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Total body oxygen: Assessment from body weight and total body water
Appl. Radiat. lsot. Vol. 49, No. 5/6, pp. 603-605. 1998
Pergamon P l h S0969-8043(97)00080-8
© 1998 ElsevierScience Ltd. All rights reserved Printed in Great Britain 0969-8043/98 $19.00+ 0.00
Total Body Oxygen: Assessment from Body Weight and Total Body Water Z I - M I A N W A N G I, P A U L D E U R E N B E R G 2, R U I M E I M A 3, D O N A L D K O T L E R ~ a n d S T E V E N B. H E Y M S F I E L D ~ ~St. Luke's-Roosevelt Hospital, Columbia University, New York, NY, U.S.A., 2Department of Human Nutrition, Wageningen Agricultural University, Wageningen, The Netherlands and 3Medical Department, Brookhaven National Laboratory, Upton, New York, NY, U.S.A.
Introduction
Methods
Oxygen is the most abundant element in the human body which, for example, accounts for 61% of body weight in the Reference Man. Measurement of total body oxygen (TBO) and its change with age, race, sex, nutrition, and disease might be useful in understanding human body composition. At present, the methods for measuring TBO, which require in t, ivo neutron activation (NA), are expensive and involve radiation (Kehayias and Zhang, 1993; Mitra et al., 1995). The purpose of the present study was to derive and evaluate a TBO model from total body water (TBW) and body weight (BW). As an initial phase, we developed an equation relating TBO with components at the molecular level. The chemical stoichiometries are C55Ht0206 for fat, H20 for water, C~00H~59N2eO32So7 for protein (Pro), (C6HLoOs), for glycogen (G), and [Ca3(PO4)z]3Ca(OH)2 for calcium hydroxyapatite, the main compound of bone mineral (Mo) (Heymsfield et al., 1991). The proportions of the components as oxygen are: 11.3% of fat, 88.9% of water, 22.7% of Pro, 49.4% of G, and 41.4% of Mo. Hence, a TBO equation is derived:
The subject pool consisted of 19 healthy adult males and 18 men with AIDS. All subjects signed an informed consent that was approved by the hospital's Institutional Review Board. BW was obtained to the nearest 0.1 kg. TBW was measured by tritium dilution (TBW = 3H20 × 0.96 × 0.994) at St. Luke's with a precision of 1.7% (CV) (Ma et al., 1996). The total body content (TB) of seven elements was quantified using the in vivo N A facility at the Brookhaven National Laboratory. TBC was measured using inelastic neutron scattering with a CV of 11.0%. TBCa, TBP, TBNa, and TBCI were measured using delayed-7 N A with CVs of 1.6%, 4.5%, 1.8%, and 1.2%, respectively. TBN and TBH were determined by prompt-y N A with a CV of 1.8% (Ma et al., 1996). TBK was determined using St. Luke's 4x whole body counter with a CV of 3.2%. TBO was calculated as the difference between 99.3% of BW and the sum of the eight elements: TBO = 0.993 × BW - E(C,H,N,Ca,P,K,Na,C1). In the equation the coefficient 0.993 is based on the consideration that sulfur and other trace elements account for 0.7% of BW in the Reference Man.
TBO = 0 . 1 1 3 x fat + 0.889 x TBW + 0.227 x Pro + 0.494 x G + 0.414 x Mo.
Results The TBO for the pooled subjects estimated by the model (mean _+ SD, TBOu = 44.9 _+ 7.4 kg) agreed within 0.2% with the TBO measured by N A (TBONA = 45.0 _ 7.5 kg; Student t-test, p > 0.05) (Table 1). The two measures of TBO were highly correlated:
Whole body in vitro chemical analysis of six cadavers revealed that the proportions of F F M as water, protein and mineral are relatively constant at 0.724 + 0.034, 0.205 _+ 0.028, and 0.071 _+ 0.013, respectively (Garrow, 1993). G accounts for ~ 1% of F F M . Thus the TBO equation can be simplified as:
TBOM = 0.938 x TBONA + 3.0, r = 0.98, p < 0.001, n = 19 healthy males;
TBO = 0.113 x BW + 0.845 x TBW.
TBOu = 0.925 x TBONA + 2.9, r = 0.94, p < 0.001, n = 18 males with AIDS.
The present study was designed to evaluate the proposed TBO prediction model.
Because the slopes and intercepts of the two equations did not differ (p > 0.05), the data for the 603
Zi-Mian Wang et al.
