Comparison of total body potassium with other techniques for measuring lean body mass in men and women with AIDS wasting

BACKGROUND: Lean body mass is an important predictor of survival and functional status in patients with AIDS wasting. The bias between different techniques for assessing body composition in AIDS wasting is not known. DESIGN: We compared total body potassium (TBK) with fat-free mass (FFM) determined by dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA), and skinfold-thickness measurement (SKF) in 132 patients (63 men, 69 women) with AIDS wasting (weight < 90% of ideal body weight, or weight loss > 10% of original, or both). None of the subjects exhibited clinical lipodystrophy. Comparisons were made by using different BIA equations. RESULTS: Lean body mass determined by DXA was highly correlated with TBK in men (r = 0.79, P: < 0.0001) and women (r = 0.84, P: < 0.0001). FFM(BIA) and FFM(DXA) were significantly different (P: < 0.01 in men and P: < 0.0001 in women). The difference between FFM(DXA) and FFM(BIA) was significantly greater with greater weight and body fat, particularly in HIV-infected women (r = -0.39, P: = 0.001 for weight; r = -0.60, P: < 0.0001 for fat). The comparability of FFM and fat mass determined by DXA and BIA was dependent on the specific BIA equation used. Among men, no single BIA equation was more highly predictive of fat mass and FFM in comparison with DXA. CONCLUSIONS: The differences between DXA, BIA, and SKF in the determination of fat mass and FFM are significant in patients with AIDS wasting. BIA overestimates FFM compared with DXA in those with greater body fat. Standard BIA equations may not accurately estimate FFM and fat mass in men and women with AIDS wasting.     

Fat-free mass in chronic illness: comparison of bioelectrical impedance and dual-energy x-ray absorptiometry in 480 chronically ill and healthy subjects.

Assessment of fat-free mass (FFM) and fat mass in ambulatory and hospitalized patients permits optimal adaptation of nutrition support. Recent methods for the determination of FFM are dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA). The purpose of this study was to determine if the BIA-determined FFM as estimated by the formula by Kotler et al. and the Geneva formula could be validated when compared to DXA-determined FFM in subjects with various diagnoses. Body composition was measured by BIA and DXA in 480 subjects including healthy young men and women, elite female runners, and patients with various pathologies (including chronic obstructive and restrictive pulmonary disease patients; cystic fibrosis patients; lung, heart, and liver transplantation patients [both pre- and post-], and hemiplegic and AIDS patients). The present results suggest that BIA is relevant in the clinical assessment of body composition, but BIA formulas appropriate to the subject pool must be used for evaluation of FFM and fat mass. The BIA formula by Kotler et al. is appropriate for healthy subjects and patients with AIDS, cystic fibrosis, and pre- or postliver transplantation. The Geneva formula is more appropriate in pulmonary diseases and hemiplegic subjects with normal weight.     

A validation study of body composition by bioelectrical impedance analysis in human immunodeficiency virus (HIV)-positive and HIV-negative Hispanic men and women

Bioelectrical impedance analysis (BIA) is a potentially useful tool for measuring body composition in people with human immunodeficiency virus (HIV). However, it is not clear that equations derived in healthy non-Hispanic whites can be applied to people who are of other races or ethnicities and who are infected with HIV. Body composition measures done by BIA, using the equations of Lukaski, were compared to measures of body composition derived from dual-energy x-ray absorptiometry (DXA) in Hispanic men and women of Caribbean origin (predominantly Puerto Rican) with and without HIV infection. In cross-sectional analyses, body composition was measured by BIA and DXA in four groups of Hispanics: 97 HIV-positive men, 70 HIV-negative men, 38 HIV-positive women, and 14 HIV-negative women. The method of Bland and Altman was used to evaluate the validity of BIA compared to DXA. Compared to DXA, BIA provided accurate measures of fat-free mass in HIV-positive and HIV-negative Hispanic men. Fat-free mass by BIA compared to DXA was overestimated by 2.7 kg (standard deviation=2.5; P<0.0001) in the HIV-positive Hispanic women and by 3.4 kg (standard deviation=2.6; P<0.01) in the HIV-negative women. The magnitude of the bias in fat-free mass was dependent on fat mass in both the men and the women. BIA, using the equations of Lukaski, appears to be useful in this Hispanic population of Caribbean origin with and without HIV, for whom it provided reasonable estimates of body composition. Fat mass affects the accuracy of estimates.     

