiator is understanding the difference between a fluid's classification in the bag versus its physiological effect in the body. For a direct classification question, the 'in the bag' tonicity is the standard answer.

Option B: Normotonic is a synonym for isotonic. While technically correct, 'isotonic' is the standard and more widely used term in clinical practice and nursing education.
Option C: Hypertonic solutions have a higher osmolarity than plasma (e.g., D10W, 3% NaCl). They pull fluid out of cells. D5W has an osmolarity similar to plasma, not higher.
Option D: This is a very close distractor. While D5W has a hypotonic effect in the body, its classification as a solution in the IV bag is isotonic. A true hypotonic solution, like 0.45% NaCl, has an osmolarity lower than plasma from the start.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Tonicity of Intravenous (IV) Solutions as background academic context rather than a clinical decision trigger.
Nurses must understand that D5W provides 'free water' and acts as a hypotonic solution in the body. This is critical for patient safety, as administering it to a patient with increased intracranial pressure (ICP) can worsen cerebral edema.
D5W is often used to treat hypernatremia because it provides water to dilute the high sodium concentration in the blood without adding more electrolytes.
What if? If a patient needed rapid intravascular volume expansion due to hypovolemic shock, D5W would be a poor choice. Because it becomes hypotonic and fluid shifts into the cells, it does not effectively expand the plasma volume. An isotonic solution like 0.9% Normal Saline or Lactated Ringer's would be the correct choice.

How to Approach the Question

First, identify the core of the question, which is asking for the classification of 5% dextrose solution.
Recognize that this is a common factual recall question in nursing that tests a specific clinical nuance.
Recall the definitions of isotonic, hypotonic, and hypertonic based on their osmolarity relative to blood plasma.
Remember the special case of D5W: it is isotonic in the IV bag but becomes physiologically hypotonic in the body after the dextrose is metabolized.
For a direct classification question like this, the standard answer refers to the solution's state before administration (in the bag).
Select 'Isotonic' as the correct classification, while keeping in mind its important hypotonic effect for clinical application.

Concept Tested & Keywords

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