1) DuBois D,DuBois DF. A formula to estimate the approximate surface area if height andweight be known. Arch Int Med 1916;17:863-71.
Equation: BSA (m2) = 0.007184 x Height(cm)0.725 xWeight(kg)0.425
2) GehanEA, George SL. Estimation of human body surface area from height and weight.Cancer Chemother Rep 1970;54:225-35.
Equation: BSA (m2) = 0.0235 x Height(cm)0.42246 xWeight(kg)0.51456
3) Hayco*ck GB, Schwartz GJ, Wisotsky DH. Geometric method for measuring body surface area:A height-weight formula validated in infants, children and adults. JPediatr 1978;93:62-6.
Equation: BSA (m2) = 0.024265 x Height(cm)0.3964 xWeight(kg)0.5378
4) MostellerRD. Simplified calculation of body-surface area. N Engl J Med 1987;317:1098.
Equation: BSA (m2) = SQR RT ( [Height(cm) xWeight(kg) ]/ 3600 )
What is Body Surface Area?
The measured surface area of the body is termed as the Body Surface area or BSAin physiology and medicine. Its normal value is considered to be 1.7m². Thisparameter shows the metabolic mass rather than the body weight for clinicalpurposes. This is because the unusual body adipose mass doesn't affect it. Thereare numerous judgments related to BSA's use in the determination of medicinedosage with a narrow therapeutic index, like chemotherapy, pharmacotherapy, etc.
BSA determination is essential for the dosages of some drugs thatneed to be administered to a patient. It is also used in some cases to determinefluid requirements administeredintravenously. There were many formulas developed in the past years forcalculating the Body Surface Area. The Mosteller formula is considered to be the most common bodysurface area equation today. The New England Journal of Medicine published itin the year 1987.
Different genetic and environmental factors affect the drug elimination processin various individuals. Further, there are 4-10 fold variations possible. This resultsin notable overdosing or underdosing, which also significantly increases thechances of recurrence of the disease.
It is considered to be a distorting factor in Phase I and II trials, resultingin the premature rejection of many helpful medications. The efficient method ofdealing with this variability is paramount.
What are classifications of Body Surface Area?:
Height and weight are not the only determinants of BSA. Age and gender are theother prime factors. Here are the classifications:
1. For adult men, the average BSA is 1.9 m².
2. It is 1.6 m² for adult women.
3. In the case of newborn kids, it is 0.25 m²; for those of 2 years age, it is0.5 m²; 10-year old kids average 1.14 m², and for those of 12-13 years of age, it is 1.33m².
What is the difference between Body Mass Index (BMI) and Body SurfaceArea(BSA)?:
Both these parameters have frequent usage in the healthcare sector butare oftenconfused. Each of them provides us different information. First, let us considerBody Mass Index (BMI) which is beneficial in determining how overweight a personis. This reliable parameter is used for easily correlating it with the body fatmass percentage. BMI accurately estimates the total fat rather than body weight.Thus it helps in assessing the risk factors such as heart disease, high bloodpressure, gallstones, respiratory issues, some kinds of cancer and type 2diabetes.
The only drawback of BMI is that it overestimates the fat in the case ofathletes as well as those with a muscular build. Even in the case of elderlypeople and those who have muscle atropy, it can underestimate body fat. In orderto calculate the BMI, we take the bodyweight of the person in kilograms anddivide it by height squared, as mentioned below:
BMI= Weight/ Height0.5
Depending on the cardiovascular risk, BMI is categorized for the differentraces, such as African-American race, Caucasian and Hispanic. But if we considerthe case of Asians and South East Asians, the parameter underestimates theobesity risk because of which a lower threshold has to be used in such cases.
According to the NIH, the waist measurement along with the BMI in obeseand overweight adults is needed for abdominal obesity assessment. For example,when the waist circumference exceeds 40 inches in men and 35 inches in women,the risk of cardiovascular and metabolic disorders increases.
Now let us consider the BSA. As opposed to the BMI, BSA measures the total bodysurface area for drug doses estimation or medical assessments. Du Bois developedthe first formula in the year 1916 after which many formulas were developed tomeasure it. Among all of them, the Mostella formula is the easiest one formemorizing as well as calculating and is therefore used in clinical trials.
