The body surface area (BSA, from the English Body Surface Area ) is a very important anthropometric parameter; knowing it, it is possible to draw up specific nutritional or pharmacotherapeutic programs (the dosage of certain drugs is expressed in mg per m2 of BSA). Compared to weight, the body surface area represents a better indicator of the metabolic mass, since it is less influenced by the quantity of adipose tissue. In adults, moreover, the body surface is approximately proportional to the glomerular filtration surface, to the volume, to the cardiac dimensions and to other cardiological parameters.
The body surface area can be calculated indirectly based on the equation of:
→ Mosteller (standard, because easy to remember):
Body Surface Area (m2) = [(Height (cm) X Weight (kg) / 3600)] 1/2
→ DuBois and DuBois :
Body Surface Area (m2) = 0.202 * (Height (m) 0.725 * Weight (kg) 0.425)
Body Surface Area (m2) = 0.007184 * (Height (cm) 0.725 * Weight (kg) 0.425)
→ Haycock (in children):
Body Surface Area (m2) = 0.024265 * Height (cm) 0.3964 * Weight (kg) 0.5378
→ Gehan and George :
Body Surface Area (m2) = 0.0235 * Height (cm) 0.42246 * Weight (kg) 0.51456
→ Boyd :
SC (m2) = 0.0003207 * Height (cm) 0.3 * Weight (g) (0.7285 - (0.0188 x LOG (g))
→ or based on specific nomograms:
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Body surface and heat dispersion
The larger the body surface, the more heat is dispersed (which occurs mainly at this level).
Extension of some body surfaces
- Skin = 2 square meters
- Respiratory tract = 80-100 square meters
- Urogenital tract = 60-80 square meters
- Gastrointestinal tract = 300-600 m2
For this reason nature has wisely made sure that the Eskimos developed particularly short legs (less body surface), with a stocky structure (greater heat production), unlike blacks, which have long arms and legs to disperse more heat and a short bust to produce less.
Body surface and metabolism
The basal metabolic rate increases with the increase of the body surface (for this reason it is normally expressed in Kcal / m2 / hour). This is a very important observation, since a diet suitable for a long-limbed person (long limbs), becomes fattening if proposed to another of equal weight, but of considerably lower stature.
The basal metabolic rate can be calculated based on the body surface using the:
Fleisch formula
BMR (male) = 24 * BSA * {35.5 - 0.064 * [age (years) - 20]}
BMR (woman) = 24 * BSA * {38 - 0.073 * [age (years) - 20]}
