Reference Man and Woman More Fully Characterized Variations on the Basis of Body Size, Age, Sex, and Race KENNETH J.
ELUS
USDA/ARS Children's Nutribbn Research Center, Department of Pediatrics, Baylor College of Medicine and the Texas Children's Hospital, Houston, TX 77030 Received June 14, 1989; Accepted November 3, 1989
ABSTRACT Total body neutron activation analysis, prompt-gamma neutron activation analysis, and whole body counting have been used to determine the elemental composition of the human body. The total body elements measured were potassium, nitrogen, calcium, sodium, chlorine, and phosphorus. Total body water was also determined by the dilution principle using tritiated water. Observations were made in an adult US population that totaled 1374 and ranged in age from 20 to 90 yr. The dataset for the white population consisted of 175 males and 1134 females observations; for the black population, it consisted of 30 male and 35 female observations. The variation in the elemental composition of both males and females in any 5-yr age group was large and ranged up to 20% (SD). Age-, race-, sex-, and size-specific differences were evident. When equations were developed that predicted the elemental composition of the adult on the basis of dge, weight, and height, the variation in the age groups was reduced approximately in half. Age-specific mean values for the 20- to 29-yr-old white population were also compared with values for the International Commission on Radiological Protection (ICRP)-23 Reference Man. The "average" young adult male was larger than Reference Man; the in vivo data also indicated a larger skeletal mass, more lean tissues and body water, but lower body sodium. When in vivo Biological Trace Element Research Editor: G. N. Schrauzer 9 1990 by The Humana Press Inc.
385
386
Ellis
prediction equations were used to adjust for size differences, good agreement was found between the expected values and those for Reference Man. The ICRP-23 does not contain elemental data for Reference Woman; therefore, the in vivo data in the present study provide the first estimates of body composition for Reference Woman. Index Entries: Whole-body activation analysis; total body (inorganic composition); body composition; age, sex, and race variations; reference man and woman.
INTRODUCTION A task group of the International Commission on Radiological Protection (ICRP) has developed the concept of a Reference Man (a.k.a. Standard Man) for use in calculating permissible levels of exposure for a typical radiation worker (1). The Reference Man has been defined as one who is 20 to 30 years of age, 70 kg in weight, 170 cm in height, and lives in a climate with an average temperature of 10 to 20~ He is Caucasian and a Western European or North American in habitat and custom. Although the general characteristics of Reference Man were not intended to predict any particular individual or class of individuals, their use has been extended for this purpose in recent years, especially with the resurgent clinical interest in body composition assessment (2--4). Our knowledge of the elemental composition of the human body has increased significantly since the development of in vivo neutron activation analysis. This nuclear analytical technique has enabled a direct quantitative chemical profile of the human body (5). Extensive in vivo measurements of the bulk elements in the body (i.e., calcium, sodium, chlorine, phosphorus, nitrogen, and potassium) have been performed in adults. The values of ICRP-23 Reference Man can now be compared with those from the in vivo observations to provide an indication of the "normal" range of these elements in this population. Total body neutron activation analysis (TBNAA), prompt-gamma neutron activation analysis (PGNAA), and whole body counting (WBC) procedures have been performed on patient populations, with a broad spectrum of metabolic and endocrine disorders in which body composition could be altered. To evaluate the degree of abnormality among the patient populations, it was necessary to establish a normal reference range from observations of a control group of healthy subjects from the general US population. The data collected from the control group have been used to establish the extent of individual variation in body elements among normal subjects, including the effects of age, sex, body size, and race. On the basis of these interrelationships, prediction equations were established for the individual. The in vivo elemental data were compared with values for the ICRP-23 Reference Man. These findings will be used to investigate the concept of a Reference Woman.
Reference Man and Woman
387
METHODS
Subject Populations Body elemental composition measurements were performed over a 15-yr period, from 1972 to 1987. Black and white adult volunteers were recruited from the general US population who lived in the New York CityLong Island, New York metropolitan area. All the subjects were considered physically active for their age and had no prior history or current symptoms of metabolic, renal, or cardiovascular disease at the time of the procedures. Only subjects whose weights were within 25% of that expected for their height and sex were included. Many of the older women were also participants in a prospective study of the incidence of postmenopausal osteoporosis in aging. No subjects received medications known to influence calcium or potassium metabolism. The project was approved by the Human Studies Research Committee at the Brookhaven National Laboratory and an informed consent was obtained from each subject.