604
Table 1. Results of body composition studies Healthy males (n = 19) Mean Age (year) BW (kg) Ht (m) BMI (kg/m2) TBC (kg) TBH (kg) TBN (kg) TBC (kg) TBP (kg) TBK (kg) TBNa (kg) TBCI (kg) TBW (kg) TBOsA (kg) TBOM (kg)
SD
36.7 76.6 1.76 24.5 16.2 7.7 2.07 0.954 0.573 0.164 0.085 0.089 47.0 48.2 48.2
13.2 13.3 0.08 2.9 4.0 1.4 0.24 0.139 0,08 l 0.031 0.010 0.012 7.4 8.l 7.7
two groups were combined (Fig. 1: O, healthy males; O, males with AIDS): TBOu = 0.956 x TBONA + 1.9, r = 0.98, p < 0.001, SEE = 1.6 kg, n = 37.
Male AIDS (n = 18) Range
Mean
19 72 55.8-104.5 1.62-1.93 20.1-30.5 9.5 24.2 5.5-10.7 1.68 2.53 0.708-1.289 0.452~?.727 0.105-0.219 0.068M). 110 0.072-0.125 34.5-59.4 37.0-64.5 35.~61.8
38.9 64.0 1.73 21.3 12.1 6.4 1.70 0.839 0.523 0.127 0.078 0.084 40.6 41.7 41.4
0.11 + -0.16 -0.02 results model.
Agreement between TBOM and TBONA was evaluated using the analysis of Bland and Altman (Fig. 2). The mean difference in the two methods was
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TBO (neutron activation) (kg) Fig. 1. Total body oxygen (TBO) estimated by the model vs total body oxygen measured by neutron activation. 8 -6 --
4-
Range 22-62 48.5 77.1 1.57 1.82 17.0-26.0 6.8-21.5 4.9 7.9 1.33-2.13 0.62 1.057 0.3494?.64 0.085~). 158 0.0584).101 0.06447.109 32.6-50.4 31.5 50.0 33.0-50.1
0.34 kg for the healthy males, ± 0.54 kg for the males with AIDS, and ± 0.46 kg for the combined groups. These confirm the adequacy of the proposed TBO
Discussion The TBO calculated from the model was confirmed by TBO using in vivo N A as reference, both in healthy males and in males with AIDS. This indicated that, although A I D S is a wasting disease, it had no influence on the validity of the proposed model. The proposed method has two main error sources, water measurement error and model error. TBW is measured with a CV of 1.7%. For the Reference Man of 42 kg TBW, the water measurement error is 0.60 kg of oxygen. The model error is mainly concerned with the assumption that the proportions of F F M as water, protein, and mineral are constant. It is known that these proportions vary somewhat within and between individuals. For the Reference Man, the model error is 2.13 kg of oxygen. The total error of the TBO model is thus 2.2 kg for the Reference Man with 43 kg oxygen. Comparatively, the TBO measurement error in N A method is small (1.54 kg). However, the N A method cannot be widely applied, because of the high cost and radiation exposure. As the TBW dilution method is widely available, the proposed model potentially provides a simple, low cost, and safe method of assessing TBO in vivo.
v t-
SD 10.3 7.9 0.07 2.3 3.7 0.8 0.21 0.101 0.074 0.018 0.010 0.011 5.3 5.3 5.2
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Fig. 2. The difference between the two methodsin Fig, 1 as a function of the mean value of total body oxygen.
Garrow, J. S. (1993) Composition of the body. In Human Nutrition and Dietetics, eds J. S. Garrow and W. P T. James, 9th edn, pp. 12-25. Churchill Livingstone. Heymsfield, S. B., Waki, M., Kehayias, J., Lichtman, S., Dilmanian, F. A., Kamen, Y., Wang, J. and Pierson, R. N. Jr. (1991) Chemical and elemental analysis of humans in vivo using improved body composition models. Am. J. Physiol. 261, El90. Kehayias, J. J. and Zhang, H. (1993) Measurement of regional body fat in vivo in humans by simultaneous detection of regional carbon and oxygen, using neutron
Total body oxygen: assessment from body weight and total body water inelastic scattering at low radiation exposure. In Human Body Composition, In Vivo Methods, Models, and Assessment, eds K. J. Ellis and J. D. Eastman, pp. 49-52. Plenum Press, New York. Ma, K., Kotler, D. P., Wang, J., Thornton, J. C., Ma, R. and ,Pierson R. N. Jr. (1996) Reliability of in vivo neutron activation analysis for measuring body composition:
605
Comparison with trace dilution and dual-energy X-ray absorptiometry. J. Lab. Clin. Med. 127, 420. Mitra, S., Wolff, J. E., Garrett, R. and Peters, C. W. 0995) Application of the associated particle technique for the whole-body measurement of protein, fat and water by 14 MeV neutron activation analysis--a feasibility study. Phys. Med. Biol. 40, 1045.
