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29 Accuracy, reproducibility and normal total body potassium (TBK) ranges measured using the renovated
whole body 40K counter of St Luke’s-Roosevelt Hospital
Benjamin Schneider, Jack Wang, John C. Thornton, John Arbo, Mary Horlick, Steven B. Heymsfield and
Richard N. Pierson, Jr.
30 Monte Carlo modeling – an essential tool in whole-body counter design
R.J. Shypailo and K.J. Ellis
31 The prediction of fat-free mass from bioelectrical impedance analysis in children and adolescents with
cystic fibrosis
A.J. Murphy, H.M. Buntain and P.S.W. Davies
32 Validity of skinfolds in comparison to DXA for estimating adiposity in Aboriginal Australian women
C. Raja1, R. Hansen2, S. Colagiuri3 and B.J. Allen
33 Changes in body composition during upper gastrointestinal cancer surgery
A. Aslani, B.A. Cooper, A. Sevette and R.C. Smith
34 In-vivo body composition measurements in cancer and surgery
Alireza Aslani and Ross C. Smith
International Journal of Body Composition Research 2004, Vol. 2 No. 2: 51-60
Benjamin Schneider, Jack Wang, John C. Thornton, John Arbo, Mary Horlick, Steven B. Heymsfield and
Richard N. Pierson, Jr.
Body Composition Unit, Department of Medicine, St Luke’s-Roosevelt Hospital Center, Columbia University
College of Physicians and Surgeons, New York, USA.
Whole body 40K counting is a reliable and non-invasive method for measurement of the body cell mass, a parameter of body composition, which is of central importance in studies of nutritional physiology. The 4p liquid scintillation 40K counter at St Luke’s-Roosevelt Body Composition Unit was installed in 1967 and was renovated and recalibrated in 1994. This study reports the counting efficiency, accuracy, and reproducibility of the current system, and presents normal TBK ranges in healthy subjects. Counting efficiency was measured using 19 calibration standards (30 to 210 lb) with known potassium content, accuracy was measured using 14 phantoms with known potassium content (41–206 lb), and reproducibility was measured by repeat counting of 12 human subjects (37 to 205 lb). The renovated 4p liquid scintillation system provided improvements in efficiency, accuracy, and reproducibility, and extended the range in which body potassium can be measured down to 40 lb, r = 0.998 by intraclass correlation and mean CV of 2.3%, a marked improvement for human body composition studies. TBK data in healthy volunteers (n=1367; 676 females and 700 males, ages 3–90 years) are presented to show normal TBK ranges. The TBK in males peaked at age 27.5, 4500 mEq, and decreased to 2250 mEq by age 80 years (a decrease of 430 mEq per decade). For females, the TBK peaked at age 22, at 2450, and decreased to 1700 mEq at age 80 (a decrease of 130 mEq per decade).
International Journal of Body Composition Research 2004, Vol. 2 No. 2: 61-67
R.J. Shypailo and K.J. Ellis
USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine,
Houston, TX 77030, USA
The re-building of the Children’s Nutrition Research Center whole- body counter (WBC) required system construction without a low-background shielded room. Weight and size limitations necessitated development of shielded detectors rather than a shielded room. Modeling various detector and shield arrangements allowed us to evaluate a greater number of system designs than could be efficiently measured empirically. A Monte Carlo simulation program (MCNP-4B2; Los Alamos National Laboratory) was used to examine several WBC designs. The 40K gamma peak region was assessed in simulations representing background and subject sources. Three evaluation types were performed: (1) optimal shielding thickness, (2) counter design assessment, including detector placement and counter shape, and (3) empirical testing, including background surveys and tests of relative detector positioning. MCNP performed well in predicting relative system response. Optimal shield thickness for 40K counting was determined to be 7–8 cm of lead or equivalent. An enclosed (cylindrical) counter design was found to be necessary to achieve system precision of 1.5% or better. It is concluded that weight and size limitations influence the design considerations in developing a whole-body gamma counter. These constraints require advanced system testing that could not have been completed without the use of Monte Carlo modeling tools. The counter design chosen should perform at a precision of less than 1.5% for a total body potassium counting time of 15 minutes, and have a weight of less than 8200 kg with a footprint of 1.2 m x 2.4 m.
International Journal of Body Composition Research 2004, Vol. 2 No. 2: 69-74
A.J. Murphy1, H.M. Buntain2 and P.S.W. Davies1
1Children’s Nutrition Research Centre, Department of Paediatrics and Child Health, University of Queensland,
Royal Children’s Hospital, Brisbane; 2Department of Respiratory Medicine, Royal Children’s Hospital, Brisbane,
Australia
The aim of this study was to assess the validity of a number of bioelectrical impedance analysis (BIA) equations for the estimation of fat-free mass (FFM) in children and adolescents with cystic fibrosis (CF). The study involved 57 children and adolescents (27 females) with CF, aged between 5.3 and 17.9 years. Impedance measurements were taken and then converted to FFM using five selected equations. FFM measurements from dual energy X-ray absorptiometry (DEXA) were used as the comparison values. The bias, limits of agreements and correlation for four of the BIA equations were considered unacceptable when compared against the method of DEXA. From the equations examined, the equation of Houtkooper et al (bias = –0.3±1.7 kg; r=0.16) was considered the most suitable to determine FFM in children and adolescents with CF, however it was not deemed appropriate to be used interchangeably with DEXA measurements to monitor FFM in an individual. It is strongly recommended that disease-specific prediction equations are developed and tested for use in this population.
