416 PRENTICE}! BIRE;“BERLIN, WYDE; PARSONS, JOINER, AND LAWRENCE 7 3 2 TaN: PRIVACY ACT MATERIAL REMOVED bean, betes Ege? A Ve°TABLE IV D ? mo | Petlent 9 getektogdapsonewtoht wanfaders ews Mu 47 20 38 Mean ics : op Moe FF oF Diagnose - TE Gey P+ Ob. 1, 60.8 + sais 49.8 $7.8 “28.0 43.0 |. 610 H-CVv.D. (61.0 H.C.V.D, with uremia 629.6. fo 49.0 29.8 |” 546 32.6 | ASH.D. H.C.V.D. S64 {st 5.8 B. With peripheral edema 48 FO 71 62 74 | “ $9.6 73.4 F “T8.5 61. FG]: 69.4; “4. | F 47 Mean “468 M mM 40%: 55.5: M: FC ‘ ry | - 26:5 $6.6 27.6| 35.2 340. 49.0, * §3.2": 65.0 - ' 33.6° 44.0 70.0%. , 417 63.7 - 3M $6.75 $3.51 36.9 : 564 60.0 59.$ 66.5 $6.0 ° Rheum. he, disease [AS.H:D. H.C.V.D. H.GV.D.(very obese; little . Rh. ht. disease |H.CV.D. {|H.CV.D 210.6 C With pulmonarycongestion but no peripheral edema $9 74 uM 53 Mean F M F F $5 82.0 -102.3 $1.7 614 74.4 M4 35.4 35,2 © 27.5 42.0 44.6 68.0 4.8 33.1 47.4 A.S.H.D. Emphysema M ial infarct. | H.CN.D, H.C.V.D. 14.3 Pace, Kline, Schachman, and Harfenist (10)* and 0.27 is the fraction of solids in wet tissue. The carcass weight was taken as 56.5% after subtracting bone minerals. Inserting these values in the formula above,the total body water one would ex- pect to observe with tritium is then approximately 74.5% of the lean body mass. The correction .factor representing the maximum error, f.¢., for a lean subject, is 0.73/0.745 = 0.98. The difference of about 2% correspondsclosely with the average of 2.3% in the differences in body water volumes observed when antipyrine is compared with tritium, as may be seen in Table II. This correction is not made in Tables II-V, because its exact value de® The value used here is derived from Pace's figures for the nitrogen content of dry, fatfree tissue. 3012068 pends upon a more exact determination of lean tissue mass in individual cases. Twofacts are worthy of note. First, the magnitude of the error is not changed by the degree of obesity; and second, in edematous states, the er- ror decreases as edema increases. The first is true because adipose tissue does not alter significantly either the amount of exchangeable hydrogen atoms or the volume of body water. The secondis evi- dent because as body water increases, the amount of tritium exchanged remains the same. DISCUSSION Radiation dosage is always an important consideration in the utilization of radioactive tracers. Two me. of T,O were selected for use in these PRIVACY ACT MATERIAL REMOVED