Pergamon P l h S0969-8043(97)00080-8
© 1998 ElsevierScience Ltd. All rights reserved Printed in Great Britain 0969-8043/98 $19.00+ 0.00
Total Body Oxygen: Assessment from Body Weight and Total Body Water Z I - M I A N W A N G I, P A U L D E U R E N B E R G 2, R U I M E I M A 3, D O N A L D K O T L E R ~ a n d S T E V E N B. H E Y M S F I E L D ~ ~St. Luke's-Roosevelt Hospital, Columbia University, New York, NY, U.S.A., 2Department of Human Nutrition, Wageningen Agricultural University, Wageningen, The Netherlands and 3Medical Department, Brookhaven National Laboratory, Upton, New York, NY, U.S.A.
Introduction
Methods
Oxygen is the most abundant element in the human body which, for example, accounts for 61% of body weight in the Reference Man. Measurement of total body oxygen (TBO) and its change with age, race, sex, nutrition, and disease might be useful in understanding human body composition. At present, the methods for measuring TBO, which require in t, ivo neutron activation (NA), are expensive and involve radiation (Kehayias and Zhang, 1993; Mitra et al., 1995). The purpose of the present study was to derive and evaluate a TBO model from total body water (TBW) and body weight (BW). As an initial phase, we developed an equation relating TBO with components at the molecular level. The chemical stoichiometries are C55Ht0206 for fat, H20 for water, C~00H~59N2eO32So7 for protein (Pro), (C6HLoOs), for glycogen (G), and [Ca3(PO4)z]3Ca(OH)2 for calcium hydroxyapatite, the main compound of bone mineral (Mo) (Heymsfield et al., 1991). The proportions of the components as oxygen are: 11.3% of fat, 88.9% of water, 22.7% of Pro, 49.4% of G, and 41.4% of Mo. Hence, a TBO equation is derived:
The subject pool consisted of 19 healthy adult males and 18 men with AIDS. All subjects signed an informed consent that was approved by the hospital's Institutional Review Board. BW was obtained to the nearest 0.1 kg. TBW was measured by tritium dilution (TBW = 3H20 × 0.96 × 0.994) at St. Luke's with a precision of 1.7% (CV) (Ma et al., 1996). The total body content (TB) of seven elements was quantified using the in vivo N A facility at the Brookhaven National Laboratory. TBC was measured using inelastic neutron scattering with a CV of 11.0%. TBCa, TBP, TBNa, and TBCI were measured using delayed-7 N A with CVs of 1.6%, 4.5%, 1.8%, and 1.2%, respectively. TBN and TBH were determined by prompt-y N A with a CV of 1.8% (Ma et al., 1996). TBK was determined using St. Luke's 4x whole body counter with a CV of 3.2%. TBO was calculated as the difference between 99.3% of BW and the sum of the eight elements: TBO = 0.993 × BW - E(C,H,N,Ca,P,K,Na,C1). In the equation the coefficient 0.993 is based on the consideration that sulfur and other trace elements account for 0.7% of BW in the Reference Man.
TBO = 0 . 1 1 3 x fat + 0.889 x TBW + 0.227 x Pro + 0.494 x G + 0.414 x Mo.
Results The TBO for the pooled subjects estimated by the model (mean _+ SD, TBOu = 44.9 _+ 7.4 kg) agreed within 0.2% with the TBO measured by N A (TBONA = 45.0 _ 7.5 kg; Student t-test, p > 0.05) (Table 1). The two measures of TBO were highly correlated:
Whole body in vitro chemical analysis of six cadavers revealed that the proportions of F F M as water, protein and mineral are relatively constant at 0.724 + 0.034, 0.205 _+ 0.028, and 0.071 _+ 0.013, respectively (Garrow, 1993). G accounts for ~ 1% of F F M . Thus the TBO equation can be simplified as:
TBOM = 0.938 x TBONA + 3.0, r = 0.98, p < 0.001, n = 19 healthy males;
TBO = 0.113 x BW + 0.845 x TBW.
TBOu = 0.925 x TBONA + 2.9, r = 0.94, p < 0.001, n = 18 males with AIDS.
The present study was designed to evaluate the proposed TBO prediction model.
Because the slopes and intercepts of the two equations did not differ (p > 0.05), the data for the 603
Zi-Mian Wang et al.
604
Table 1. Results of body composition studies Healthy males (n = 19) Mean Age (year) BW (kg) Ht (m) BMI (kg/m2) TBC (kg) TBH (kg) TBN (kg) TBC (kg) TBP (kg) TBK (kg) TBNa (kg) TBCI (kg) TBW (kg) TBOsA (kg) TBOM (kg)
SD
36.7 76.6 1.76 24.5 16.2 7.7 2.07 0.954 0.573 0.164 0.085 0.089 47.0 48.2 48.2
13.2 13.3 0.08 2.9 4.0 1.4 0.24 0.139 0,08 l 0.031 0.010 0.012 7.4 8.l 7.7
two groups were combined (Fig. 1: O, healthy males; O, males with AIDS): TBOu = 0.956 x TBONA + 1.9, r = 0.98, p < 0.001, SEE = 1.6 kg, n = 37.
