Body Surface Area Calculation Methods
The Mosteller formula (BSA (m²) = √[(Height(cm) × Weight(kg))/3600]) is recommended for routine clinical use due to its simplicity and accuracy. 1
Recommended BSA Formulas
The calculation of body surface area (BSA) is essential in many clinical contexts, including medication dosing, cardiac parameter indexing, and renal function assessment. Several validated formulas exist:
Mosteller Formula (Preferred for routine clinical use):
- BSA (m²) = √[(Height(cm) × Weight(kg))/3600]
- Advantages: Simple to calculate, accurate across populations 1
Gehan and George Formula (Alternative, especially for pediatrics):
- BSA (m²) = 0.0235 × (height [cm])^0.42246 × (weight [kg])^0.51456
- Can also be expressed as: BSA (m²) = 0.007184 × Height(cm)^0.725 × Weight(kg)^0.425
- Advantages: Derived from a larger sample size, particularly useful in pediatric settings 1
Clinical Applications of BSA
BSA calculations are critical in multiple medical contexts:
- Medication dosing: Particularly important for chemotherapeutic agents and medications with narrow therapeutic indices 1
- Cardiac parameter indexing: The European Heart Society recommends using BSA to index left ventricular size parameters 2, 1
- Valvular heart disease management: Critical for timing surgical interventions in conditions like aortic regurgitation (e.g., LVESD >25 mm/m² BSA) 2
- Renal function assessment: GFR is typically normalized to 1.73 m² BSA for staging chronic kidney disease 1
- Aortic dimensions: BSA indexing helps identify aortic dilatation (ascending thoracic aorta >22 mm/m² or DTA >16 mm/m²) 2
Important Considerations and Limitations
- Formula discrepancies: Differences between BSA formulas can reach up to 0.5 m² for standard adult physique, potentially affecting clinical decisions 3
- Obesity considerations: Traditional formulas like DuBois may underestimate BSA in obese patients by 3-5% 4
- Special populations: Women and patients with smaller stature may require special attention when BSA calculations are used for clinical decision-making 1
- Height estimation: When height measurement is unavailable, standard growth charts can be used to estimate height based on weight, particularly in pediatric patients 1
Practical Recommendations
- For routine clinical use, employ the Mosteller formula due to its simplicity and accuracy 1
- For research purposes, consider the Gehan and George formula due to its statistical robustness 1
- When following patients over time, use the same formula consistently to avoid introducing artificial changes 2
- Be aware that indexing aortic diameters to BSA, along with nomograms and z-scores, provides more accurate assessment of aortic size, especially for patients with smaller body size 2
When making clinical decisions based on BSA-indexed parameters, consider the patient's overall clinical picture and be aware that different formulas may yield different results, potentially affecting treatment decisions in critical applications like chemotherapy dosing or timing of cardiac interventions.