Body surface area

In physiology and medicine, the body surface area (BSA) is the measured or calculated surface area 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. Nevertheless, there have been several important critiques of the use of BSA in determining the dosage of medications with a narrow therapeutic index, such as chemotherapy.

Typically, there is a 4–10-fold variation in drug clearance between individuals due to differing the activity of drug elimination processes related to genetic and environmental factors. This can lead to significant overdosing and underdosing (and increased risk of disease recurrence). It is also thought to be a distorting factor in Phase I and II trials that may result in potentially helpful medications being prematurely rejected. The trend to personalized medicine is one approach to counter this weakness.

Uses

Examples of uses of the BSA:

Renal clearance usually divided by the BSA i.e. per 1.73 m² to gain an appreciation of the true 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 effective 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.

There is some evidence that BSA values are less accurate at extremes of height and weight, where Body Mass Index may be a better estimate (for hemodynamic parameters).

Calculation

Various calculations have been published to arrive at the BSA without direct measurement. In the following formulae, M is the subject's mass, and H is the subject's height.

The most widely used is the Du Bois formula, which has been shown to be equally as effective in estimating body fat in obese and non-obese patients, something the Body mass index fails to do.

{\displaystyle {BSA}=a imes M^{0.425} imes H^{0.725 <semantics><mrow><mstyle><mrow><mi>B</mi><mi>S</mi><mi>A</mi></mrow><mo>=</mo><mi>a</mi><mo>×</mo><msup><mi>M</mi><mrow><mn>0.425</mn></mrow></msup><mo>×</mo><msup><mi>H</mi><mrow><mn>0.725</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle {BSA}=a imes M^{0.425} imes H^{0.725}}</annotation></semantics></math></span><img src=

where

{\displaystyle a=71.84{cm}^{1.275}{kg}^{-0.425 <semantics><mrow><mstyle><mi>a</mi><mo>=</mo><mn>71.84</mn><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>1.275</mn></mrow></msup><msup><mrow><mi>k</mi><mi>g</mi></mrow><mrow><mo>−</mo><mn>0.425</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle a=71.84{cm}^{1.275}{kg}^{-0.425}}</annotation></semantics></math></span><img src=

La formule de Mosteller est également couramment utilisée et est mathématiquement plus simple :

{\displaystyle {BSA}=b{\sqrt {M imes H <semantics><mrow><mstyle><mrow><mi>B</mi><mi>S</mi><mi>UN</mi></mrow><mo>=</mo><mi>b</mi><mrow><msqrt><mi>M</mi><mo>×</mo><mi>H</mi></msqrt></mrow></mstyle></mrow><annotation>{\displaystyle {BSA}=b{\sqrt {M imes H}}}</annotation></semantics></math></span><img src=

où

{\displaystyle b={\frac {1000}{6}}{cm}^{1.5}{kg}^{-0.5 <semantics><mrow><mstyle><mi>b</mi><mo>=</mo><mrow><mfrac><mn>1000</mn><mn>6</mn></mfrac></mrow><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>1.5</mn></mrow></msup><msup><mrow><mi>k</mi><mi>g</mi></mrow><mrow><mo>−</mo><mn>0,5</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle b={\frac {1000}{6}}{cm}^{1.5}{kg}^{-0.5}}</annotation></semantics></math></span><img src=

{\displaystyle {BSA}={\sqrt {\frac {{\mbox{height}} imes {\mbox{weight}}}{3600 <semantics><mrow><mstyle><mrow><mi>B</mi><mi>S</mi><mi>UN</mi></mrow><mo>=</mo><mrow><msqrt><mfrac><mrow><mrow><mstyle><mtext>hauteur</mtext></mstyle></mrow><mo>×</mo><mrow><mstyle><mtext>poids</mtext></mstyle></mrow></mrow><mn>3600</mn></mfrac></msqrt></mrow></mstyle></mrow><annotation>{\displaystyle {BSA}={\sqrt {\frac {{\mbox{height}} imes {\mbox{weight}}}{3600}}}}</annotation></semantics></math></span><img src=

