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Steven B. Heymsfield - One of the best experts on this subject based on the ideXlab platform.

  • A New Total Body Potassium Method to Estimate Total Body Skeletal Muscle Mass in Children
    The Journal of nutrition, 2007
    Co-Authors: Z. Wang, Jack Wang, Stanley Heshka, Zhao Chen, Analiza M. Silva, Luís B. Sardinha, Dympna Gallager, Angelo Pietrobelli, Steven B. Heymsfield
    Abstract:

    A whole Body skeletal muscle [(SM); kg] mass estimation model, based on Total Body Potassium [(TBK); mmol] measured by whole Body (40)K counting (WBC) was developed (SM = 0.0082.TBK) and validated in adults in a previous study. It is unknown whether the adult TBK SM prediction model is applicable for pediatric use. The aim of this study was to derive and validate a pediatric TBK SM prediction equation. SM measured by MRI was used as the criterion and TBK was measured by WBC. The protocol was completed in 116 healthy children, 66 males and 50 females, 11.7 +/- 3.5 y (mean +/- SD, range = 5-17 y). A strong linear correlation was observed between TBK and SM (r = 0.984; P < 0.001). The SM:TBK ratio was 0.0071 +/- 0.0008 kg/mmol in the children studied, much lower than the corresponding value of 0.0082 kg/mmol in adults. An empirical SM prediction equation was developed using TBK alone: SM = 0.0085.TBK - 2.83, r(2) = 0.97, SEE = 1.39 kg. Bland-Altman analysis did not disclose a significant bias in the prediction of SM. When biological factors entered along with TBK in the general linear model, another prediction equation was developed: SM = 5.52 + 0.001.TBK (mmol) + 0.081.weight (kg) - 0.049.height (cm) + 0.00004.TBK . height + race (-0.60 for Caucasian, 0.49 for African-American, and 0 for Hispanic). Because the adult TBK SM prediction model is not applicable for pediatric use, this study provides new empirical TBK SM prediction equations that should prove useful for studies on nutrition, growth, and development in children.

  • Measuring partial Body Potassium in the arm versus Total Body Potassium
    Journal of applied physiology (Bethesda Md. : 1985), 2006
    Co-Authors: Lucian Wielopolski, Steven B. Heymsfield, L. M. Ramirez, Dympna Gallagher, Z. M. Wang
    Abstract:

    Skeletal muscle (SM), the Body's main structural support, has been implicated in metabolic, physiological, and disease processes in humans. Despite being the largest tissue in the human Body, its assessment remains difficult and indirect. However, being metabolically active it contains over 50% of the Total Body Potassium (TBK) pool. We present our preliminary results from a new system for measuring partial Body K (PBK) that presently are limited to the arm yet provide a direct and specific measure of the SM. This uniquely specific quantification of the SM mass in the arm, which is shielded from the Body during measurement, allows us to simplify the assumptions used in deriving the Total SM, thereby possibly improving the modeling of the human Body compartments. Preliminary results show that PBK measurements are consistent with those from the TBK previously obtained from the same subjects, thus offering a simpler alternative to computed tomography and magnetic resonance imaging used for the same purposes. The PBK system, which can be set up in a physician's office or bedside in a hospital, is completely passive, safe, and inexpensive; it can be used on immobilized patients, children, pregnant women, or other at-risk populations.

  • Total Body Protein Mass: Validation of Total Body Potassium Prediction Model in Children and Adolescents
    The Journal of nutrition, 2006
    Co-Authors: Zimian Wang, Jack Wang, Stanley Heshka, Steven B. Heymsfield
    Abstract:

