1. What is Body Surface Area (BSA) for Methotrexate Dosing?

Definition: BSA is a calculated measurement of the total surface area of the human body, used to determine appropriate drug dosages like methotrexate.

Purpose: It provides a more accurate dosing parameter than body weight alone, especially for chemotherapy drugs and medications with narrow therapeutic windows.

2. How Does the Mosteller Formula Work?

The calculator uses the Mosteller formula:

Where:

• \( BSA \) — Body Surface Area (square meters)
• \( W \) — Weight (kilograms)
• \( H \) — Height (centimeters)

Explanation: This formula provides a simple yet accurate way to estimate body surface area from weight and height measurements.

3. Importance of BSA in Methotrexate Dosing

Details: Methotrexate dosing based on BSA helps achieve therapeutic levels while minimizing toxicity, as drug effects correlate better with body surface area than weight alone.

4. Using the Calculator

Tips: Enter the patient's weight in kilograms and height in centimeters. Both values must be > 0 for calculation.

5. Frequently Asked Questions (FAQ)

Q1: Why use BSA instead of weight for methotrexate?
A: BSA correlates better with metabolic rate and drug distribution than weight alone, especially for chemotherapy agents.

Q2: How accurate is the Mosteller formula?
A: It's within 1-2% of more complex formulas and is widely accepted in clinical practice.

Q3: When would BSA calculation be most important?
A: For high-dose methotrexate therapy, chemotherapy, and pediatric dosing where precise calculations are critical.

Q4: What's the typical BSA range for adults?
A: Average BSA is about 1.7 m² for adult women and 1.9 m² for adult men, with normal range approximately 1.4-2.2 m².

Q5: Are there other BSA formulas?
A: Yes, including DuBois, Haycock, and Boyd formulas, but Mosteller is simplest and equally accurate for clinical use.