D'autres formules pour la BSA incluent :

où

{\displaystyle c=242.65{cm}^{1.6036}{kg}^{-0.5378 <semantics><mrow><mstyle><mi>c</mi><mo>=</mo><mn>242,65</mn><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>1,6036</mn></mrow></msup><msup><mrow><mi>k</mi><mi>g</mi></mrow><mrow><mo>−</mo><mn>0,5378</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle c=242.65{cm}^{1.6036}{kg}^{-0.5378}}</annotation></semantics></math></span><img src=

{\displaystyle d=235{cm}^{1.57754}kg^{-0.51456 <semantics><mrow><mstyle><mi>d</mi><mo>=</mo><mn>235</mn><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>1,57754</mn></mrow></msup><mi>k</mi><msup><mi>g</mi><mrow><mo>−</mo><mn>0,51456</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle d=235{cm}^{1.57754}kg^{-0.51456}}</annotation></semantics></math></span><img src=

{\displaystyle e=333{cm}^{1.7 <semantics><mrow><mstyle><mi>e</mi><mo>=</mo><mn>333</mn><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>1.7</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle e=333{cm}^{1.7}}</annotation></semantics></math></span><img src=

{\displaystyle f=10^{\frac {0.6157}{0.0188}}kg <semantics><mrow><mstyle><mi>f</mi><mo>=</mo><msup><mn>10</mn><mrow><mfrac><mn>0,6157</mn><mn>0,0188</mn></mfrac></mrow></msup><mi>k</mi><mi>g</mi></mstyle></mrow><annotation>{\displaystyle f=10^{\frac {0.6157}{0.0188}}kg}</annotation></semantics></math></span><img src=

{\displaystyle g=88.83{cm}^{1.337}{kg}^{0.556 <semantics><mrow><mstyle><mi>g</mi><mo>=</mo><mn>88,83</mn><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>1,337</mn></mrow></msup><msup><mrow><mi>k</mi><mi>g</mi></mrow><mrow><mn>0,556</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle g=88.83{cm}^{1.337}{kg}^{0.556}}</annotation></semantics></math></span><img src=

{\displaystyle h=72.41{cm}^{1.275}{kg}^{-0.425 <semantics><mrow><mstyle><mi>h</mi><mo>=</mo><mn>72,41</mn><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>1,275</mn></mrow></msup><msup><mrow><mi>k</mi><mi>g</mi></mrow><mrow><mo>−</mo><mn>0,425</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle h=72.41{cm}^{1.275}{kg}^{-0.425}}</annotation></semantics></math></span><img src=

{\displaystyle i=94.9{cm}^{1.345}{kg}^{-0.441 <semantics><mrow><mstyle><mi>je</mi><mo>=</mo><mn>94,9</mn><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>1,345</mn></mrow></msup><msup><mrow><mi>k</mi><mi>g</mi></mrow><mrow><mo>−</mo><mn>0,441</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle i=94.9{cm}^{1.345}{kg}^{-0.441}}</annotation></semantics></math></span><img src=

{\displaystyle j=87.8108{cm}^{1.32156}{kg}^{-0.434972 <semantics><mrow><mstyle><mi>j</mi><mo>=</mo><mn>87,8108</mn><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>1,32156</mn></mrow></msup><msup><mrow><mi>k</mi><mi>g</mi></mrow><mrow><mo>−</mo><mn>0,434972</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle j=87.8108{cm}^{1.32156}{kg}^{-0.434972}}</annotation></semantics></math></span><img src=

{\displaystyle k=9.75482{cm}^{0.96}{kg}^{-0.46 <semantics><mrow><mstyle><mi>k</mi><mo>=</mo><mn>9,75482</mn><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>0,96</mn></mrow></msup><msup><mrow><mi>k</mi><mi>g</mi></mrow><mrow><mo>−</mo><mn>0,46</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle k=9.75482{cm}^{0.96}{kg}^{-0.46}}</annotation></semantics></math></span><img src=

