Body surface area
From Wikipedia, the free encyclopedia
In physiology and 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.
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[edit] Uses
Examples of uses of the BSA:
- Renal function is usually fractioned over the BSA to gain an appreciation of the true required glomerular filtration rate (GFR);
- The Quetelet index uses a somewhat modified form of the BSA;
- The cardiac index is a measure of cardiac output divided by the BSA, giving a better approximation of the required cardiac output;
- Chemotherapy is often dosed according to the patient's BSA.
- Glucocorticoid dosing is also expressed in terms of BSA for calculating maintenance doses or to compare high dose use with maintenance requirement.
[edit] Calculation
Various calculations have been published to arrive at the BSA without direct measurement:
The Dubois & Dubois formula:[1]:
or alternatively expressed:
One commonly used formula is the Mosteller formula, published in 1987[2] and adopted for use by the Pharmacy and Therapeutics Committee of the Cross Cancer Institute, Edmonton, Alberta, Canada:
Other formulas include the Haycock formula[3]:
the Gehan and George formula[4]:
the Boyd formula[5]:
[edit] Normal values
"Normal" BSA is generally taken to be 1.73 m² for an adult.
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Average BSA values Neonate 0.25 m² Child 2 years 0.5 m² Child 9 years 1.07 m² Child 10 years 1.14 m² Child 12-13 years 1.33 m² For men 1.9 m² For women 1.6 m²
[edit] References
- ^ Du Bois & Du Bois,Arch Intern Med 1916, 17:863
- ^ Mosteller RD. "Simplified calculation of body-surface area". N Engl J Med 1987; 317:1098. PMID 3657876.
- ^ Haycock GB, Schwartz GJ, Wisotsky DH "Geometric method for measuring body surface area: A height-weight formula validated in infants, children and adults" J Pediatr 1978, 93:62-66.
- ^ Gehan EA, George SL, Cancer Chemother Rep 1970, 54:225-235
- ^ http://www.ispub.com/journals/IJA/Vol2N2/bsa.htm (from Boyd E, The growth of the surface area of the human body. Minneapolis: University of Minnesota Press, 1935.)