Whole Body Counting (WBC) The absolute measurement of total body potassium (TBK) was obtained by counting the natural 4~ content of the whole body. The counter is housed in a shielded room that contains 54 NaI detectors arranged in two 3 x 9 configurations. The counters are positioned above and below the subject. For a 15-min count, the accuracy and precision for measurements of TBK are reported to be +-3.3% using an anthropomorphic adult phantom (6). Reproducibility of the TBK value in a normal healthy adult was found to be +-2.8%.
Total Body Neutron Activation Analysis (TBNAA) The design of the irradiation facility used exclusively for human TBNAA studies has been described previously (7,8). Fourteen 50-Ci 23Spu, Be neutron sources are arranged in two rows above and below the midline of the subject. Fast neutrons are moderated by surrounding the subject with a 3/4 in layer of polyethylene. The exposure time is fixed at 5 min and delivers a total neutron (QF = 10) and gamma dose measured at less than 2.8 mSv (278 torero). The induced activity is measured in the whole body counter for 5 and 15 min, starting 3 min postirradiation. The first 5-min count is optimized for the rapid decay (tl/2 = 2.8 min) of the induced signal from body phosphorus generated by the fast reaction 31p(n,R)28Al. The 15-min spectra contains the Ca, Na, and CI peaks induced by thermal neutron activation. The accuracy and precision for TBNAA, using an anthropomorphic phantom (same model as used for TBK), are reported as *- 1% for total body calcium (TBCa), + 2% for total body chlorine and sodium (TBCI, TBNa), and *-4% for total body phosphorus (TBP) (7,8).
Ellis
388
Prompt-Gamma Neutron Act3ration Analysis (P~t~4a) A detailed description of the facility designed for prompt-gamma neutron activation analysis (PGNAA) has been presented previously (9,10). In vivo measurements are performed using two large volume NaI detectors (6 in dia x 6 in thick) that are positioned above the subject, just out'of the direct view of the neutron beam. An 85-Ci Z38Pu, Be source is located approximately 50 cm below the subject and is shielded to provide a rectangular beam (30 x 60 cm) at the level of the bed. The subject is scanned in prone and supine positions for a total measurement time of 30 min, with a total body dose less than 0.40 mSv (40 mrem). Although most elements in the body emit prompt gammas after thermal neutron capture, body nitrogen and hydrogen are particularly well suited for this type of in vivo analysis. Gamma signals from body chloride, carbon, and calcium are also detectable in the prompt gamma spectra; their precision, however, is less than the TBNAA procedure, and the dosage must be increased significantly. The calculation of total body nitrogen (TBN) is based on an "internal standardization" relative to the body hydrogen gamma signal (9). An independent estimate of body hydrogen is obtained using a tracer dose of tritiated water (30 laCi); the total body dose is less than 0.03 mSv (3 mrem). The HTO is administered orally, and a blood sample is collected 3 to 4 h later. The HTO content of I mL plasma is counted using standard liquid scintillation spectroscopy, and total body water (TBW) is determined by the dilution principle. The precision for TBW has been reported at _+1% in normal healthy adults (11). Reports indicate that a more accurate measurement of body nitrogen is obtained when it is combined with the measurement of body water (10). The precision and accuracy for the in vivo measurement of TBN, using the anthropomorphic phantom, is +3% (9,10). Repeated measurements in a normal healthy adult male over a 6-mo interval showed a _+3.5% variation in the value of TBN.
RESLILTS
Body Composition of the Adult White Population A total of 1309 body composition observations were made in an adult white population. The sampling between the sexes was not uniform, because many of the women also served as controls for clinical protocols involved in the study of osteoporosis. Thus, the number of older females in our sample was larger than younger women or younger and older men. The distribution of males and females is given in Table 1 for each 5-y interval, beginning with age 20. The mean age-slSecific anthropometric values and standard deviations for age, weight, and height are given in Table 1. The body mass index (BMI), defined as weight/height 2,
Reference/Vlan and Woman
389
Table 1 Distribution of Age, Weight, Height, and Body Mass Index (BMI) in an Adult White Population (1134 Females, 175 Males) in the US Age
Group
SubJ ec ts
(.)