    Protein is an important Body component for monitoring growth, development, and nutritional status. We previously developed a Total Body Potassium (TBK, in mmol) and bone mineral (Mo, in kg) model for predicting Total Body protein (TBPro, in kg) in adults (TBPro = 0.00252 x TBK + 0.732 x Mo). However, the applicability of the TBK-Mo model for children is unknown. The study aims were to develop a TBK-independent 6-component (6-C) TBPro approach as the criterion, and then to validate the TBK-Mo model in children. The following measurements were made in adolescents and children (n = 62, 38 boys and 24 girls, aged 5-17 y): Body weight (BW, in kg), Body volume (BV, in liters) by air displacement plethysmography, Total Body water (TBW, in kg) by 2H2O dilution, Mo by dual-energy X-ray absorptiometry, and TBK by whole-Body counting. A 6-C model was derived as TBPro = 2.922 x BW - 0.301 x TBW - 2.039 x Mo - 2.632 x BV. The TBPro estimates did not differ between the 6-C and TBK-Mo models (mean +/- SD, 0.20 +/- 0.86 kg). There was a significant correlation between TBPro by the 6-C and TBK-Mo models (r = 0.94, P 0.05). The TBK-Mo model can thus be used to estimate TBPro in healthy adults, adolescents, and children > 5 y old.

  • Total Body Potassium differs by sex and race across the adult age span
    The American journal of clinical nutrition, 2003
    Co-Authors: Moonseong Heo, Zimian Wang, Jack Wang, Richard N. Pierson, Steven B. Heymsfield, Stanley Heshka, Jeanine Albu, Dympna Gallagher
    Abstract:

    Background: Total Body Potassium (TBK) is an index of fat-free mass. Data describing changes in TBK in African American, Asian, or Hispanic populations have not been reported. Objective: The aim was to investigate possible sex and racial differences in TBK in adults over an age range of 70 y. Design: The study used longitudinal and cross-sectional data collected in a Body-composition unit from 973 men and 1368 women of African American, Asian, white, and Hispanic race-ethnicity. Random coefficient models in which baseline weight and height were taken into account were applied to estimate sex-specific changes in TBK among the 4 racial-ethnic groups. Results: The ages of 30 and 31 y were identified for women and men, respectively, as the cutoffs after which TBK began to decline. Both sexes had similar racial-ethnic patterns for expected mean TBK at the age cutoffs: African Americans had the highest value, followed by whites, Hispanics, and Asians. After the age cutoffs, the decline in TBK differed by race and sex. In women, African Americans showed the most rapid decline, whereas Asians had the lowest. In men, Hispanics had the most rapid decline in TBK, followed by African Americans, whites, and Asians. Conclusion: Significant sex and racial differences exist in the rate of change in TBK with age. Further studies are needed to explore the associations of declining TBK with health risks.

  • Whole-Body skeletal muscle mass: development and validation of Total-Body Potassium prediction models
    The American journal of clinical nutrition, 2003
    Co-Authors: Zimian Wang, Jack Wang, Richard N. Pierson, Shankuan Zhu, Steven B. Heymsfield
    Abstract:

    BACKGROUND A substantial proportion of Total Body Potassium (TBK) in humans is found in skeletal muscle (SM), thus affording a means of predicting Total-Body SM from whole-Body counter-measured (40)K. There are now > 30 whole-Body counters worldwide that have large cross-sectional and longitudinal TBK databases. OBJECTIVE We explored 2 SM prediction approaches, one based on the assumption that the ratio of TBK to SM is stable in healthy adults and the other on a multiple regression TBK-SM prediction equation. DESIGN Healthy subjects aged >or= 20 y were recruited for Body-composition evaluation. TBK and SM were measured by whole-Body (40)K counting and multislice magnetic resonance imaging, respectively. A conceptual model with empirically derived data was developed to link TBK and adipose tissue-free SM as the ratio of TBK to SM. RESULTS A Total of 300 subjects (139 men and 161 women) of various ethnicities with a mean (+/- SD) Body mass index (in kg/m(2)) of 25.1 +/- 5.4 met the study entry criteria. The mean conceptual model-derived TBK-SM ratio was 122 mmol/kg, which was comparable to the measurement-derived TBK-SM ratios in men and women (119.9 +/- 6.7 and 118.7 +/- 8.4 mmol/kg, respectively), although the ratio tended to be lower in subjects aged >or= 70 y. A strong linear correlation was observed between TBK and SM (r = 0.98, P < 0.001), with sex, race, and age as small but significant prediction model covariates. CONCLUSIONS Two different types of prediction models were developed that provide validated approaches for estimating SM mass from (40)K measurements by whole-Body counting. These methods afford an opportunity to predict SM mass from TBK data collected in healthy adults.

