Body surface area is increasingly used as a dosage criterion, not only for administration of water and electrolytes,1,2 but also for drug therapy.3 Its chief merit is that requirements for water and electrolytes, as well as therapeutic doses of many pharmaceutical agents, are roughly proportional to body surface area, except for neonates and premature infants. The convenience thus offered the clinician is obvious. In addition, body surface area appears to offer increased accuracy and safety, despite theoretical objections4 to its scientific validity as a gauge for dosage.
The physician cannot, of course, measure body surface area directly. For this reason, nomograms (requiring measurement of height and weight) and weight-to-surface area tables (requiring weight only) have been employed. But the physician who forgets his nomogram or table, or who has no way to obtain the patient's weight, cannot estimate the patient's body surface area. A less cumbersome method
Snively WD, Montenegro JLB, Dick RG. Quick Method for Estimating Body Surface Area. JAMA. 1966;197(3):208-209. doi:10.1001/jama.1966.03110030102034