Age
Welght
8elgh t
(yr)
(kg)
(m)
BMI*
(kglm 2)
Females 20-24
18
22.1 • 1.4t
59.2 •
6.7
1.62 • .06
22.3 • 1.9
25-29
14
27.3 • 1.4
58.9 •
5.9
1.63 • .06
21.9 • 1.7
30-34
41
32.1 + 1.4
58.2 • 10.9
1.62 • .08
22.1 • 3.8
35-39
53
36.6 • 1.4
62.6 • 10.8
1.63 • .06
23.2 • 3.3
40-44
64
42.4.• 1.3
66.3 • 13.4
1.62 • .06
25.0 • 4.5
45-49
118
47.3 • 1.4
66.2 • 10.2
1.63 • .04
24.7 • 3.4
50-54
243
52.2 • 1.3
68.4 • 12.9
1.63 • .06
25.7 • 4.5
55-59
276
56.8 + 1.4
67.1 • 10.4
1.62 • .05
2 5 . 5 • 3.6
60-64
169
61.6 • 1.4
65.8 • 10.4
1.62 • .06
24.8 • 3.4
65-69
80
66.8 • 1.3
65.5 •
9.2
1.58 • .05
26.0 • 4.1
70-74
58
72.0 • 1.9
61.6 •
6.4
1.58 • .05
24.5 • 2.9
Males 20-24
18
22.4 • 1.4
79.9 • 14.2
1.78 • .04
24.9 z 4.1
25-29
8
27.1 • 1.2
71.7 •
9.3
1.74 • .07
23.3 • 1.7
30-34
20
31.6 • 1.5
72.1 • 11.5
1.74 • .08
23.5 • 2.9
35-39
17
37.4 • 1.4
77.7 •
1.76 • .07
25.0 • 2.6
8.1
40-44
20
41.9 • 1.4
79.9 • 13.8
1.76 • .07
25.6 • 3.8
45-49
20
46.9 • 1.4
76.1 •
9.3
1.75 • .04
24.7 • 2.7
50-54
14
51.8 • 1.4
82.9 • 14.2
1.76 • .07
26.3 • 3.0
55-59
15
56.6 • 1.4
79.1 • 10.9
1.72 • .07
26.6 + 3.2
60-64
15
61.8 • 1.7
80.1 •
1.77 • .04
25.4 • 2.3
9.8
65-69
6
66.3 • 0.8
80.1 • 15.6
1.74 • .03
26.2 • 4.7
70-74
14
72.7 • 2.4
76.6 • 11.2
1.71 •
.06
26.2 • 4.0
75-90
8
85.0 • 4.4
72.5 • I0.7
1.63 • .07
26.9 • 2.4
*BMI (weight/height2). ~Mean +_SD.
390
Ellis
has also been calculated and included in Table 1. FuU stature appeared to have been achieved by age 20-25 for both sexes; the mean values were 1.62 m for females and 1.76 m for males. The mean values for height remained relatively stable through ages 60--64, after which a decrease occurred in the older age groups. As expected, males also weighed more (an average of 14.2 kg) than females at all ages. Mean weights were less stable than mean heights, varying between 59.2 to 68.4 kg in females and 71.7 to 82.9 kg in males. Body weight tended to increase for both sexes through ages 60--64, followed by a moderate loss in the older ages. The trend for body mass index increased throughout life for both sexes. The mean values for BMI ranged from 23 to 27 kg/m 2 for males and 22 to 26 ;g/m 2 for females. Although males had higher BMI values at all ages, the :ate of increase in BMI with age was more rapid in females. The mean values for total body calcium (TBCa), phosphorus (TBP), sodium (TBNa), and chlorine (TBC1) in adult white males and females as a function of age are tabulated in Table 2. The variability in values for eacl~ element in each age group was large; the standard deviations ranged from 8 to 14% for both sexes. The skeleton is the major body compartment represented by TBCa and TBP; :> 98% of body calcium, 85% of body phosphorus are contained in bone. The mean value of TBCa for females is 20-35% lower than the mean for each age group for males. The mean TBCa value for the young male began at 1230 g at 20-24 yr and decreased uniformly to 1096 g by 70--74 yr, a difference of 134 g in 50 yr. When a similar comparison was made among the female groups, a slightly different