Jack Wang - One of the best experts on this subject based on the ideXlab platform.

  • A New Total Body Potassium Method to Estimate Total Body Skeletal Muscle Mass in Children
    The Journal of nutrition, 2007
    Co-Authors: Z. Wang, Jack Wang, Stanley Heshka, Zhao Chen, Analiza M. Silva, Luís B. Sardinha, Dympna Gallager, Angelo Pietrobelli, Steven B. Heymsfield
    Abstract:

    A whole Body skeletal muscle [(SM); kg] mass estimation model, based on Total Body Potassium [(TBK); mmol] measured by whole Body (40)K counting (WBC) was developed (SM = 0.0082.TBK) and validated in adults in a previous study. It is unknown whether the adult TBK SM prediction model is applicable for pediatric use. The aim of this study was to derive and validate a pediatric TBK SM prediction equation. SM measured by MRI was used as the criterion and TBK was measured by WBC. The protocol was completed in 116 healthy children, 66 males and 50 females, 11.7 +/- 3.5 y (mean +/- SD, range = 5-17 y). A strong linear correlation was observed between TBK and SM (r = 0.984; P < 0.001). The SM:TBK ratio was 0.0071 +/- 0.0008 kg/mmol in the children studied, much lower than the corresponding value of 0.0082 kg/mmol in adults. An empirical SM prediction equation was developed using TBK alone: SM = 0.0085.TBK - 2.83, r(2) = 0.97, SEE = 1.39 kg. Bland-Altman analysis did not disclose a significant bias in the prediction of SM. When biological factors entered along with TBK in the general linear model, another prediction equation was developed: SM = 5.52 + 0.001.TBK (mmol) + 0.081.weight (kg) - 0.049.height (cm) + 0.00004.TBK . height + race (-0.60 for Caucasian, 0.49 for African-American, and 0 for Hispanic). Because the adult TBK SM prediction model is not applicable for pediatric use, this study provides new empirical TBK SM prediction equations that should prove useful for studies on nutrition, growth, and development in children.

  • A New Total Body Potassium Method to Estimate Total Body Skeletal Muscle Mass
    2007
    Co-Authors: Zimian Wang, Jack Wang, Stanley Heshka, Zhao Chen, Analiza M. Silva, Luís B. Sardinha, Dympna Gallager, Steven B. Heymsf
    Abstract:

    A whole Body skeletal muscle [(SM); kg] mass estimation model, based on Total Body Potassium [(TBK); mmol] measured by whole Body 40 K counting (WBC) was developed (SM ¼ 0.0082� TBK) and validated in adults in a previous study. It is unknown whether the adult TBK SM prediction model is applicable for pediatric use. The aim of this study was to derive and validate a pediatric TBK SM prediction equation. SM measured by MRI was used as the criterion and TBK was measured by WBC. The protocol was completed in 116 healthy children, 66 males and 50 females, 11.7 6 3.5 y (mean 6 SD, range ¼ 5–17 y). A strong linear correlation was observed between TBK and SM (r ¼ 0.984; P , 0.001). The SM:TBK ratio was 0.0071 6 0.0008 kg/mmol in the children studied, much lower than the corresponding value of 0.0082 kg/mmol in adults. An empirical SM prediction equation was developed using TBK alone: SM ¼ 0.0085� TBK – 2.83, r 2 ¼ 0.97, SEE ¼ 1.39 kg. Bland-Altman analysis did not disclose a significant bias in the prediction of SM. When biological factors entered along with TBK in the general linear model, another prediction equation was developed: SM ¼ 5.52 1 0.001� TBK (mmol) 1

  • Total Body Protein Mass: Validation of Total Body Potassium Prediction Model in Children and Adolescents
    The Journal of nutrition, 2006
    Co-Authors: Zimian Wang, Jack Wang, Stanley Heshka, Steven B. Heymsfield
    Abstract:

