Tetrapolar Bioelectrical Impedance Analysis Research Articles

Ultrasonographic Measurement of Intra-Abdominal Fat Thickness in HIV-Infected Patients Treated or Not with Antiretroviral Drugs and Its Correlation to Lipid and Glycemic Profiles

Aims: To compare the intra-abdominal fat thickness measured by ultrasound between HIV-infected patients treated or not with antiretroviral drugs and to correlate these visceral adiposity measurements to other parameters of cardiovascular risks. Methods: In a transversal observational study, 160 HIV-infected patients were recruited and divided in two groups, i.e., 123 antiretroviral (ARV)-treated and 37 ARV-naïve patients. These patients were submitted to anthropometric determinations, laboratorial analysis, ultrasonographic measurements of subcutaneous and intra- abdominal fat thickness and to tetrapolar bioelectrical impedance analysis in order to measure the body composition. Results: In the patients treated with highly active antiretroviral therapy (HAART) the intra-abdominal fat pad was significantly thicker than that of the untreated group (69 ± 21 mm, n = 123 vs. 60 ± 18 mm, n = 37; p = 0.03 Student’s t test). The intra-abdominal fat thickness correlated significantly with plasma triglyceride, total cholesterol, fasting glucose, glucose measurements 2 h after dextrose load, fasting insulin, HOMA-IR index, systolic and diastolic blood pressures, weight, BMI, WHR and caliper-measured total fat percentage. Conclusion: The results showed that antiretroviral therapy is associated with increased ultrasonographic measurements of visceral adiposity. Our data demonstrated a strong correlation between intra-abdominal fat thickness and independent risk factors of cardiovascular disease: atherogenic lipid profile and insulin resistance.

Single Frequency Bioelectrical Impedance is a Poor Method for Determining Fat Mass in Moderately Obese Women

The primary aim of weight loss intervention in obesity is the loss of fat mass (FM). Hence, determinations of changes in FM and fat free mass (FFM) during weight loss are of clinical value. The authors compared the clinical utility of SkinFold Thickness (SKF), tetrapolar bioelectrical impedance analysis (BIA) and a body mass index (BMI) based calculation, in determining changes in percentage of fat mass (delta%FM). Using dual X-ray absorptiometry (DEXA) measurements of %FM as a standard, BIA, SKF and BMI were compared in 41 moderately obese women (BMI 30-35) before and after significant weight loss (-13.9 +/- 5.8 kg). When measuring fat mass loss, SKF was precise and accurate with a bias of +0.86 +/- 6.16 %, while the BMI-based estimation had a systematic bias of +6.36 +/- 6.04 % (r2 = 0.791, P < 0.001). BIA using the Lukaski formula had a bias of +5.22 % and limits of agreement that approached the magnitude of the measurement (+/- 20.82 %), thus providing no information. In contrast, BIA using the Segal formula had a systematic bias of +7.81% (r2 = 0.636, P < 0.001) and gave narrower limits of agreement (+/- 8.34 %). For measuring changes in %FM with weight loss, BIA has no clinical value using the Lukaski formula, and using the Segal formula BIA provided no additional information to that given by BMI. We show that BIA instrument variables confound the estimates of %FM achieved by the BMI component of the Lukaski and Segal formulas.

Validity of the leg-to-leg bioimpedance to estimate changes in body fat during weight loss and regain in overweight women: a comparison with multi-compartment models

To investigate changes in body composition and the validity of the leg-to-leg bioimpedance (LTL) method to measure body fat during active weight loss (WL) and weight regain (WR). Longitudinal, 12-week weight loss intervention (3.3-3.8 MJ/day) and subsequent follow-up at 1 year. Fifty-eight adult women aged between 24 and 65 years (mean age: 46.8+/-8.9 years) and with a body mass index (BMI) > or =25 kg/m(2) (mean BMI: 31.6+/-2.5 kg/m(2), range=26.0-48.2 kg/m(2)) participated in the study. Fat mass (FM) was measured at baseline, 12 weeks, 24 weeks and 52 weeks using three- and four-compartment (4-C) models, air displacement plethysmography (ADP), deuterium dilution - total body water (TBW), dual-energy X-ray absorptiometry (DXA), skinfold thickness (SFT), tetrapolar bioelectrical impedance analysis (T-BIA) and LTL. At the end of the weight loss programme, subjects lost 9.9+/-3.5 kg weight (P<0.001) and 7.6+/-0.5 kg fat (P<0.001) but after 1 year they had regained 4.9+/-3.7 kg of weight and 3.7+/-2.9 kg of fat. The 4-C model showed that FM and TBW accounted for 76.2 and 23.6% of the loss in body mass and 81.8 and 17.7% of the tissue accrued during weight regain, respectively. The estimate of body fat change by LTL relative to multi-compartment models (WL(bias+/-2s.d.)=0.51+/-3.26 kg; WR(bias+/-2s.d.)=-0.25+/-2.30 kg) was similar to ADP, DXA and TBW in both phases but it was better than T-BIA (WL(bias+/-2s.d.)=0.17+/-7.90 kg; WR(bias+/-2s.d.)=-0.29+/-7.59 kg) and skinfold thickness (WL(bias+/-2s.d.)=2.68+/-6.68 kg; WR(bias+/-2s.d.)=-0.84+/-3.80 kg). Weight loss and regain were associated with minimal changes in lean tissue as measured using multi-compartment models. The LTL system is a useful method to measure body composition changes during clinical weight management programmes.