pattern emerged. The mean TBCa value for ages less than 40 was relatively constant and averaged approximately 900 g, after which a reduction of 175 g occurred over the next 30-35 y. Between the ages of 20 and 70, the mean TBCa value for females decreased significantly in absolute amount and percentage change per year. The difference between the sexes was even more dramatic for ages greater than 45 yr. The body phosphorus pattern was similar to body calcium, although the reduction with age was less because of the higher fraction of body phosphorus in the soft tissues. Total body sodium and chlorine values, however, appeared relatively constant during adult life in healthy individuals. The 175 males had mean values of 83 g sodium and 77.5 g chlorine. The 1134 females had mean values of 63.5 g sodium and 61.5 g chlorine. The results for TBK, TBW, and TBN, obtained by whole body counting, prompt-gamma neutron activation, and tritiated water dilution measurements, respectively, are tabulated in Table 3. The mean values for TBK, TBW, and TBN decreased with increasing age for both males and females. Other investigators have reported similar observations (13,16). The females at ages 70-74 had approximately 11 g less potas.sium, 3 L less water, and 334 g less nitrogen than the 20- to 24-yr-old subjects. The relative effects were a 13% reduction for TBK, a 9% decrease for TBW, and 22% lower TBN levels. The older males also had reduced values for
Reference l~an and Woman
391
Table 2 Total Body Elemental Composition Measured by In Vivo Neutron Activation Analysis in an Adult White Population in the US* Age Group
Calcium
(g)
Phosphorus
TBCa
(g)
TBP
Sodium (g)
Chlorine
TBNa
(g)
TBCI
Females
20-24
905.2
+ 124.0t
439.3
+ 70.4
62.9
~ 7.6
60.1 + 7.0
25-29
905.8
•
78.9
428.3
+ 53.4
62.8
~ 7.6
62.9 + 8.2
30-34
870.3
• 125.4
424.0
• 63.2
62.3
~ 7.8
60.0 + 7.7
35-39
915.7
+ 116.6
433.2 • 59.9
63.8
• 7.2
60.6 + 8.4
40-4~
859.8
+ 108.2
394.1 • 55.2
63.9
• 7.8
61.8 + 7.7
45-49
892.2
+
87.9
412.6 • 51.3
65.4 • 6.3
61.8 + 7.8
50-54
858.8
• 109.8
400.3 • 63.3
65.1
~ 6.8
62.8 + 7.6
55-59
829.0 • 111.8
391.0 • 67.2
63.3 + 6.3
61.3 + 7.3
60-64
799.1 •
99.9
382.1 • 61.9
62.2 • 6.3
61.0 + 8.4
65-69
767.5 f
93.1
374.3 • 59.5
60.3 • 5.5
58.9 + 6.8
70-74
731.1 • 102.1
380.8 + 76.6
59.4 • 5.0
59.6 + 8.0
Males 20-24
1229.8 • 101.1
561.4 + 68.6
84.0 • 7.2
82.1 •
7.9
25-29
1157.0 • 101.5
515.7 • 15.5
79.7 • 5.0
73.1 +
4.6
30-34
1151.1 f 145.0
508.7 + 76.9
81.4 + 9.7
76.6 + 11.6
35-39
1174.5 • 143.9
531.3 • 56.0
84.4 • 9.5
76.7 +
7.6
40-44
1189.5 + 117.1
504.1 + 72.9
85.2 • 9 . 9
74.9 •
9.8
45-49
1107.5
+ 142.3
481.7 • 69.8
81.2
• 5.6
7 5 . 6 +_ 7 . 9
50-54
1144.4 + 108.4
468.2 • 48.9
86.5 • 8.9
78.5 • II.i
55-59
1103.3 _+ 150.9
463.7 _+ 84.8
84.1 + 9.2
76.4 +_ 12.2
60-64
1147.7 + 160.0
492.6 • 95.8
89.2 + 9.7
79.5 + 10.1
65-69
1029.6 :t 122.8
460.8 + 81.8
79.0 • 5 . 4
77.9 +
8.0
70-74
1096,2 i 131.8
538.0 • 64.8
82.5 • 8.1
79.1 +
5.6
75-90
1010.8 + 179.1
466.3 + 62.7
82.6 • 9.7
77.8 +
9.8
* D e l a y e d Neutron 'Mean _+-S D .
