Calculation of Heat Production From Insensible Loss of Weight 1

In a previous communication, Newburgh and his associates (1) proposed a method for calcu- lating 24-hour heat production from I. W.2 rather than from I. L.,2 since variations in respiratory quotient cause the relationship of I. W. to I. L. to vary from 85 to 100 per cent.However, in reviewing the literature recently, we were im- pressed with two characteristics of Levine and Marples' (2) prediction curve which they obtained when they plotted I. L. against heat pro- duction in 196 cases.These data were obtained by means of the Russel Sage calorimeter or with the respiration chamber at the New York Nursery and Child's Hospital.The two characteristics were, first, the almost constant percentage of heat removed by vaporization of water throughout the whole course of the line and, second, that the origin of the line is not far from zero.Consequently, we decided to re-examine our own material to determine how closely heat pro- duction can be predicted from I. L. rather than from I. W.The smoothed curve of Levine and Marples is reproduced in Figure 1.We have plotted 34 of our own experiments with 10 normal adults 8 on this diagram.They consist of simultaneous de- terminations of I. L. and heat production for 24- hour periods in the respiration chamber.Further experiments on 11 additional subjects" were also included.Here we have used for the I. L. the average of many consecutive 24-hour periods.The average 24-hour heat production in this series was determined by feeding a carefully weighed constant diet that closely approached maintenance 'The expense of this study was defrayed in part by a grant from the Horace H. and Mary A. Rackham School of Graduate Studies.2 J. W. is an abbreviation for the weight of water vaporized from skin and lungs.I. L. is an abbreviation for the insensible loss of weight.8 These details of the methods and the biological data may be found in earlier publications from this laboratory (1, 3, 4).