Comparison of Methods to Assess Body Composition Changes during a Period of Weight Loss

To assess the accuracy of body composition measurements by air displacement plethysmography and bioelectrical impedance analysis (BIA) compared with DXA during weight loss. Fifty-six healthy but overweight participants, 34 women and 22 men (age, 52 +/- 8.6 years; weight, 92.2 +/- 11.6 kg; BMI, 33.3 +/- 2.9 kg/m(2)) were studied in an outpatient setting before and after 6 months of weight loss (weight loss, 5.6 +/- 5.5 kg). Subjects were excluded if they had initiated a new drug therapy within 30 days of randomization, were in a weight loss program, or took a weight loss drug within 90 days of randomization. Subjects were randomly assigned either to a self-help program, consisting of two 20-minute sessions with a nutritionist and provision of printed materials and other self-help resources, or to attendance at meetings of a commercial program (Weight Watchers). Body composition was examined by each of the methods before and after weight loss. BIA (42.4 +/- 5.8%) underestimated percentage fat, whereas the BodPod (Siri = 51.7 +/- 6.9%; Brozek = 48.5 +/- 6.5%) overestimated percentage fat compared with DXA (46.1 +/- 7.9%) before weight loss. Correlation coefficients for detecting changes in body composition between DXA and the other methods were relatively high, with Brozek Deltafat mass (FM; r(2) = 0.63), Siri FM (r(2) = 0.65), tetrapolar BIA percentage fat (r(2) = 0.57), and Tanita FM (r(2) = 0.61) being the highest. In conclusion, all of the methods were relatively accurate for assessing body composition compared with DXA, although there were biases. Furthermore, each of the methods was sensitive enough to detect changes with weight loss.

Influence of hormonal status and oral intake on phase angle in HIV-infected men

Objective Phase angle α can be easily obtained from bioelectrical impedance analysis. In the literature, this angle is the single best predictor of survival in patients with the human immunodeficiency virus (HIV). The aim of our study was to detect nutritional and biochemical parameters that influence the phase angle. Methods One hundred men with HIV were studied. In all patients, anthropometric and biochemical nutritional evaluations were performed. Basal concentrations of testosterone and somatomedin C (insulin-like growth factor-1) were measured. Tetrapolar bioelectrical impedance analysis was used to determine body composition. All patients received instruction on keeping 24-h written food records. Albumin, prealbumin, transferrin, CD4 count, and total lymphocytes were measured. Results Patients' mean age was 39.1 ± 9.9 y, mean body weight was 66.8 ± 11.2 kg, and mean body mass index was 22.5 ± 3.5 kg/m 2. Patients' average fat-free mass was 58.05 ± 8.7 kg and average fat mass was 9.17 ± 4.9 kg. Average phase angle α was 8.21 ± 0.88 degrees. Patients were assigned to one of two groups according to phase angle: those with a phase angle α smaller than 8.2 degrees (group 1) and those with a phase angle α of at least 8.2 degrees (group 2). Weight, body mass index, transferrin, and somatomedin C were significantly higher in group 2 ( P < 0.05 for all). There were significant positive correlations between phase angle α and somatomedin C ( r = 0.3, P < 0.05) and protein intake ( r = 0.2, P < 0.05). In the multivariate analysis (adjusted for number of antiretroviral drugs prescribed, age, disease stage, and energy and protein intakes), only somatomedin C remained in the model ( F = 4.5, P < 0.05), with an increase in phase angle α of 0.56 degrees (95% confidence interval, 0.04 to 1.08) with each 1-nM/L increase in somatomedin C. Conclusion Somatomedin C and protein intake influenced phase angle α, but only somatomedin C remained as an independent factor in the multivariate analysis.

Contribution of genetic and environmental factors to variation in body compartments - a twin study in adults