Activation Analysis (total
body
dose
ELUS
USDA/ARS Children's Nutribbn Research Center, Department of Pediatrics, Baylor College of Medicine and the Texas Children's Hospital, Houston, TX 77030 Received June 14, 1989; Accepted November 3, 1989
ABSTRACT Total body neutron activation analysis, prompt-gamma neutron activation analysis, and whole body counting have been used to determine the elemental composition of the human body. The total body elements measured were potassium, nitrogen, calcium, sodium, chlorine, and phosphorus. Total body water was also determined by the dilution principle using tritiated water. Observations were made in an adult US population that totaled 1374 and ranged in age from 20 to 90 yr. The dataset for the white population consisted of 175 males and 1134 females observations; for the black population, it consisted of 30 male and 35 female observations. The variation in the elemental composition of both males and females in any 5-yr age group was large and ranged up to 20% (SD). Age-, race-, sex-, and size-specific differences were evident. When equations were developed that predicted the elemental composition of the adult on the basis of dge, weight, and height, the variation in the age groups was reduced approximately in half. Age-specific mean values for the 20- to 29-yr-old white population were also compared with values for the International Commission on Radiological Protection (ICRP)-23 Reference Man. The "average" young adult male was larger than Reference Man; the in vivo data also indicated a larger skeletal mass, more lean tissues and body water, but lower body sodium. When in vivo Biological Trace Element Research Editor: G. N. Schrauzer 9 1990 by The Humana Press Inc.
385
386
Ellis
prediction equations were used to adjust for size differences, good agreement was found between the expected values and those for Reference Man. The ICRP-23 does not contain elemental data for Reference Woman; therefore, the in vivo data in the present study provide the first estimates of body composition for Reference Woman. Index Entries: Whole-body activation analysis; total body (inorganic composition); body composition; age, sex, and race variations; reference man and woman.
INTRODUCTION A task group of the International Commission on Radiological Protection (ICRP) has developed the concept of a Reference Man (a.k.a. Standard Man) for use in calculating permissible levels of exposure for a typical radiation worker (1). The Reference Man has been defined as one who is 20 to 30 years of age, 70 kg in weight, 170 cm in height, and lives in a climate with an average temperature of 10 to 20~ He is Caucasian and a Western European or North American in habitat and custom. Although the general characteristics of Reference Man were not intended to predict any particular individual or class of individuals, their use has been extended for this purpose in recent years, especially with the resurgent clinical interest in body composition assessment (2--4). Our knowledge of the elemental composition of the human body has increased significantly since the development of in vivo neutron activation analysis. This nuclear analytical technique has enabled a direct quantitative chemical profile of the human body (5). Extensive in vivo measurements of the bulk elements in the body (i.e., calcium, sodium, chlorine, phosphorus, nitrogen, and potassium) have been performed in adults. The values of ICRP-23 Reference Man can now be compared with those from the in vivo observations to provide an indication of the "normal" range of these elements in this population. Total body neutron activation analysis (TBNAA), prompt-gamma neutron activation analysis (PGNAA), and whole body counting (WBC) procedures have been performed on patient populations, with a broad spectrum of metabolic and endocrine disorders in which body composition could be altered. To evaluate the degree of abnormality among the patient populations, it was necessary to establish a normal reference range from observations of a control group of healthy subjects from the general US population. The data collected from the control group have been used to establish the extent of individual variation in body elements among normal subjects, including the effects of age, sex, body size, and race. On the basis of these interrelationships, prediction equations were established for the individual. The in vivo elemental data were compared with values for the ICRP-23 Reference Man. These findings will be used to investigate the concept of a Reference Woman.
Reference Man and Woman
387
METHODS
Subject Populations Body elemental composition measurements were performed over a 15-yr period, from 1972 to 1987. Black and white adult volunteers were recruited from the general US population who lived in the New York CityLong Island, New York metropolitan area. All the subjects were considered physically active for their age and had no prior history or current symptoms of metabolic, renal, or cardiovascular disease at the time of the procedures. Only subjects whose weights were within 25% of that expected for their height and sex were included. Many of the older women were also participants in a prospective study of the incidence of postmenopausal osteoporosis in aging. No subjects received medications known to influence calcium or potassium metabolism. The project was approved by the Human Studies Research Committee at the Brookhaven National Laboratory and an informed consent was obtained from each subject.