    Protein is an important Body component for monitoring growth, development, and nutritional status. We previously developed a Total Body Potassium (TBK, in mmol) and bone mineral (Mo, in kg) model for predicting Total Body protein (TBPro, in kg) in adults (TBPro = 0.00252 x TBK + 0.732 x Mo). However, the applicability of the TBK-Mo model for children is unknown. The study aims were to develop a TBK-independent 6-component (6-C) TBPro approach as the criterion, and then to validate the TBK-Mo model in children. The following measurements were made in adolescents and children (n = 62, 38 boys and 24 girls, aged 5-17 y): Body weight (BW, in kg), Body volume (BV, in liters) by air displacement plethysmography, Total Body water (TBW, in kg) by 2H2O dilution, Mo by dual-energy X-ray absorptiometry, and TBK by whole-Body counting. A 6-C model was derived as TBPro = 2.922 x BW - 0.301 x TBW - 2.039 x Mo - 2.632 x BV. The TBPro estimates did not differ between the 6-C and TBK-Mo models (mean +/- SD, 0.20 +/- 0.86 kg). There was a significant correlation between TBPro by the 6-C and TBK-Mo models (r = 0.94, P 0.05). The TBK-Mo model can thus be used to estimate TBPro in healthy adults, adolescents, and children > 5 y old.

  • Total Body Potassium differs by sex and race across the adult age span
    The American journal of clinical nutrition, 2003
    Co-Authors: Moonseong Heo, Zimian Wang, Jack Wang, Richard N. Pierson, Steven B. Heymsfield, Stanley Heshka, Jeanine Albu, Dympna Gallagher
    Abstract:

    Background: Total Body Potassium (TBK) is an index of fat-free mass. Data describing changes in TBK in African American, Asian, or Hispanic populations have not been reported. Objective: The aim was to investigate possible sex and racial differences in TBK in adults over an age range of 70 y. Design: The study used longitudinal and cross-sectional data collected in a Body-composition unit from 973 men and 1368 women of African American, Asian, white, and Hispanic race-ethnicity. Random coefficient models in which baseline weight and height were taken into account were applied to estimate sex-specific changes in TBK among the 4 racial-ethnic groups. Results: The ages of 30 and 31 y were identified for women and men, respectively, as the cutoffs after which TBK began to decline. Both sexes had similar racial-ethnic patterns for expected mean TBK at the age cutoffs: African Americans had the highest value, followed by whites, Hispanics, and Asians. After the age cutoffs, the decline in TBK differed by race and sex. In women, African Americans showed the most rapid decline, whereas Asians had the lowest. In men, Hispanics had the most rapid decline in TBK, followed by African Americans, whites, and Asians. Conclusion: Significant sex and racial differences exist in the rate of change in TBK with age. Further studies are needed to explore the associations of declining TBK with health risks.

  • Whole-Body skeletal muscle mass: development and validation of Total-Body Potassium prediction models
    The American journal of clinical nutrition, 2003
    Co-Authors: Zimian Wang, Jack Wang, Richard N. Pierson, Shankuan Zhu, Steven B. Heymsfield
    Abstract:

    BACKGROUND A substantial proportion of Total Body Potassium (TBK) in humans is found in skeletal muscle (SM), thus affording a means of predicting Total-Body SM from whole-Body counter-measured (40)K. There are now > 30 whole-Body counters worldwide that have large cross-sectional and longitudinal TBK databases. OBJECTIVE We explored 2 SM prediction approaches, one based on the assumption that the ratio of TBK to SM is stable in healthy adults and the other on a multiple regression TBK-SM prediction equation. DESIGN Healthy subjects aged >or= 20 y were recruited for Body-composition evaluation. TBK and SM were measured by whole-Body (40)K counting and multislice magnetic resonance imaging, respectively. A conceptual model with empirically derived data was developed to link TBK and adipose tissue-free SM as the ratio of TBK to SM. RESULTS A Total of 300 subjects (139 men and 161 women) of various ethnicities with a mean (+/- SD) Body mass index (in kg/m(2)) of 25.1 +/- 5.4 met the study entry criteria. The mean conceptual model-derived TBK-SM ratio was 122 mmol/kg, which was comparable to the measurement-derived TBK-SM ratios in men and women (119.9 +/- 6.7 and 118.7 +/- 8.4 mmol/kg, respectively), although the ratio tended to be lower in subjects aged >or= 70 y. A strong linear correlation was observed between TBK and SM (r = 0.98, P < 0.001), with sex, race, and age as small but significant prediction model covariates. CONCLUSIONS Two different types of prediction models were developed that provide validated approaches for estimating SM mass from (40)K measurements by whole-Body counting. These methods afford an opportunity to predict SM mass from TBK data collected in healthy adults.

