1. What is Adjusted Body Weight?

Definition: Adjusted body weight (ABW) is a calculation used in medicine to estimate a more accurate body weight for drug dosing in obese patients.

Purpose: It provides a better estimate of metabolic mass than total body weight or ideal body weight alone, especially for medications that distribute differently in adipose tissue.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Adjusted BW — Adjusted body weight (kg)
• IBW — Ideal body weight (kg)
• Actual BW — Actual body weight (kg)

Explanation: The formula accounts for 40% of the difference between actual and ideal body weight, recognizing that some medications distribute partially into adipose tissue.

3. Importance of Adjusted Body Weight

Details: Using adjusted body weight helps prevent overdosing in obese patients while still accounting for their increased mass, particularly important for drugs like aminoglycosides and some chemotherapeutic agents.

4. Using the Calculator

Tips: Enter the patient's ideal body weight (calculated separately) and actual body weight in kilograms. Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: When should I use adjusted body weight?
A: Use ABW for dosing medications in obese patients (typically BMI ≥30) when the drug has limited distribution into adipose tissue.

Q2: How do I calculate ideal body weight?
A: For men: 50 kg + 2.3 kg per inch over 5 feet. For women: 45.5 kg + 2.3 kg per inch over 5 feet.

Q3: Why is the factor 0.4 used?
A: Research shows many drugs distribute into about 40% of excess weight beyond IBW in obese patients.

Q4: Are there drugs that require different adjustment factors?
A: Yes, some medications may use factors from 0.3 to 0.5 depending on their pharmacokinetics.

Q5: Should I use ABW for all obese patients?
A: No, consult specific drug guidelines as some medications require dosing based on actual weight or IBW.