Whole Body Counting (WBC) The absolute measurement of total body potassium (TBK) was obtained by counting the natural 4~ content of the whole body. The counter is housed in a shielded room that contains 54 NaI detectors arranged in two 3 x 9 configurations. The counters are positioned above and below the subject. For a 15-min count, the accuracy and precision for measurements of TBK are reported to be +-3.3% using an anthropomorphic adult phantom (6). Reproducibility of the TBK value in a normal healthy adult was found to be +-2.8%.
Total Body Neutron Activation Analysis (TBNAA) The design of the irradiation facility used exclusively for human TBNAA studies has been described previously (7,8). Fourteen 50-Ci 23Spu, Be neutron sources are arranged in two rows above and below the midline of the subject. Fast neutrons are moderated by surrounding the subject with a 3/4 in layer of polyethylene. The exposure time is fixed at 5 min and delivers a total neutron (QF = 10) and gamma dose measured at less than 2.8 mSv (278 torero). The induced activity is measured in the whole body counter for 5 and 15 min, starting 3 min postirradiation. The first 5-min count is optimized for the rapid decay (tl/2 = 2.8 min) of the induced signal from body phosphorus generated by the fast reaction 31p(n,R)28Al. The 15-min spectra contains the Ca, Na, and CI peaks induced by thermal neutron activation. The accuracy and precision for TBNAA, using an anthropomorphic phantom (same model as used for TBK), are reported as *- 1% for total body calcium (TBCa), + 2% for total body chlorine and sodium (TBCI, TBNa), and *-4% for total body phosphorus (TBP) (7,8).
Ellis
388
Prompt-Gamma Neutron Act3ration Analysis (P~t~4a) A detailed description of the facility designed for prompt-gamma neutron activation analysis (PGNAA) has been presented previously (9,10). In vivo measurements are performed using two large volume NaI detectors (6 in dia x 6 in thick) that are positioned above the subject, just out'of the direct view of the neutron beam. An 85-Ci Z38Pu, Be source is located approximately 50 cm below the subject and is shielded to provide a rectangular beam (30 x 60 cm) at the level of the bed. The subject is scanned in prone and supine positions for a total measurement time of 30 min, with a total body dose less than 0.40 mSv (40 mrem). Although most elements in the body emit prompt gammas after thermal neutron capture, body nitrogen and hydrogen are particularly well suited for this type of in vivo analysis. Gamma signals from body chloride, carbon, and calcium are also detectable in the prompt gamma spectra; their precision, however, is less than the TBNAA procedure, and the dosage must be increased significantly. The calculation of total body nitrogen (TBN) is based on an "internal standardization" relative to the body hydrogen gamma signal (9). An independent estimate of body hydrogen is obtained using a tracer dose of tritiated water (30 laCi); the total body dose is less than 0.03 mSv (3 mrem). The HTO is administered orally, and a blood sample is collected 3 to 4 h later. The HTO content of I mL plasma is counted using standard liquid scintillation spectroscopy, and total body water (TBW) is determined by the dilution principle. The precision for TBW has been reported at _+1% in normal healthy adults (11). Reports indicate that a more accurate measurement of body nitrogen is obtained when it is combined with the measurement of body water (10). The precision and accuracy for the in vivo measurement of TBN, using the anthropomorphic phantom, is +3% (9,10). Repeated measurements in a normal healthy adult male over a 6-mo interval showed a _+3.5% variation in the value of TBN.
RESLILTS
Body Composition of the Adult White Population A total of 1309 body composition observations were made in an adult white population. The sampling between the sexes was not uniform, because many of the women also served as controls for clinical protocols involved in the study of osteoporosis. Thus, the number of older females in our sample was larger than younger women or younger and older men. The distribution of males and females is given in Table 1 for each 5-y interval, beginning with age 20. The mean age-slSecific anthropometric values and standard deviations for age, weight, and height are given in Table 1. The body mass index (BMI), defined as weight/height 2,
Reference/Vlan and Woman
389
Table 1 Distribution of Age, Weight, Height, and Body Mass Index (BMI) in an Adult White Population (1134 Females, 175 Males) in the US Age
Group
SubJ ec ts
(.)