Bioelectrical impedance vs air displacement plethysmography and dual-energy X-ray absorptiometry to determine body composition in patients with end-stage renal disease

BACKGROUND: Patients with end-stage renal disease (ESRD) have significant shifts in fluid homeostasis that may impair measurements of body composition using methods based upon determinations of body water. Estimates of body water are fundamental for bioelectrical impedance analysis (BIA), which measures electrical resistance to estimate total body water and body composition. METHODS: BIA was compared with 2 other techniques: (1) air displacement plethysmography (ADP), which relies on measurements of body density to estimate body fat and fat-free masses; and (2) dual-energy x-ray absorptiometry (DXA), which depends on the relative attenuation of an x-ray beam to produce images of body fat and bone mineral. In study 1, BIA and ADP were performed on 38 ESRD patients (21 men and 17 women; age 51.3 +/- 2.2 years; weight 79.8 +/- 2.9 kg; body mass index [BMI] 27.4 +/- 0.9 kg/m2). In study 2, BIA and DXA were performed on 47 patients (22 men and 25 women; age 52.7 +/- 2.3 years; weight 73.6 +/- 2.9 kg; BMI 25.9 +/- 1.0 kg/m2). RESULTS: The ranges of percent body fat using BIA in studies 1 and 2 were from 7% to 57% and from 6% to 52%, respectively. Percent body fat measurements were significantly (p < .0001) correlated for BIA vs ADP (r = .74) and for BIA vs DXA (r = .84). Mean body fat as determined by BIA and ADP in study 1 was 31.8 +/- 2.0% and 36.3 +/- 1.8%* and by BIA and DXA in study 2 was 29.6 +/- 1.5% and 31.8 +/- 1.8%*, respectively (*p < .05 vs BIA). All 3 methods had similar variability associated with their measurements (coefficients of variation approximately 5%). The average body fat measured by BIA was less than ADP or DXA, regardless of gender or race. Furthermore, the variation was not greater at lower or higher body fat values. CONCLUSIONS: Body fat measurements using ADP and DXA were correlated with those using BIA across a relatively wide range of body fat levels in adults with ESRD. However, BIA appeared to underestimate body fat and overestimate fat-free mass, possibly because of increased measurements of body water. Because ADP is convenient and does not use body water content in determination of body density and body composition, it has very good potential as a relatively new technique to estimate percent body fat in adults with ESRD.     

Troubles nutritionnels lors de la sclérose latérale amyotrophique (SLA)

Amyotrophic lateral sclerosis (ALS) is a rare neuromuscular disease, with a severe prognostic. Its consequences are not only neurological, but also nutritional, linked with a decrease of feeding, caused by swallowing and salivation disorders, a frequent anorexia or constipation, troubles due to a possible respiratory insufficiency, and sometimes important difficulties for going shopping, cooking and more simply putting the food into the mouth. Although fat-free mass is usually decreased during ALS, a paradoxical hypermetabolism is present in 50 to 70% cases, favouring nutritional alterations. The tools used for assessment, sometimes specific to the disability, are anthropometric criteria, body impedance analysis (BIA), dietetic surveys, dual X-ray absorptiometry and indirect calorimetry. Alimentary intakes, weight, fat-free mass and body mass index are progressively reduced, leading to malnutrition. BIA phase angle is largely decreased, reflecting severe cellular alterations. Disorders of lipid status are possible but inconsistent across studies and perhaps linked with cultural feeding habits. The loss of weight at diagnosis and malnutrition during evolution are independent prognostic factors for survival, justifying early nutritional assessment and care. During evolution of ALS, a higher level of fat mass seems to be a positive factor for survival. French, European and American recommendations give precisions on follow-up, modalities of fight against the causes of malnutrition, nutritional care, mainly including the use of oral energy and protein-enriched nutritional supplements and enteral nutrition.     