{\displaystyle l=5.79479{cm}^{0.76}{kg}^{-0.38 <semantics><mrow><mstyle><mi>l</mi><mo>=</mo><mn>5,79479</mn><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>0,76</mn></mrow></msup><msup><mrow><mi>k</mi><mi>g</mi></mrow><mrow><mo>−</mo><mn>0,38</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle l=5.79479{cm}^{0.76}{kg}^{-0.38}}</annotation></semantics></math></span><img src=

Pour toute formule, les unités doivent correspondre. Lipscombe, suivant le raisonnement de Mosteller, a observé que les formules obtenues par Fujimoto, Shuter et Aslani, Takahira et Lipscombe suggèrent que… ${\displaystyle m imes M^{4/9} imes H^{2/3 <semantics><mrow><mstyle><mi>m</mi><mo>×</mo><msup><mi>M</mi><mrow><mn>4</mn><mrow><mo>/</mo></mrow><mn>9</mn></mrow></msup><mo>×</mo><msup><mi>H</mi><mrow><mn>2</mn><mrow><mo>/</mo></mrow><mn>3</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle m imes M^{4/9} imes H^{2/3}}</annotation></semantics></math><img src=$ ${\displaystyle {\frac {800}{9}}({\frac {kg}{{cm}^{3}}})^{-{\frac {4}{9 <semantics><mrow><mstyle><mrow><mfrac><mn>800</mn><mn>9</mn></mfrac></mrow><mo>(</mo><mrow><mfrac><mrow><mi>k</mi><mi>g</mi></mrow><msup><mrow><mi>c</mi><mi>m</mi></mrow><mrow><mn>3</mn></mrow></msup></mfrac></mrow><msup><mo>)</mo><mrow><mo>−</mo><mrow><mfrac><mn>4</mn><mn>9</mn></mfrac></mrow></mrow></msup></mstyle></mrow><annotation>{\displaystyle {\frac {800}{9}}({\frac {kg}{{cm}^{3}}})^{-{\frac {4}{9}}}}</annotation></semantics></math><img src=$

Une formule basée sur le poids et ne comportant pas de racine carrée (ce qui la rend plus facile à utiliser) a été proposée par Costeff et récemment validée pour le groupe d'âge pédiatrique. ${\displaystyle n{\frac {4M+o}{M+p <semantics><mrow><mstyle><mi>n</mi><mrow><mfrac><mrow><mn>4</mn><mi>M</mi><mo>+</mo><mi>o</mi></mrow><mrow><mi>M</mi><mo>+</mo><mi>p</mi></mrow></mfrac></mrow></mstyle></mrow><annotation>{\displaystyle n{\frac {4M+o}{M+p}}}</annotation></semantics></math><img src=$ ${\displaystyle n=1m^{2 <semantics><mrow><mstyle><mi>n</mi><mo>=</mo><mn>1</mn><msup><mi>m</mi><mrow><mn>2</mn></mrow></msup></mstyle></mrow><annotation>{\displaystyle n=1m^{2}}</annotation></semantics></math><img src=$ ${\displaystyle o=7kg <semantics><mrow><mstyle><mi>o</mi><mo>=</mo><mn>7</mn><mi>k</mi><mi>g</mi></mstyle></mrow><annotation>{\displaystyle o=7kg}</annotation></semantics></math><img src=$ ${\displaystyle p=90kg <semantics><mrow><mstyle><mi>p</mi><mo>=</mo><mn>90</mn><mi>k</mi><mi>g</mi></mstyle></mrow><annotation>{\displaystyle p=90kg}</annotation></semantics></math><img src=$

Valeurs moyennes

La surface corporelle moyenne des enfants de différents âges, des hommes et des femmes peut être estimée à l'aide de données d'enquêtes statistiques et d'une formule de surface corporelle :

Les estimations des tableaux ci-dessus sont basées sur les données de poids et de taille de l'enquête nationale américaine NCHS sur la santé et la nutrition (2011-2014).

Il y avait une BSA moyenne de pour 3 000 patients atteints de cancer de 1990 à 1998 dans une base de données de l'Organisation européenne pour la recherche et le traitement du cancer (EORTC).

En 2005, la surface corporelle moyenne (SC) de 3 613 patients adultes atteints de cancer au Royaume-Uni était de les hommes et de les femmes .