ni D arenes , wag oh e fire oA : EUSAPRS, %‘ are 7RE 0ie RST a#t} RS a?A RP . ast aaa 418 - sss PRENTICE, SIRI, BERLIN, HYDE, PARSONS, JOINER, AND LAWRENCE increased from‘ 27 liters/day‘to12.8 Mters/day, e ed ‘turnover innormal’ ea iteeis The difficulties that‘confront effortsto’‘interpret body water metabolism indisease states could doubtless be resolvedif body fat could be deter- mined at the same time. It seems reasonable that if body water can be expressed relative to lean body mass,its significance in disease could be more clearly defined. Although a method now in de- velopment for measuring body fat may be applicable to patients, the existing methods are cither not sufficiently reliable, or they are impractical for use with sick subjects. SUMMARY "1. Total body water has been determined with tritium labeled water in 57 individuals. Twenty were: normal and the remainder were suffering =. es sp ieee one, . A + r a Ne arate a ae ’ . yt t “oem “lo : on . sss, deuterium. 3. The difference betweeri antipyrine and tritium body water volumes is accounted for by exchange of tritium with protein bound hydrogen. 4. Body water determinations vary greatly from individual to individual, the variations in proportion reflecting for the most part variation in body fat. In pathologic states, where the lean body mass cannot be assumed to remain constant in composition, body water determinations are of limited value without a method for quantitating fat. REFERENCES 1. Siri, W.,. Unpublished data. 2. Robinson, C. V.. A methane, proportional counting method for the assay of tritium. Rev. Scient. In- struments, 1951, 22, 353. 3. Mitchell, H. H., Hamilton, T. S, Steggerda, F. R, and Bean, H. W., The chemical composition of the mat IU} 306 Pp NEY eRe : Mat wthAG os, 2. Tritium appears to measure the same water volume as deuterium, averaging 2 to 4% higher than with antipyrine, and undergoes a similar degree of exchange with organic molecules as does ate SRT ee wa. - a aa 2 vat ey : a! ° . . 7 oer oi wt as ets 3 Peas . ; 2 from a variety of disease states. eee capiPea adult human body and its bearing on the biochem- istry of growth. J. Biol. Chem, 1945, 158, 625. , the biologicalhalf-tife.wasFe duced:Lac10days. "4, Lavietes; P.H., D’Esopo, L. M., and Harrison, H. E., “to 2.5 days,ill “The water and base balanceof the body. J. Cin. Invest, 1935, 14, 251. 5, Rathbun, E., and Pace, N., Studies on body composition. I. Determination of total body fat by means of the body specific gravity. J. Biol. Chem., 1945, 158, 667. 6. Osserman, E. F., Pitts, G. C, Welham, W. C., and Behnke, A. R., In vivo measurement of body fat and body water ina group of normal men. J. Appl. Physiol., 1950, 2, 633. 7. Levitt, M. F., and Gaudino, M., Measurements of body water compartments. Am. J. Med, 1950, 9, 208. 8 DaCosta, E., and Clayton, R, Report of the fat and water content and the specific gravity of the total carcass of the albino rat in relation to dietary re- striction and rehabilitation. U.S. Army Medical Nutrition Laboratory, Chicago, Report No. 62, Sept, 1949. 9. Morales, M. F., Rathbun, E. N., Smith, R. E,, and Pace, N., Studies on body composition. II. Theoretical considerations regarding major body tissue components with suggestions for application to man. J. Biol. Chem., 1945, 158, 677. 10. Pace, N., Kline, L., Schachman, H. K., and Harfenist, M., Studies on body composition. IV. Use of ra- dioactive hydrogen for measurement in vivo of total body water. J. Biol. Chem., 1947, 168, 459. ‘Ll. Schloerb, P. R. Friis-Hansen, B. J., Edelman, I. S., Solomon, A. K., and Moore, F. D., The measure- ment of total body water in the human subject by deuterium oxide dilution. J. Clin. Invest. 1950, 29, 1296. 12. Pinson, E. A., and Anderson, E. C., The body ab- sorption, distribution and excretion of tritium in man and animals. sion. The Atomic Energy Commis- Report LA-1218, March 12, 1951. 13. Brodie, B. B., Axelrod, J.. Soberman, R., and Levy, B. B., The estimation of antipyrine in biological materials. J, Biol. Chem. 1949, 179, 25. 14. Soberman, R., Brodie, B. B., Levy, B. B., Axelrod, J., Hallander, V., and Steele, J. M., The use of anti- pyrine in the measurementof total body water in man. J. Biol. Chem. 1949, 179, 31. 1S. Pace, N., Unpublished data. 16. Ussing, H. H., The exchange of H and D atoms between water and protein is vivo and im vitro. Skandinayv. Arch. f. Physiol. 1938, 78, 225. 17. Steele, J. M., Berger, E. Y., Dunning, M. F., and Brodie, B. B., Total body water in man. Am. J. Physiol., 1950, 162, 313.