Proportional bias between dual-energy x-ray absorptiometry and bioelectrical impedance analysis varies based on sex in active adults consuming high- and low-carbohydrate diets

Dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) are common methods of body composition assessment, but the agreement between these methods varies. Bias between DXA and single-frequency BIA was evaluated at 6 different time points in 48 active male and female adults consuming standardized high- and low-carbohydrate diets. It was hypothesized that fixed and proportional biases exist between DXA and BIA but that the extent of bias does not differ based on sex. Substantial fixed bias was present for estimates obtained by DXA and BIA, and both men and women exhibited proportional bias for fat mass (FM) and fat-free mass (FFM). The magnitude of bias was greater in women, and only women exhibited proportional bias for body fat percentage. In individuals with less FM, the mean difference between DXA and BIA was high, indicating that BIA underestimated FM relative to DXA. However, in individuals with greater FM, better agreement was seen. Correspondingly, the mean difference in FFM estimates was greater in individuals with less FFM. In some individuals with high quantities of FM or FFM relative to the sample, the relationship between devices was reversed such that BIA overestimated FM and underestimated FFM. The degree of disagreement between DXA and BIA varies substantially based on body size and sex such that all-encompassing statements regarding the comparability of these technologies cannot presently be made.     

Body composition assessment in adults with cystic fibrosis: comparison of dual-energy X-ray absorptiometry with skinfolds and bioelectrical impedance analysis

OBJECTIVE: We compared body composition measurement in adults with cystic fibrosis (CF) by using non-invasive methods (skinfold thicknesses and bioelectrical impedance analysis [BIA]) with dual-energy X-ray absorptiometry (DXA). METHODS: Seventy-six adults with CF (mean age 29.9 +/- 7.9 y, mean body mass index 21.5 +/- 2.5 kg/m(2)) were studied. Body composition was measured to calculate fat-free mass (FFM) using DXA, the sum of four skinfold thicknesses, and BIA (predictive equations of Lukaski and of Segal). RESULTS: Mean FFM values +/- standard deviation measured using DXA were 54.8 +/- 7.3 kg in men and 41.2 +/- 3.9 kg in women. Mean FFM values measured using BIA/Lukaski were 51.5 +/- 7.8 kg in men and 40.4 +/- 4.9 kg in women (P < 0.0005 for men, not significant for women for comparison with DXA). Mean FFM values measured using BIA/Segal were 54.2 +/- 7.5 kg for men and 44.1 +/- 5.9 kg for women (not significant for men, P < 0.0005 for women for comparison with DXA). Mean FFM values measured using skinfolds were significantly higher than those for FFM with DXA (57.2 +/- 7.2 kg in men, 43.3 +/- 4.3 kg in women, P < 0.0005 for comparison with DXA). The 95% limits of agreement with FFM using DXA were, for men and women, respectively, -8.3 to 1.7 kg and -6.4 to 4.8 kg for BIA/Lukaski, -4.8 to 3.6 kg and -3.1 to 8.9 kg for BIA/Segal, and -2.8 to 7.3 kg and -1.5 to 5.7 kg for skinfolds. CONCLUSION: This study suggests that skinfold thickness measurements and BIA will incorrectly estimate FFM in many adults with CF compared with DXA measurements of FFM. These methods have limited application in the assessment of body composition in individual adult patients with CF.     

Body Composition Measurement in Bronchiectasis: Comparison between Bioelectrical Impedance Analysis,Skinfold Thickness Measurement,and Dual-Energy X-ray Absorptiometry before and after Pulmonary Rehabilitation

Background

In individuals with bronchiectasis, fat-free mass depletion may be common despite a low prevalence of underweight and is considered a risk factor for increased morbidity and mortality. Techniques to adequately estimate fat-free mass and its changes over time are needed.

