Body surface area

In physiologyand medicine, the body surface area (BSA) is the measured or calculated surface of a human body. For many clinical purposes BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass. Estimation of BSA is simpler than many measures of volume.

Uses

Examples of uses of the BSA:

• Renal functionis usually fractioned over the BSA to gain an appreciation of the true required glomerular filtration rate(GFR);
• The Quetelet indexuses a somewhat modified form of the BSA;
• The cardiac indexis a measure of cardiac outputdivided by the BSA, giving a better approximation of the required cardiac output;
• Chemotherapyis often dosed according to the patient's BSA.
• Glucocorticoiddosing is also expressed in terms of BSA for calculating maintenance doses or to compare high dose use with maintenance requirement.

Calculation

Various calculations have been published to arrive at the BSA without direct measurement, starting in 1916with the Dubois & Dubois formula. A commonly used formula is the Mosteller formula, published in 1987:

Metric (area in square metres from weightin kilogramsand heightin centimetres):

<math>{x}= \sqrt\frac{\mbox{weight} \times \mbox{height} }{3600}</math>

half-English units(area in square metres from weightin pounds, height in inches):

<math>{x}= \sqrt\frac{\mbox{weight} \times \mbox{height} }{3125}</math>

Another is the Haycock formula (in children):

<math>{x}=0.024265 \times {weight \mbox{ (kg)}}^{0.5378} \times {height \mbox{ (cm)}}^{0.3964}</math>,

Du Bois & Du Bois, Arch. intern. Med., 17,863 (1916):

<math>{x}=(71.84 \times {weight \mbox{ (kg)}}^{0.425} \times {height \mbox{ (cm)}}^{0.725})/10000</math>,

Gehan EA, George SL, Cancer Chemother Rep 1970;54:225-235:

<math>\mathrm{S} = 0.0235 \times height \mbox{ (cm)}^{0.42246} \times weight \mbox{ (kg)}^{0.51456}</math> ,

Boyd's Formula:

<math>\mathrm{S} = 0.0003207

\times height \mbox{ (cm)}^{0.3} \times (weight \mbox{ (kg)} \times 1000)^{(0.7285 - 0.564 \lg{weight \mathrm{ (kg)}})}</math>.

Normal values

• "Normal" BSA is generally taken to be 1.7 m².
• Average BSA for men: 1.9 m²
• Average BSA for women: 1.6 m²
• Average BSA for child (9 years): 1.07 m²
• Average BSA for child (10 years): 1.14 m²
• Average BSA for child (12-13 years): 1.33 m²

References

• Mosteller RD. Simplified calculation of body-surface area. N Engl J Med1987;317:1098. PMID 3657876.
• Haycock GB, Schwartz GJ, Wisotsky DH Geometric method for measuring bodz surface area: A height-weight formula validated in infants, children and adults J Pediatr 1978;93:62-66

External link

• BC Cancer networkBSA calculation guidelines.de:Körperoberfläche

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Body+surface+area Wikipedia article Body surface area.