A patient is prescribed 6 units of insulin. The available insulin concentration is 100 units in 100 ml. How many ml should the nurse administer?

1. A

   0.6 ml

2. B

   1 ml

3. C

   6 ml

4. D

   60 ml

Appeared in: NORCET 9 Mains - 2025

Explanation

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• derived using the standard dosage calculation formula: (Desired Dose / Dose on Hand) × Quantity = Amount to Administer.
• Substituting the given values: (6 units / 100 units) × 100 ml results in 6 ml.
• A simpler way to conceptualize this is by recognizing that the available concentration of 100 units in 100 ml is equivalent to 1 unit per 1 ml.
• Therefore, to administer the prescribed 6 units, the nurse must draw up 6 ml of the solution.

Why Other Options Were Wrong

• Option A: This value would be obtained if the calculation was (6 units / 100 units) * 10 ml, or if the concentration was 10 units/ml (e.g., 100 units in 10 ml).
• Option B: This volume represents the amount needed for a single unit of insulin (1 ml contains 1 unit), not the prescribed dose of 6 units.
• Option D: This represents a tenfold medication error and would result in a significant overdose. This might occur if the decimal point was misplaced during calculation (e.g., 6.0 becoming 60).

Related Visual

• Visual 1: Diagram - A visual breakdown of the dosage calculation formula (D/H x Q) with the values from the question plugged in, showing how the units cancel out to leave the answer in ml.
• Visual 2: Infographic - An infographic comparing a standard U-100 insulin vial (100 units/ml) next to a 100 ml IV bag labeled '100 units of Insulin', visually demonstrating the difference between concentrated and diluted forms.

Clinical Relevance

• Nursing practice connection: Use the key finding related to Dosage Calculation for Liquid Medications to guide bedside assessment, documentation, and the next nursing action.
• Accurate dosage calculation is a fundamental nursing skill and a critical component of the 'Five Rights' of medication administration (Right Patient, Right Drug, Right Dose, Right Route, Right Time).
• Insulin is a high-alert medication, meaning errors can have serious consequences. All insulin calculations should be double-checked by another nurse before administration to prevent patient harm.
• What if? If the available insulin was from a standard U-100 vial (100 units/ml), the calculation would be (6 units / 100 units) x 1 ml = 0.06 ml. This tiny volume is difficult to measure accurately with a standard syringe, which is why diluted solutions are used for smaller doses, especially in IV infusions.

How to Approach the Question

• First, identify the three essential pieces of information from the question: the Desired dose (D), the Dose on Hand (H), and the Quantity or Volume (Q).
• In this case: D = 6 units, H = 100 units, Q = 100 ml.
• Select the appropriate dosage calculation formula: (D / H) × Q.
• Substitute the identified values into the formula: (6 / 100) × 100.
• Perform the calculation to find the final volume in ml.
• Always double-check your math and ensure the answer makes logical sense. A quick mental check is that since the concentration is 1 unit/ml, 6 units should equal 6 ml.

Concept Tested & Keywords

• Concept Tested: Dosage Calculation for Liquid Medications
• Stem keywords: prescribed, 6 units, insulin, concentration, 100 units in 100 ml
• Lead-in keywords: How many ml
• Clinical cues: The concentration '100 units in 100 ml' simplifies to 1 unit/ml, which is a key step in the calculation.

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