Rheumatoid cachexia,central obesity and malnutrition in patients with low-active rheumatoid arthritis: feasibility of anthropometry,Mini Nutritional Assessment and body composition techniques

Background and aims  The concurrent decrease in fat free mass (FFM) and increase in fat mass (FM), including central obesity, in patients with rheumatoid arthritis (RA) may be related to increased cardiovascular morbidity as well as to functional decline. The objectives of this study were to evaluate body composition and nutritional status in patients with RA and the feasibility of bioelectrical impedance (BIA) to detect rheumatoid cachexia. Methods  Eighty RA outpatients (76% women), mean age 61 (range 22–80) years and with mean disease duration of 6 (range 1–52) years, were assessed by body mass index (BMI), waist circumference (WC), whole-body dual-energy X-ray absorptiometry (DXA), BIA and the Mini Nutritional Assessment (MNA). Results  Fat free mass index (FFMI; kg/m²) was low in 26% of the women and in 21% of the men. About every fifth patient displayed concomitant low FFMI and elevated fat mass index (FMI; kg/m²), i.e. rheumatoid cachexia. BMI and MNA were not able to detect this condition. Sixty-seven percent had increased WC. Reduced FFM was independently related to age (p = 0.022), disease duration (p = 0.027), ESR (p = 0.011) and function trendwise (p = 0.058). There was a good relative agreement between DXA and BIA (FM r ² = 0.94, FFM r ² = 0.92; both p < 0.001), but the limits of agreement were wide for each variable, i.e. for FM −3.3 to 7.8 kg; and for FFM −7.9 to 3.7 kg. Conclusion  Rheumatoid cachexia and central obesity were common in patients with RA. Neither BMI nor MNA could detect this properly. There was a good relative agreement between DXA and BIA, but the limits of agreement were wide, which may restrict the utility of BIA in clinical practice. This work has in part been presented at the Congress of American College of Rheumatology in San Francisco, October 2008.     

Evaluation of Nutritional Status and Methods to Identify Nutritional Risk in Rheumatoid Arthritis and Spondyloarthritis

Patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA) experience several nutritional challenges and are prone to develop malnutrition. This observational study aimed to perform a comprehensive nutritional assessment of outpatients diagnosed with RA and SpA, as well as to evaluate methods to identify nutritional risk. Nutritional status was investigated by anthropometric measures, body composition (DXA, dual energy X-ray absorptiometry), and handgrip strength (HGS). Nutritional risk was classified by Nutritional Risk Screening 2002 (NRS2002) and malnutrition was defined by the Global Leadership Initiative on Malnutrition (GLIM) criteria and fat-free mass index (FFMI; kg/m², <16.7 (M), <14.6 (F)). Out of 71 included patients, 46 (66%) were abdominally obese, 28 (39%) were obese in terms of body mass index (BMI), and 33 (52%) were obese in terms of the fat mass index (FMI; kg/m², ≥8.3 (M), ≥11.8 (F)). Malnutrition was identified according to FFMI in 12 (19%) patients, according to GLIM criteria in 5 (8%) patients, and on the basis of BMI (<18.5 kg/m²) in 1 (1%) patient. None were identified by NRS2002 to be at nutritional risk. Our study revealed high prevalence of abdominal obesity and low FFMI. Waist circumference was a good indicator of FMI. BMI, NRS2002, and HGS did not capture patients with malnutrition identified by DXA.     