Zimian Wang - One of the best experts on this subject based on the ideXlab platform.

  • A New Total Body Potassium Method to Estimate Total Body Skeletal Muscle Mass
    2007
    Co-Authors: Zimian Wang, Jack Wang, Stanley Heshka, Zhao Chen, Analiza M. Silva, Luís B. Sardinha, Dympna Gallager, Steven B. Heymsf
    Abstract:

    A whole Body skeletal muscle [(SM); kg] mass estimation model, based on Total Body Potassium [(TBK); mmol] measured by whole Body 40 K counting (WBC) was developed (SM ¼ 0.0082� TBK) and validated in adults in a previous study. It is unknown whether the adult TBK SM prediction model is applicable for pediatric use. The aim of this study was to derive and validate a pediatric TBK SM prediction equation. SM measured by MRI was used as the criterion and TBK was measured by WBC. The protocol was completed in 116 healthy children, 66 males and 50 females, 11.7 6 3.5 y (mean 6 SD, range ¼ 5–17 y). A strong linear correlation was observed between TBK and SM (r ¼ 0.984; P , 0.001). The SM:TBK ratio was 0.0071 6 0.0008 kg/mmol in the children studied, much lower than the corresponding value of 0.0082 kg/mmol in adults. An empirical SM prediction equation was developed using TBK alone: SM ¼ 0.0085� TBK – 2.83, r 2 ¼ 0.97, SEE ¼ 1.39 kg. Bland-Altman analysis did not disclose a significant bias in the prediction of SM. When biological factors entered along with TBK in the general linear model, another prediction equation was developed: SM ¼ 5.52 1 0.001� TBK (mmol) 1

  • Total Body Protein Mass: Validation of Total Body Potassium Prediction Model in Children and Adolescents
    The Journal of nutrition, 2006
    Co-Authors: Zimian Wang, Jack Wang, Stanley Heshka, Steven B. Heymsfield
    Abstract:

    Protein is an important Body component for monitoring growth, development, and nutritional status. We previously developed a Total Body Potassium (TBK, in mmol) and bone mineral (Mo, in kg) model for predicting Total Body protein (TBPro, in kg) in adults (TBPro = 0.00252 x TBK + 0.732 x Mo). However, the applicability of the TBK-Mo model for children is unknown. The study aims were to develop a TBK-independent 6-component (6-C) TBPro approach as the criterion, and then to validate the TBK-Mo model in children. The following measurements were made in adolescents and children (n = 62, 38 boys and 24 girls, aged 5-17 y): Body weight (BW, in kg), Body volume (BV, in liters) by air displacement plethysmography, Total Body water (TBW, in kg) by 2H2O dilution, Mo by dual-energy X-ray absorptiometry, and TBK by whole-Body counting. A 6-C model was derived as TBPro = 2.922 x BW - 0.301 x TBW - 2.039 x Mo - 2.632 x BV. The TBPro estimates did not differ between the 6-C and TBK-Mo models (mean +/- SD, 0.20 +/- 0.86 kg). There was a significant correlation between TBPro by the 6-C and TBK-Mo models (r = 0.94, P 0.05). The TBK-Mo model can thus be used to estimate TBPro in healthy adults, adolescents, and children > 5 y old.

