Talk:Body surface area

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The following sentence contains a logical contradiction and should be clarified or corrected:

In various studies, it has been found to approximate the body's volume better than the actual measure of the body volume. This has led to wide applications of the BSA in medicine.

This has been corrected. Thank you, Paul, for fixing the error in the formula! JFW | T@lk 09:43, 31 May 2004 (UTC)

[edit] Error?

The formula using half-english units on this page has a base number, under the square root, of 3125, but when I went to the BC Cancer Network link on the bottom of the page, the formula had a base of 3131, so I was wondering which number is correct.

Two of my texts, as well as numerous online sources use 3131. I could only find one online source showing 3125 so made the change. 71.33.200.105 18:51, 29 October 2007 (UTC)

Per [Mostller, R.D., (1987). Simplified calculation of body-surface area. The NEW ENGLAND JOURNAL of MEDICINE, 317, 1098.] the correct number is 3131 for half-english calculations. I have no idea where 3125 keeps coming from but it's not part of Dr. Mosteller's formula. 63.224.82.78 16:38, 2 November 2007 (UTC)


Where the 3125 comes from is a simple conversion of the number 3600 from metric to English units:

3600 * (kg-to-lb-conversion-factor * cm-to-in-conversion-factor) = 3600 * 2.204622 * 0.3937008 = 3124.662

I have not been able to obtain Mosteller's original paper, so do not know which of the numbers, 3600 or 3131, appears there; various references on the Web lead me to believe that it must be the 3131 number. If this is the case (i.e., the correct formula for BSA in half-English units is in fact \sqrt\frac{\mbox{weight} \times \mbox{height} }{3131}), then the formula in purely metric units should not be \sqrt\frac{\mbox{weight} \times \mbox{height} }{3600}, but rather \sqrt\frac{\mbox{weight} \times \mbox{height} }{3607}.

It is disturbing that the two incompatible numbers, 3131 and 3600, appear in the literature, but it is actually academic: the choice of 3131 versus 3125 as the divisor in the formula corresponds to a 0.1% difference in the resulting BSA value, which is much too small to be of importance in anything for which BSA calculation is normally used.
Greg Lutz 09:29, 11 November 2007 (UTC)

I'm not in a position to dispute your calculations but Mosteller's paper, which I have in hand, lists the divisor both as 3600 for metric units and as 3131 for half-english units. If you're interested, reply here and I'll dig up a paper I found on the web that shows Dr. Mosteller's calculation only placing third as far as accuracy in calculation of BSA but, due to its ease of use, it has won widespread (nigh universal) acceptance. Overall, the error is usually less than 2% from measured BSA and significantly more accurate than DuBois' for peds. As an aside, I have four Palm-based BSA calculators and three of them use DuBois' formula which is arguably the least accurate means of calculation. The remaining one uses Mosteller's formula but converts English units to metric prior to using the SQRT( ((H * W)/3600) ) formula. Guess there's something to be said for longevity. Regards, TK 216.160.159.169 23:40, 12 November 2007 (UTC)