Fat-Free Mass Depletion and Inflammation in Patients with Bronchiectasis

Fat-free mass depletion has been related to increased inflammatory activity and to increased morbidity and mortality in chronic respiratory diseases. The aims of our study were to determine the nutritional status and serum levels of adipocytokines and inflammatory cytokines in patients with bronchiectasis of any etiology and their relation with respiratory parameters. A cross-sectional study was designed that included patients aged >14 years with diagnostic criteria for bronchiectasis. Anthropometric parameters; a diet questionnaire; hand grip dynamometry; levels of leptin, adiponectin, interleukin-6 (IL-6), tumor necrosis factor-α, and ultrasensitive C-reactive protein; as well as respiratory parameters (ie, clinical, radiologic, and spirometric values) were assessed. Ninety-three clinically stable patients were recruited, 43 with cystic fibrosis, 31 with noncystic fibrosis bronchiectasis, and 19 with cystic fibrosis transmembrane conductance regulator-related bronchiectasis. Fat-free mass depletion was present in 31% of patients, with no differences according to the etiology of the bronchiectasis. Correlations were found between inflammatory cytokines (ie, IL-6) and exacerbations, bronchorrea, forced expiratory volume in 1 second, and Bhalla score. Patients with worse respiratory disease severity, malnutrition, and diabetes had significantly higher levels of IL-6. Adiponectin correlated significantly and positively with fat mass and fat mass index and negatively with fat-free mass, fat-free mass index, and hand dynamometry. Leptin correlated positively with body mass index, fat mass and fat mass index, and negatively with fat-free mass, fat-free mass index, and dynamometry. Patients with bronchiectasis present a high percentage of fat-free mass depletion, independent of the etiology of the disease. The levels of inflammatory cytokines (especially IL-6) may be useful markers of disease severity. Adiponectin levels were higher in patients with fat-free mass depletion.     

Underweight patients with anorexia nervosa: comparison of bioelectrical impedance analysis using five equations to dual X-ray absorptiometry

Background & aims

Body weight changes do not reflect the respective changes of body compartments, namely fat-free mass (FFM) and fat mass (FM). Both bioelectrical Impedance Analysis (BIA) and the Dual X-ray absorptiometry (DXA) measure FFM and FM.This study in underweight patients with anorexia nervosa (AN) aims to compare measurements of FM and FFM done by DXA and BIA using 5 different BIA equations already validated in healthy population and to identify the most suitable BIA equation for AN patients.

Methods

Fifty female patients with AN (BMI = 14.3 ± 1.49, age = 19.98 ± 5.68 yrs) were included in the study. Body composition was measured by DXA (Delphi W, Hologic, Bedford, MA) and by 50 kHz BIA (FORANA, Helios) using 5 different BIA equations validated in healthy population (Sun, Geneva, Kushner, Deurenberg and Roubenoff equations). Comparison between the DXA and the 5 BIA equations was done using the sum of the squares of differences and Bland–Altman plots.

Results

The Deurenberg equation gave the best estimates of FFM when compared to the measurements by DXA (FFM_dxa = 35.80 kg versus FFM_deurenberg = 36.36 kg) and very close estimates of FM (FM_dxa = 9.16 kg and FM_deurenberg = 9.57 kg) The Kushner equation showed slightly better estimates for FM (FM_kushner = 9.0 kg) when compared to the DXA, but not for FFM. Sun equation gave the broadest differences for FM and FFM when compared with DXA.

Conclusion

The best available BIA equation to calculate the FFM and the FM in patients with AN is the Deurenberg equation. It takes into account the weight, height and age and is applicable in adults and adolescents AN patients with BMI of 12.8–21.0, and for ages between 13.4 and up to 36.9 years.     

Nutritional assessment: lean body mass depletion at hospital admission is associated with an increased length of stay