International Journal of Body Composition Research 2004, Vol. 2 No. 2: 75-77
C. Raja1, R. Hansen2, S. Colagiuri3 and B.J. Allen1,2
1Centre for Experimental Radiation Oncology, Cancer Care Centre, St. George Hospital, Kogarah, NSW 2217;
2Centre for In Vivo Body Composition, Royal North Shore Hospital, St. Leonards, NSW 2265 Australia; 3Department
of Endocrinology, Prince of Wales Hospital, Sydney, NSW 2031, Australia
There is a need for anthropometric equations to estimate adiposity in the field for Aboriginal Australian women. Twenty-four Aboriginal urban dwelling women were measured for height, weight, skinfolds and body fat. Total fat (kg) and body fat percentage (%BF) were obtained directly from dual energy X-ray absorptiometry (DEXA) scans. Skinfolds (biceps, triceps, subscapular and supra-iliac) were measured and the Durnin and Womersley equation was used to estimate %BF. The mean (SD) age of the women was 47 (14) years and the average body mass index (BMI) was 30.8 (7.8) kg/m2. Biceps, triceps, subscapular and supra-iliac skinfold were significantly correlated with measured %BF by DEXA (r = 0.83 to 0.89; P<0.001). Age was significantly correlated with both %BF estimated from skinfolds (r = 0.76, P<0.001) as well as %BF measured by DEXA (r = 0.68, P<0.01). Individual skinfolds and the sum of four skinfolds were highly correlated with %BF from DEXA, but the Durnin and Womersley equation underestimated %BF compared to DEXA. After correction of the Durnin and Womersley equation (%BF = 1.2* %BFD&W – 8.2), the SEE of predicted %BF was 3.2% with an explained variance of 0.88. It is concluded that the corrected anthropometric skinfold model can be applied in field studies as an alternative measure of total fat in Abroriginal Australian women.
International Journal of Body Composition Research 2004, Vol. 2 No. 2: 79-81
A. Aslani, B.A. Cooper, A. Sevette and R.C. Smith
Royal North Shore Hospital, St Leonards, NSW 2065, Australia
Changes in weight and body composition are expected after most major abdominal surgery. Excess fluid retention especially may result in major morbidity in the post-operative patients. Loss of weight, itself, has been generally addressed by administration of appropriate intervention procedures. However, the components of the weight change has to be determined if an efficient and effective intervention procedure is to be successfully administered. Total body protein, body fat and body water of 15 patients undergoing major upper gastrointestinal (GI) surgery were measured pre-operatively and two weeks post-operatively. Total body protein (TBP) was measured using the in-vivo neutron capture analysis (IVNCA) technique and total body water (TBW) using the isotope dilution technique. The nitrogen index (NI) was calculated from TBP and total body fat (FM), percentage body fat (%BF), fat-free mass (FFM) as well as the body mass index (BMI) from anthropometric measurements. Although there was a general increase in weight post-operatively, the majority of BC parameters (TBP, NI, FM, %BF, FFM and BMI) decreased, with the exception of TBW, which increased from 33.6 l to 38.1 l. The findings suggest that, in this group of surgical patients, the increase in weight observed post-operatively is due to an increase in the TBW. The findings also demonstrate the need to validate bedside techniques to measure the crucial TBW, which may be essential to the overall recovery and survival of this group of patients.
International Journal of Body Composition Research 2004, Vol. 2 No. 2: 83-90
Alireza Aslani1 and Ross C. Smith2
1Department of Nuclear Medicine, 2Department of Surgery (University of Sydney),
Royal North Shore Hospital, St Leonards, NSW 2065, Australia
Body composition measurements have been used for over 50 years to help define the nutritional deficiencies that result from illness, acute surgical stress and to guide therapies to correct these deficiencies. Direct measurement of body protein using in vivo neutron capture studies has been of great value in studying groups of surgical patients undergoing different therapeutic protocols. Understanding the errors of these measures helps to understand the meaning of the results obtained and the group sizes necessary to make meaningful comparisons. Losses of about 10 pe rcent of protein stores are needed to determine deficiencies in individual patients. Such losses do occur and have been shown to be predictive of complications of surgery, chemotherapy and renal dialysis. Bedside measures of Bioelectrical impedance analysis have yet to be incorporated in clinical practice although they have been shown to be able to measure fluid retention. Given that fluid retention and protein loss are related to poor outcome of different treatments the time is ready to introduce these measures into clinical practice.