  • Total Body Potassium differs by sex and race across the adult age span
    The American journal of clinical nutrition, 2003
    Co-Authors: Moonseong Heo, Zimian Wang, Jack Wang, Richard N. Pierson, Steven B. Heymsfield, Stanley Heshka, Jeanine Albu, Dympna Gallagher
    Abstract:

    Background: Total Body Potassium (TBK) is an index of fat-free mass. Data describing changes in TBK in African American, Asian, or Hispanic populations have not been reported. Objective: The aim was to investigate possible sex and racial differences in TBK in adults over an age range of 70 y. Design: The study used longitudinal and cross-sectional data collected in a Body-composition unit from 973 men and 1368 women of African American, Asian, white, and Hispanic race-ethnicity. Random coefficient models in which baseline weight and height were taken into account were applied to estimate sex-specific changes in TBK among the 4 racial-ethnic groups. Results: The ages of 30 and 31 y were identified for women and men, respectively, as the cutoffs after which TBK began to decline. Both sexes had similar racial-ethnic patterns for expected mean TBK at the age cutoffs: African Americans had the highest value, followed by whites, Hispanics, and Asians. After the age cutoffs, the decline in TBK differed by race and sex. In women, African Americans showed the most rapid decline, whereas Asians had the lowest. In men, Hispanics had the most rapid decline in TBK, followed by African Americans, whites, and Asians. Conclusion: Significant sex and racial differences exist in the rate of change in TBK with age. Further studies are needed to explore the associations of declining TBK with health risks.

  • Whole-Body skeletal muscle mass: development and validation of Total-Body Potassium prediction models
    The American journal of clinical nutrition, 2003
    Co-Authors: Zimian Wang, Jack Wang, Richard N. Pierson, Shankuan Zhu, Steven B. Heymsfield
    Abstract:

    BACKGROUND A substantial proportion of Total Body Potassium (TBK) in humans is found in skeletal muscle (SM), thus affording a means of predicting Total-Body SM from whole-Body counter-measured (40)K. There are now > 30 whole-Body counters worldwide that have large cross-sectional and longitudinal TBK databases. OBJECTIVE We explored 2 SM prediction approaches, one based on the assumption that the ratio of TBK to SM is stable in healthy adults and the other on a multiple regression TBK-SM prediction equation. DESIGN Healthy subjects aged >or= 20 y were recruited for Body-composition evaluation. TBK and SM were measured by whole-Body (40)K counting and multislice magnetic resonance imaging, respectively. A conceptual model with empirically derived data was developed to link TBK and adipose tissue-free SM as the ratio of TBK to SM. RESULTS A Total of 300 subjects (139 men and 161 women) of various ethnicities with a mean (+/- SD) Body mass index (in kg/m(2)) of 25.1 +/- 5.4 met the study entry criteria. The mean conceptual model-derived TBK-SM ratio was 122 mmol/kg, which was comparable to the measurement-derived TBK-SM ratios in men and women (119.9 +/- 6.7 and 118.7 +/- 8.4 mmol/kg, respectively), although the ratio tended to be lower in subjects aged >or= 70 y. A strong linear correlation was observed between TBK and SM (r = 0.98, P < 0.001), with sex, race, and age as small but significant prediction model covariates. CONCLUSIONS Two different types of prediction models were developed that provide validated approaches for estimating SM mass from (40)K measurements by whole-Body counting. These methods afford an opportunity to predict SM mass from TBK data collected in healthy adults.

  • Magnitude and variation of ratio of Total Body Potassium to fat-free mass: a cellular level modeling study.
    American journal of physiology. Endocrinology and metabolism, 2001
    Co-Authors: Zimian Wang, F. Xavier Pi-sunyer, Donald P. Kotler, Jack Wang, Richard N. Pierson, Steven B. Heymsfield
    Abstract:

    Potassium is an essential element of living organisms that is found almost exclusively in the intracellular fluid compartment. The assumed constant ratio of Total Body Potassium (TBK) to fat-free m...

Kenneth J. Ellis - One of the best experts on this subject based on the ideXlab platform.