BACKGROUND: Low fat-free mass may be an independent risk factor for malnutrition that results in an increased length of hospital stay (LOS). OBJECTIVES: The objectives were to compare differences in fat-free mass and fat mass at hospital admission between patients and healthy control subjects and to determine the association between these differences and the LOS. DESIGN: Patients (525 men, 470 women) were prospectively recruited at hospital admission. Height-corrected fat-free mass and fat mass (fat-free-mass index or fat-mass index; in kg/m2) were determined in patients at admission by bioelectrical impedance analysis and were compared with values for sex-, age-, and height-matched control subjects. Patients were classified as well-nourished, moderately depleted, or severely depleted on the basis of a Subjective Global Assessment questionnaire and a body mass index (in kg/m2) < or > 20. RESULTS: Low fat-free mass was noted in 37% and 55.6% of patients hospitalized 1-2 d and > 12 d, respectively. The odds ratios were significant for fat-free-mass index and were higher in patients with a LOS of > 12 d [men (odds ratio: 5.6; 95% CI: 3.1, 10.4), women (4.4; 2.3, 8.7)] than in those with a LOS of 1-2 d [men (3.3; 2.2, 5.0), women (2.2; 1.6, 3.1)]. Severe nutritional depletion was significantly associated only with a LOS > 12 d. CONCLUSION: Fat-free mass and fat-free-mass index were significantly lower in patients than in control subjects. Because the fat-free-mass index is significantly associated with an increased LOS, provides nutritional assessment information that complements that from a Subjective Global Assessment questionnaire, and is a more sensitive determinant of the association of fat-free mass with LOS than is a weight loss > 10% or a body mass index < 20, it should be used to evaluate nutritional status.     

Place de l'impédancemétrie dans le dépistage de la dénutrition à l'hôpitalBio-impedance analysis: Screening of denutrition in hospitalized patients

The prevalence of malnutrition is high in patients and tends to worsen during the hospital stay. In the absence of one reliable method to evaluate patients, the assessment of nutritional status is based on a global approach. Body composition measurement by bio-impedance analysis (BIA) is one of these approaches. Body composition measurements can detect malnutrition or abnormal hydration. Fat free mass, fat mass, and total body water are the main body compartments that are evaluated. Determination of abnormal body composition can then guide nutritional support. The reliability of BIA depends on the equation used to predict body composition and the parameters included in the formula (weight, height, sex, age, race, etc.). These parameters allow to minimize measurement errors. Thus, formula developed for specific populations allow to evaluate the nutritional status with reasonable error rates. BIA has been found to be inaccurate with abnormal distribution of body compartments (ascites, dialysis, lypodystrophy, etc.) or extreme weights (cachexia, obesity). Multi-frequency or segmental BIA was developed to overcome hydration abnormalities and variations in body geometry. However, these techniques require further validation. The BIA seems to have some limitations. This review aims to assess the reliability of BIA to detect protein-calorie malnutrition at hospital admission or during nutritional follow-up of patients.     

Place de l'impédancemétrie dans le dépistage de la dénutrition à l'hôpital

The prevalence of malnutrition is high in patients and tends to worsen during the hospital stay. In the absence of one reliable method to evaluate patients, the assessment of nutritional status is based on a global approach. Body composition measurement by bio-impedance analysis (BIA) is one of these approaches. Body composition measurements can detect malnutrition or abnormal hydration. Fat free mass, fat mass, and total body water are the main body compartments that are evaluated. Determination of abnormal body composition can then guide nutritional support. The reliability of BIA depends on the equation used to predict body composition and the parameters included in the formula (weight, height, sex, age, race, etc.). These parameters allow to minimize measurement errors. Thus, formula developed for specific populations allow to evaluate the nutritional status with reasonable error rates. BIA has been found to be inaccurate with abnormal distribution of body compartments (ascites, dialysis, lypodystrophy, etc.) or extreme weights (cachexia, obesity). Multi-frequency or segmental BIA was developed to overcome hydration abnormalities and variations in body geometry. However, these techniques require further validation. The BIA seems to have some limitations. This review aims to assess the reliability of BIA to detect protein-calorie malnutrition at hospital admission or during nutritional follow-up of patients.     

Validation of dual x-ray absorptiometry for body-composition assessment of rats exposed to dietary stressors.