Age
Welght
8elgh t
(yr)
(kg)
(m)
BMI*
(kglm 2)
Females 20-24
18
22.1 • 1.4t
59.2 •
6.7
1.62 • .06
22.3 • 1.9
25-29
14
27.3 • 1.4
58.9 •
5.9
1.63 • .06
21.9 • 1.7
30-34
41
32.1 + 1.4
58.2 • 10.9
1.62 • .08
22.1 • 3.8
35-39
53
36.6 • 1.4
62.6 • 10.8
1.63 • .06
23.2 • 3.3
40-44
64
42.4.• 1.3
66.3 • 13.4
1.62 • .06
25.0 • 4.5
45-49
118
47.3 • 1.4
66.2 • 10.2
1.63 • .04
24.7 • 3.4
50-54
243
52.2 • 1.3
68.4 • 12.9
1.63 • .06
25.7 • 4.5
55-59
276
56.8 + 1.4
67.1 • 10.4
1.62 • .05
2 5 . 5 • 3.6
60-64
169
61.6 • 1.4
65.8 • 10.4
1.62 • .06
24.8 • 3.4
65-69
80
66.8 • 1.3
65.5 •
9.2
1.58 • .05
26.0 • 4.1
70-74
58
72.0 • 1.9
61.6 •
6.4
1.58 • .05
24.5 • 2.9
Males 20-24
18
22.4 • 1.4
79.9 • 14.2
1.78 • .04
24.9 z 4.1
25-29
8
27.1 • 1.2
71.7 •
9.3
1.74 • .07
23.3 • 1.7
30-34
20
31.6 • 1.5
72.1 • 11.5
1.74 • .08
23.5 • 2.9
35-39
17
37.4 • 1.4
77.7 •
1.76 • .07
25.0 • 2.6
8.1
40-44
20
41.9 • 1.4
79.9 • 13.8
1.76 • .07
25.6 • 3.8
45-49
20
46.9 • 1.4
76.1 •
9.3
1.75 • .04
24.7 • 2.7
50-54
14
51.8 • 1.4
82.9 • 14.2
1.76 • .07
26.3 • 3.0
55-59
15
56.6 • 1.4
79.1 • 10.9
1.72 • .07
26.6 + 3.2
60-64
15
61.8 • 1.7
80.1 •
1.77 • .04
25.4 • 2.3
9.8
65-69
6
66.3 • 0.8
80.1 • 15.6
1.74 • .03
26.2 • 4.7
70-74
14
72.7 • 2.4
76.6 • 11.2
1.71 •
.06
26.2 • 4.0
75-90
8
85.0 • 4.4
72.5 • I0.7
1.63 • .07
26.9 • 2.4
*BMI (weight/height2). ~Mean +_SD.
390
Ellis
has also been calculated and included in Table 1. FuU stature appeared to have been achieved by age 20-25 for both sexes; the mean values were 1.62 m for females and 1.76 m for males. The mean values for height remained relatively stable through ages 60--64, after which a decrease occurred in the older age groups. As expected, males also weighed more (an average of 14.2 kg) than females at all ages. Mean weights were less stable than mean heights, varying between 59.2 to 68.4 kg in females and 71.7 to 82.9 kg in males. Body weight tended to increase for both sexes through ages 60--64, followed by a moderate loss in the older ages. The trend for body mass index increased throughout life for both sexes. The mean values for BMI ranged from 23 to 27 kg/m 2 for males and 22 to 26 ;g/m 2 for females. Although males had higher BMI values at all ages, the :ate of increase in BMI with age was more rapid in females. The mean values for total body calcium (TBCa), phosphorus (TBP), sodium (TBNa), and chlorine (TBC1) in adult white males and females as a function of age are tabulated in Table 2. The variability in values for eacl~ element in each age group was large; the standard deviations ranged from 8 to 14% for both sexes. The skeleton is the major body compartment represented by TBCa and TBP; :> 98% of body calcium, 85% of body phosphorus are contained in bone. The mean value of TBCa for females is 20-35% lower than the mean for each age group for males. The mean TBCa value for the young male began at 1230 g at 20-24 yr and decreased uniformly to 1096 g by 70--74 yr, a difference of 134 g in 50 yr. When a similar comparison was made among the female groups, a slightly different pattern emerged. The