  • Total Body Potassium revisited.
    European journal of clinical nutrition, 2013
    Co-Authors: Alexia J. Murphy, Kenneth J. Ellis, Anura V. Kurpad, Tom Preston, C Slater
    Abstract:

    There are a multitude of methods available today that can be used to assess Body composition in humans, from pre-term infants to the oldest adults. A Body composition method is usually focused at a specific component of Body composition, such as fat mass, Total Body water (TBW) or Body cell mass (BCM). Many methods have been developed over the past century, with one of the earliest measures of Body composition being Total Body Potassium counting (TBK), which was first recognized in 1950s. There were a large number of whole Body counters (WBC) available in 1970s,1 but over time the use of TBK facilities has decreased and old counters have been decommissioned. With other more accessible Body composition technologies becoming more commonplace, today TBK is a rarely utilized method. However, as no alternative technology provides a direct and precise measure of BCM,2 the need for accurate Body composition techniques for clinical and public health demands that TBK counting as a method should be revisited.

  • Incidence and consequences of Total Body Potassium depletion in chronic hemodialysis patients.
    Frontiers in bioscience : a journal and virtual library, 2003
    Co-Authors: G. M. Dolson, Kenneth J. Ellis, Michael L Johnson, Horacio J. Adrogué
    Abstract:

    OBJECTIVE This study determined relationship between Total Body Potassium (TBK) and morbidity and mortality of patients with end stage renal disease (ESRD). DESIGN, PATIENTS, SETTING: Long term observational study of 15 ESRD patients receiving chronic hemodialysis in an academically affiliated Veterans Affairs Medical Center Hospital. METHODOLOGY AND OUTCOME MEASURE: TBK by whole-Body counting of 40K, dialysis Potassium losses, and patient demographic characteristics were determined. Survival was evaluated retrospectively after seven years of follow-up. RESULTS Six of 15 patients (40%) had TBK depletion. All patients who were TBK depleted, expired by study end. In contrast, only 4 of 9 patients with normal K+ stores had died during the same time period (P

  • incidence and consequences of Total Body Potassium depletion in chronic hemodialysis patients
    Frontiers in Bioscience, 2003
    Co-Authors: G. M. Dolson, Kenneth J. Ellis, Michael L Johnson, Horacio J. Adrogué
    Abstract:

    OBJECTIVE This study determined relationship between Total Body Potassium (TBK) and morbidity and mortality of patients with end stage renal disease (ESRD). DESIGN, PATIENTS, SETTING: Long term observational study of 15 ESRD patients receiving chronic hemodialysis in an academically affiliated Veterans Affairs Medical Center Hospital. METHODOLOGY AND OUTCOME MEASURE: TBK by whole-Body counting of 40K, dialysis Potassium losses, and patient demographic characteristics were determined. Survival was evaluated retrospectively after seven years of follow-up. RESULTS Six of 15 patients (40%) had TBK depletion. All patients who were TBK depleted, expired by study end. In contrast, only 4 of 9 patients with normal K+ stores had died during the same time period (P<0.02). Median survival time of subjects with normal TBK was 100 vs 55 months for the depleted group (chi2=4.6, P<0.05). Patients with normal TBK were younger (41.9 vs 62.5 years, P<0.02) and predominantly black (78%). The ESRD group with normal TBK received more hours of hemodialysis (HD) per week (11.2 hours vs 9.7, P<0.02) and had greater K+ removal than the depleted patients (70.5 mmol/treatment vs 43.8). Urea reduction ratio was not statistically different between groups. Serum albumin, interdialytic increases in BUN and weight, and Body mass index were not different between normal and TBK depleted groups. CONCLUSIONS TBK depletion occurs in a significant proportion of HD patients and is associated with increased mortality. It is prudent to customize HD and dietary prescriptions to maintain normal levels of TBK in ESRD patients.