Evidence of the validity and accuracy of dual x-ray absorptiometry (DXA) to measure soft-tissue composition of laboratory rats with altered body composition associated with nutritional perturbations is lacking. We compared DXA determinations made in prone and supine positions with measurements of chemical composition of 49 male, weanling Sprague-Dawley rats that were fed the basal AIN-93 growth diet, were fed the basal diet modified to contain 30% fat, were fasted for 2 d, were limit fed 6 g of the basal diet daily for 1 wk, or were treated with furosemide (10 mg/kg intraperitoneally 2 h before DXA). DXA produced similar estimates of body mass and soft-tissue composition in the prone and supine positions. DXA estimates of body composition were significantly correlated with reference composition values (R(2) = 0.371-0.999). DXA discriminated treatment effects on body mass, fat-free and bone-free mass, fat mass, and body fatness; it significantly underestimated body mass (1% to 2%) and fat-free and bone-free mass (3%) and significantly overestimated fat mass and body fatness (3% to 25%). The greatest errors occurred in treatment groups in which body mass was diminished and body hydration was decreased. These findings suggest that DXA can determine small changes in fat-free, bone-free mass in response to obesity and weight loss. Errors in DXA determination of fat mass and body fatness associated with extra corporeal fluid and dehydration indicate the need for revision of calculation algorithms for soft-tissue determination.     

Reference values of fat-free and fat masses by bioelectrical impedance analysis in 3393 healthy subjects

Determination of fat-free mass (FFM) and fat mass (FM) is of considerable interest in the evaluation of nutritional status. In recent years, bioelectrical impedance analysis (BIA) has emerged as a simple, reproducible method used for the evaluation of FFM and FM, but the lack of reference values reduces its utility to evaluate nutritional status. The aim of this study was to determine reference values for FFM, FM, and %FM by BIA in a white population of healthy subjects, to observe the changes in these values with age, and to develop percentile distributions for these parameters. Whole-body resistance of 1838 healthy white men and 1555 women, aged 15-64 y, was determined by using four skin electrodes on the right hand and foot. FFM and FM were calculated according to formulas validated for the subject groups and analyzed for age decades. This is the first study to present BIA-determined age- and sex-specific percentiles for FFM, FM, and %FM for healthy subjects, aged 15-64 y. Mean FM and %FM increased progressively in men and after age 45 y in women. The results suggest that any weight gain noted with age is due to a gain in FM. In conclusion, the data presented as percentiles can serve as reference to evaluate the normality of body composition of healthy and ill subject groups at a given age.     

Reliable bioelectrical impedance analysis estimate of fat-free mass in liver, lung, and heart transplant patients

BACKGROUND: Bioelectrical impedance analysis (BIA) can be valuable in evaluating the fat-free (FFM) and fat masses (FM) in patients, provided that the BIA equation is valid in the subjects studied. The purpose of the clinical evaluation was to evaluate the applicability of a single BIA equation to predict FFM in pre- and posttransplant patients and to compare FFM and FM in transplant patients with healthy controls. METHODS: Pre- and posttransplant liver, lung, and heart patients (159 men, 86 women) were measured by two methods-50-kHz BIA-derived FFM (FFM(BIA)) by Xitron instrument and DXA-derived FFM (FFM(DXA)) by Hologic QDR-4500 instrument-and compared with healthy controls (196 men, 129 women), aged 20 to 79 years. RESULTS: The high correlation coefficient (r = .974), small bias (0.3 +/- 2.3 kg), and small SEE (2.3 kg) suggest that BIA using the GENEVA equation is able to predict FFM in pre- and posttransplant patients. The study shows that the lower weight seen in transplant men and women than in controls was due to lower FFM, which was partially offset by higher FM in men but not in women. Furthermore, the higher weights in posttransplant than in pretransplant patients were due to higher FM and % FM that was confirmed by lower FFM/FM ratio in posttransplant patients. CONCLUSIONS: Single 50-kHz frequency BIA permits measurement of FFM in pre- and posttransplant patients.     

