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 medicines is expressed in mg per m2 of BSA). With respect to weight, the body surface area is a better indicator of metabolic mass, as it is less influenced by the amount of adipose tissue. In adults, moreover, the body surface area is approximately proportional to the glomerular filtration surface, to the volume, to the cardiac size. and other cardiological parameters.
The body surface area can be calculated indirectly on the basis of the equation of:
→ Mosteller (standard, because it is 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:
S. C. (m2) = 0.0003207 * Height (cm) 0.3 * Weight (g) (0.7285 - (0.0188 x LOG (g))
→ or based on specific nomograms:
(Click to enlarge)
Body surface and heat dispersion
The greater the body surface, the greater is the dispersion of heat (which occurs mainly at this level).
Extension of some body surfaces
- Skin = 2 square meters
- Respiratory tracts = 80-100 square meters
- Urogenital tract = 60-80 square meters
- Gastrointestinal tract = 300-600 m2
For this reason, nature wisely made Eskimos develop particularly short legs (smaller body surface), with a stocky structure (greater heat production), as opposed to blacks, who have long arms and legs to disperse more heat and a short bust to produce less.
Body surface and metabolism
The basal metabolism increases as the body surface increases (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 one of equal weight, but of considerably lower stature.
Basal metabolic rate can be calculated on the basis of body surface area using the:
Fleisch's formula
BMR (male) = 24 * BSA * {35.5 - 0.064 * [age (years) - 20]}
BMR (female) = 24 * BSA * {38 - 0.073 * [age (years) - 20]}