  • fat mass in infants and toddlers comparability of Total Body water Total Body Potassium Total Body electrical conductivity and dual energy x ray absorptiometry
    Journal of Pediatric Gastroenterology and Nutrition, 1999
    Co-Authors: Nancy F Butte, Roman J. Shypailo, Carolyn J Heinz, Judy M Hopkinson, William W Wong, Kenneth J. Ellis
    Abstract:

    Backgruund: Accuratc assessment of Body composition in in­ rants ami chi Idren is fundamental to understanding normal growth and development. Validation of methods applicable to pediatric populations is needed. In the absence of a gold stan­ dard, thi, study was conducted 10 compare methods using Total Body water. Total Body Potassium, Total Body electrical conduc­ tivity. ami dual energy x-ray absorptiometry measurements for thc estimation or Body rat mass in infants and toddlers. Methods: Repeated Body composition measurements were per­ formed on 7b healthy term infants at 0.5, 3. 6, 9, 12, 18. and 24 months of age. Total Body water was determined by deuterium dililtion and convcrted to fat-free mass. Total Body electrical conductivity was used 10 measure fat mass. Total Body potas­ sillm was estimated by whole-Body counting and converted to l'at-1'I'<:e mass. Dual-energy x-ray absorptiometry was used to estimate fat lIIass at 0.5. 12. and 24 months only. Data were analyzed by repeated measures analysis of variance. followed by Bonferroni multiple comparisons at Vft. Results: Significalll differences among methods were encoulI­ tered at eaeh age (p = 0.001-0.05). The rank order or the methods and the magnitude of the method dilTerenccs were a function of age, not of gender or infant feeding ll1ode. Wide limits of agreement imply that the methods arc not interchange­ able for group or individual measurements. Conclusions: Methods using Total Body water. Total Body po­ tassium, Total Body electrical condudivity, and dual-energy x­ ray absorptiometry to estimate Body fat mass in illfanls and toddlers are not interchangeable and require further develop­ ment and validation. jPN 29:184-189, 1.999. Key Words: Body composition-Dual-energy x-ray absorptioll1etry-Fat­ free mass-Fat mass-Infants--Toddlers-Total hody wa­ ter--Total Body Potassium~-Total Body elt-elrical C(llldUcli\­

  • Total Body Potassium in the infant
    Journal of Radioanalytical and Nuclear Chemistry Articles, 1992
    Co-Authors: Kenneth J. Ellis, Roman J. Shypailo
    Abstract:

    We have examined several whole Body counting geometries for exclusive use in Total Body Potassium (TBK) measurements in preterm infants. This paper describes two counters, one for very-low-birth-weight (VLBW) infants with Body weights under 2000 g, and a second counter for larger preterm infants. Both systems use large-volume NaI(Tl) detectors (10.2 cm × 10.2 cm × 45.7 cm) and are operated in a low background room. The standard error for a TBK measurement decreases from 5% at 1 kg Body weight to 2% at 4.5 kg weight.

Barry J Allen - One of the best experts on this subject based on the ideXlab platform.

  • Calibration of a Total Body Potassium monitor with an anthropomorphic phantom
    Physics in medicine and biology, 1996
    Co-Authors: R D Hansen, Barry J Allen
    Abstract:

    An anthropomorphic phantom was used to calibrate a supine geometry sodium iodide Total Body Potassium monitor. Correction factors accommodating variability in subject size were empirically determined. Measurements on 12 males of weight 45 - 96 kg, height 161 - 184 cm and 18 females of weight 48 - 89 kg, height 153 - 175 cm, showed that the calibration factor was significantly correlated (r = 0.88, p < 0.0001) to subject , indicating comparable accuracy to -based calibration procedures. Fat-free mass determined from the Potassium measurements of 16 subjects correlated significantly with fat-free mass estimated from skinfold thickness (r = 0.98, p < 0.0001), dual-energy x-ray absorptiometry (r = 0.99, p < 0.0001) and bioimpedance analysis (r = 0.98, p < 0.0001). These data, together with the precision (coefficient of variation, CV = 1.5%) and accuracy (CV = 4.5%) of the system, indicate that this calibration procedure represents a relatively low-cost, non-invasive alternative to -based methods of calibrating Total Body Potassium monitors.