Fat-Free Mass Index as a Surrogate Marker of Appendicular Skeletal Muscle Mass Index for Low Muscle Mass Screening in Sarcopenia

ObjectivesWe aimed to examine the relationship between the fat-free mass index (FFMI; FFM/height²) and appendicular skeletal muscle mass index (ASMI; ASM/height²), measured using both bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA), and investigate the effects of age and obesity. We also evaluated the suitability of BIA-measured FFMI as a simple surrogate marker of the ASMI and calculated the optimal FFMI cutoff value for low muscle mass screening to diagnose sarcopenia.DesignCross-sectional study.Setting and ParticipantsThis study included 1313 adults (women, 33.6%) aged 40-87 years (mean age, 55 ± 10 years) from the WASEDA’S Health Study.MethodsBody composition was measured using multifrequency BIA and DXA. Low muscle mass was defined according to the criteria of the Asian Working Group for Sarcopenia 2019.ResultsBIA-measured FFMI showed strong positive correlations with both BIA- (r = 0.96) and DXA-measured (r = 0.95) ASMIs. Similarly, in the subgroup analysis according to age and obesity, the FFMI was correlated with the ASMI. The areas under the receiver operating characteristic curve for screening low muscle mass defined by DXA-measured ASMI using BIA-measured FFMI values were 0.95 (95% CI 0.93-0.97) for men and 0.91 (95% CI 0.87-0.94) for women. The optimal BIA-measured FFMI cutoff values for screening low muscle mass defined by DXA-measured ASMI were 17.5 kg/m² (sensitivity 89%, specificity 88%) for men and 14.6 kg/m² (sensitivity 80%, specificity 86%) for women.Conclusions and ImplicationsThe FFMI showed a strong positive correlation with BIA- and DXA-measured ASMIs, regardless of age and obesity. The FFMI could be a useful simple surrogate marker of the ASMI for low muscle mass screening in sarcopenia in community settings. The suggested FFMI cutoff values for predicting low muscle mass are <18 kg/m² in men and <15 kg/m² in women.     

A low pretransplant peripheral blood mononuclear cell complex I activity predicts metabolic disturbances and inability to regain fat free mass in cirrhotic patients undergoing liver transplantation

Liver cirrhosis is associated with malnutrition and often, after liver transplantation, with the development of obesity and the inability to gain lean body mass. We have previously shown that peripheral blood mononuclear cell (PBMNC) complex I activity could be an appropriate marker for nutritional assessment. In this context, we hypothesized that a low pretransplant PBMNC complex I activity may predict a poor nutritional status in cirrhotic patients undergoing liver transplantation. Fifteen cirrhotic patients (CP) (8 men and 7 women) were recruited and investigated before and 4 months after liver transplantation. Body weight, body composition by DEXA, anthropometric measures (triceps skinfold thickness and midarm muscle circumference), resting energy expenditure, respiratory quotient and PBMNC complex I activity were measured on both time points. Patients were divided into 2 groups depending on their pretransplant PBMNC complex I activity (low vs high complex I activity [CP_{low CI} vs CP_{high CI}]), using as an arbitrary cutoff value—the mean complex I activity observed in age-matched healthy controls. Before transplantation, the CP_{low CI} group who showed a lower complex I activity (2.11 ± 0.53 vs 4.54 ± 0.98 nmol/min per milligram of protein, P < .01) was significantly younger (44 ± 9 vs 62 ± 8 years old, P < .01); no differences were observed for any other nutritional parameters when compared to the CP_{high CI} group. After transplantation, only the CP_{low CI} group demonstrated a significant increase of complex I activity (+77%, P < .01), respiratory quotient (+10.5%, P < .02), triceps skinfold thickness (+126%, P < .005), and a significant decrease of fat-free mass (−8%, P < .01). In summary, our findings indicate that a low pretransplant PBMNC complex I activity in cirrhotic patients could be a useful marker of poor nutritional status despite the lack of traditional indicators of malnutrition by predicting metabolic disturbances and an inability to regain fat-free mass after liver transplantation.