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Conversion Formula:
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The mg/kg to mg/m² conversion is used to adjust medication doses based on body surface area (BSA) rather than body weight alone. This is particularly important in chemotherapy and pediatric dosing where BSA provides a more accurate measure of metabolic mass.
The calculator uses the following formula:
Where:
Explanation: The formula converts a weight-based dose to a body surface area-based dose, which often correlates better with metabolic rate and drug clearance.
Details: BSA-based dosing is particularly important for drugs with narrow therapeutic indices, where small dosing errors can lead to toxicity or treatment failure. It's widely used in oncology, pediatrics, and for certain antibiotics.
Tips: Enter the weight-based dose in mg/kg, the patient's weight in kilograms, and the calculated body surface area in m². All values must be positive numbers.
Q1: Why use BSA instead of weight for dosing?
A: BSA correlates better with metabolic processes, blood volume, and organ size than body weight alone, especially for drugs that distribute throughout body water or are metabolized by organs.
Q2: How is BSA calculated?
A: BSA is typically calculated using formulas like Mosteller, Du Bois, or Haycock, based on height and weight measurements.
Q3: When is weight-based dosing preferred?
A: Weight-based dosing is typically used for drugs that distribute in body water or fat, or for patients with extreme body compositions.
Q4: Are there limitations to BSA dosing?
A: BSA dosing may not be optimal for obese patients, as it can lead to underdosing. Alternative approaches like adjusted body weight or capped doses may be used.
Q5: What's the typical range for BSA in adults?
A: Average BSA is about 1.7 m² for adult men and 1.6 m² for adult women, typically ranging from 1.4-2.2 m².