mean TBCa value for ages less than 40 was relatively constant and averaged approximately 900 g, after which a reduction of 175 g occurred over the next 30-35 y. Between the ages of 20 and 70, the mean TBCa value for females decreased significantly in absolute amount and percentage change per year. The difference between the sexes was even more dramatic for ages greater than 45 yr. The body phosphorus pattern was similar to body calcium, although the reduction with age was less because of the higher fraction of body phosphorus in the soft tissues. Total body sodium and chlorine values, however, appeared relatively constant during adult life in healthy individuals. The 175 males had mean values of 83 g sodium and 77.5 g chlorine. The 1134 females had mean values of 63.5 g sodium and 61.5 g chlorine. The results for TBK, TBW, and TBN, obtained by whole body counting, prompt-gamma neutron activation, and tritiated water dilution measurements, respectively, are tabulated in Table 3. The mean values for TBK, TBW, and TBN decreased with increasing age for both males and females. Other investigators have reported similar observations (13,16). The females at ages 70-74 had approximately 11 g less potas.sium, 3 L less water, and 334 g less nitrogen than the 20- to 24-yr-old subjects. The relative effects were a 13% reduction for TBK, a 9% decrease for TBW, and 22% lower TBN levels. The older males also had reduced values for
Reference l~an and Woman
391
Table 2 Total Body Elemental Composition Measured by In Vivo Neutron Activation Analysis in an Adult White Population in the US* Age Group
Calcium
(g)
Phosphorus
TBCa
(g)
TBP
Sodium (g)
Chlorine
TBNa
(g)
TBCI
Females
20-24
905.2
+ 124.0t
439.3
+ 70.4
62.9
~ 7.6
60.1 + 7.0
25-29
905.8
•
78.9
428.3
+ 53.4
62.8
~ 7.6
62.9 + 8.2
30-34
870.3
• 125.4
424.0
• 63.2
62.3
~ 7.8
60.0 + 7.7
35-39
915.7
+ 116.6
433.2 • 59.9
63.8
• 7.2
60.6 + 8.4
40-4~
859.8
+ 108.2
394.1 • 55.2
63.9
• 7.8
61.8 + 7.7
45-49
892.2
+
87.9
412.6 • 51.3
65.4 • 6.3
61.8 + 7.8
50-54
858.8
• 109.8
400.3 • 63.3
65.1
~ 6.8
62.8 + 7.6
55-59
829.0 • 111.8
391.0 • 67.2
63.3 + 6.3
61.3 + 7.3
60-64
799.1 •
99.9
382.1 • 61.9
62.2 • 6.3
61.0 + 8.4
65-69
767.5 f
93.1
374.3 • 59.5
60.3 • 5.5
58.9 + 6.8
70-74
731.1 • 102.1
380.8 + 76.6
59.4 • 5.0
59.6 + 8.0
Males 20-24
1229.8 • 101.1
561.4 + 68.6
84.0 • 7.2
82.1 •
7.9
25-29
1157.0 • 101.5
515.7 • 15.5
79.7 • 5.0
73.1 +
4.6
30-34
1151.1 f 145.0
508.7 + 76.9
81.4 + 9.7
76.6 + 11.6
35-39
1174.5 • 143.9
531.3 • 56.0
84.4 • 9.5
76.7 +
7.6
40-44
1189.5 + 117.1
504.1 + 72.9
85.2 • 9 . 9
74.9 •
9.8
45-49
1107.5
+ 142.3
481.7 • 69.8
81.2
• 5.6
7 5 . 6 +_ 7 . 9
50-54
1144.4 + 108.4
468.2 • 48.9
86.5 • 8.9
78.5 • II.i
55-59
1103.3 _+ 150.9
463.7 _+ 84.8
84.1 + 9.2
76.4 +_ 12.2
60-64
1147.7 + 160.0
492.6 • 95.8
89.2 + 9.7
79.5 + 10.1
65-69
1029.6 :t 122.8
460.8 + 81.8
79.0 • 5 . 4
77.9 +
8.0
70-74
1096,2 i 131.8
538.0 • 64.8
82.5 • 8.1
79.1 +
5.6
75-90
1010.8 + 179.1
466.3 + 62.7
82.6 • 9.7
77.8 +
9.8
* D e l a y e d Neutron 'Mean _+-S D .
Activation Analysis (total
body
dose