Male AIDS (n = 18) Range
Mean
19 72 55.8-104.5 1.62-1.93 20.1-30.5 9.5 24.2 5.5-10.7 1.68 2.53 0.708-1.289 0.452~?.727 0.105-0.219 0.068M). 110 0.072-0.125 34.5-59.4 37.0-64.5 35.~61.8
38.9 64.0 1.73 21.3 12.1 6.4 1.70 0.839 0.523 0.127 0.078 0.084 40.6 41.7 41.4
0.11 + -0.16 -0.02 results model.
Agreement between TBOM and TBONA was evaluated using the analysis of Bland and Altman (Fig. 2). The mean difference in the two methods was
65 --
/.
f"
60 -"~ 55
"U 50 o
E ©
45
--
°
301/"
I
I
I
I
I
I
I
30
35
40
45
50
55
60
65
TBO (neutron activation) (kg) Fig. 1. Total body oxygen (TBO) estimated by the model vs total body oxygen measured by neutron activation. 8 -6 --
4-
Range 22-62 48.5 77.1 1.57 1.82 17.0-26.0 6.8-21.5 4.9 7.9 1.33-2.13 0.62 1.057 0.3494?.64 0.085~). 158 0.0584).101 0.06447.109 32.6-50.4 31.5 50.0 33.0-50.1
0.34 kg for the healthy males, ± 0.54 kg for the males with AIDS, and ± 0.46 kg for the combined groups. These confirm the adequacy of the proposed TBO
Discussion The TBO calculated from the model was confirmed by TBO using in vivo N A as reference, both in healthy males and in males with AIDS. This indicated that, although A I D S is a wasting disease, it had no influence on the validity of the proposed model. The proposed method has two main error sources, water measurement error and model error. TBW is measured with a CV of 1.7%. For the Reference Man of 42 kg TBW, the water measurement error is 0.60 kg of oxygen. The model error is mainly concerned with the assumption that the proportions of F F M as water, protein, and mineral are constant. It is known that these proportions vary somewhat within and between individuals. For the Reference Man, the model error is 2.13 kg of oxygen. The total error of the TBO model is thus 2.2 kg for the Reference Man with 43 kg oxygen. Comparatively, the TBO measurement error in N A method is small (1.54 kg). However, the N A method cannot be widely applied, because of the high cost and radiation exposure. As the TBW dilution method is widely available, the proposed model potentially provides a simple, low cost, and safe method of assessing TBO in vivo.
v t-
SD 10.3 7.9 0.07 2.3 3.7 0.8 0.21 0.101 0.074 0.018 0.010 0.011 5.3 5.3 5.2
z-
•
•o
c~
.o 0 - -
o•o
• •
o
•
References
o
(2) --
o o
o ~. (4) --
•
o
o o
•
(6) -(8)
30
I 35
I 40
I J I 45 50 55 Mean TBO (kg)
I 60
65
Fig. 2. The difference between the two methodsin Fig, 1 as a function of the mean value of total body oxygen.
Garrow, J. S. (1993) Composition of the body. In Human Nutrition and Dietetics, eds J. S. Garrow and W. P T. James, 9th edn, pp. 12-25. Churchill Livingstone. Heymsfield, S. B., Waki, M., Kehayias, J., Lichtman, S., Dilmanian, F. A., Kamen, Y., Wang, J. and Pierson, R. N. Jr. (1991) Chemical and elemental analysis of humans in vivo using improved body composition models. Am. J. Physiol. 261, El90. Kehayias, J. J. and Zhang, H. (1993) Measurement of regional body fat in vivo in humans by simultaneous detection of regional carbon and oxygen, using neutron
Total body oxygen: assessment from body weight and total body water inelastic scattering at low radiation exposure. In Human Body Composition, In Vivo Methods, Models, and Assessment, eds K. J. Ellis and J. D. Eastman, pp. 49-52. Plenum Press, New York. Ma, K., Kotler, D. P., Wang, J., Thornton, J. C., Ma, R. and ,Pierson R. N. Jr. (1996) Reliability of in vivo neutron activation analysis for measuring body composition:
605
Comparison with trace dilution and dual-energy X-ray absorptiometry. J. Lab. Clin. Med. 127, 420. Mitra, S., Wolff, J. E., Garrett, R. and Peters, C. W. 0995) Application of the associated particle technique for the whole-body measurement of protein, fat and water by 14 MeV neutron activation analysis--a feasibility study. Phys. Med. Biol. 40, 1045.