This study aimed at analyzing the contribution of genetic and environmental factors on phenotypic variation of various traits of body composition. Subjects were 30 same-sexed pairs of twins including 20 monozygous (MZ) and 10 dizygous (DZ) pairs, aged 19-62 years. Zygosity was determined by DNA typing and morphological diagnosis. Body composition parameters (fat mass FM, lean body mass LBM, body cell mass BCM, extracellular mass ECM, total body water TBW, extracellular water ECW, and intracellular water ICW) were estimated by tetrapolar bioelectrical impedance analysis. Potential environmental factors influencing body composition (number of children, sporting activity and smoking behaviour) were determined by questionnaires. Heritabilities for traits of body composition were calculated by use of the twin method. Intraclass correlation is > 0.80 for the variation of LBM, BCM, ECM, TBW, ECW, and ICW in both MZ and DZ twins. Estimated heritability (h2) for FM, LBM, BCM, ECW, TBW, ECW, and ICW is 65%, 77%, 79%, 83%, 76%, 68%, and 82%, respectively. The h2 values for FM and LBM are consistent with those reported in other twin studies. For BCM, ECM, ECW and ICW, no comparative h2 estimates exist. Within-pair differences in body compartments do not change with increasing age in MZ and DZ twin pairs (p > 0.05). Stepwise multiple regression analyses indicate that zygosity, age, sex, number of children, sporting level and smoking behaviour do not significantly predict within-pair differences for weight, BMI, FM, LBM, TBW, ECW and ICW (each, p > 0.05). In contrast, sex and the number of children explain together 27% of observed within-pair differences for BCM. Zygosity is the only significant predictor of within-pair differences for ECM and height, explaining 20% (p = 0.008) and 36% of variance, respectively (p < 0.0001). Results indicate that genetic factors exert stronger influences on body composition than the considered environmental traits.

Somatic versus reproductive energy allocation in Papua New Guinea: life history theory and public health policy.

A fundamental evolutionary problem faced by organisms is how to allocate energy to somatic and reproductive functions in ways that optimize fitness. Given that energy is limited in all environments, energy allocation necessarily involves physiological tradeoffs between such factors as growth and reproduction, reproduction and condition, and current reproduction and future survival. Ultimately, the "decisions" that are made about energy allocation among growth, survival, and reproduction determine life history patterns and trajectories of organisms. For humans, knowing how energy allocation to reproduction will likely impact other aspects of the somatic well-being of individuals may also have practical implications for public health policy. This article reviews the evidence for energy tradeoffs between somatic and reproductive functioning in a range of human societies. It also seeks to corroborate the results of earlier work in Papua New Guinea on lactation-related maternal energy depletion using an independent measure of maternal energy reserves, tetrapolar bioelectrical impedance analysis. The current analysis shows that maternal energy reserves decline over the course of lactation and that a cumulative parity-specific decline in maternal energy reserves also exists. A longitudinal follow-up of five women over 11 years shows the decline to amount to about 3 mm of subcutaneous fat per round of pregnancy and lactation. The results corroborate predictions from life history theory and have applied public health implications. In particular, It is suggested that policies such as lactation advocacy that encourage enhanced energy allocation to reproduction in order to promote child health may have the unintended result of compromising maternal well-being, particularly in nations of the developing world. Consequently, it is recommended that nutritional support of mothers be implemented in concert with lactation promotion.

Assessing regional muscle mass with segmental measurements of bioelectrical impedance in obese women during weight loss.

Tetrapolar bioelectrical impedance analysis (BIA) offers the possibility of determining the bioconductor volume in discrete segments of the body, because the resistivities of bone, fat, and skeletal muscle differ considerably. We tested this hypothesis by measuring BIA and anthropometry of defined segments of the right thighs of women before and during a controlled weight-loss program. Eight women, aged 22 to 32 years, with a body mass index of 37.8 +/- 1.6 (mean +/- SE) kg/m2 underwent determinations of body composition with dual-energy X-ray absorptiometry (DXA) and regional BIA measurements (800 microA at 50 kHz) before the program, and monthly thereafter for four months during weight loss. BIA measurements were made with spot-detector electrodes positioned 10 cm apart on the anterior of the thigh, and source electrodes placed on the right hand and foot. The physical volume of the thigh segment decreased by 29 +/- 3% (p < 0.0001), with a modest change in its electrical volume (8 +/- 0.2%; p < 0.05) during weight loss. Muscle (181 +/- 49 g; p < 0.05) and fat mass (702 +/- 95 g; p < 0.001) also declined. The electrical or bioconductor volume correlated with DXA determinations of muscle mass (r = 0.91, p < 0.0001), whereas physical volume correlated with fat mass (r = 0.95, p < 0.0001). These findings support the hypothesis that BIA is a valid method to assess regional muscle mass in humans.

Fat distribution evaluated by computed tomography and metabolic abnormalities in patients undergoing antiretroviral therapy: preliminary results of the LIPOCO* study

Fat distribution abnormalities have been reported in patients treated with various antiretroviral drug regimens. The LIPOCO study is an ongoing observational study of unselected HIV-infected patients which aims to better characterize such disorders and their metabolic correlations. Cross-sectional analysis of data collected at baseline in the first 154 male patients included. Investigators divided patients into four predetermined clinical categories of fat distribution: lipoatrophy, obesity, mixed condition and normal. Body composition (tetrapolar bioelectrical impedance analysis and skinfold thickness), fat distribution [computed tomography (CT) scan], plasma glucose and insulin concentrations both fasting and during an oral glucose tolerance test and endocrine and lipid profile were measured and compared between the four groups. Patients in the lipoatrophy group had significantly decreased abdominal and mid-thigh subcutaneous fat area values and elevated levels of plasma triglycerides. Patients in the obese and mixed groups had significantly increased intra-abdominal fat area values and elevated levels of plasma insulin and C-peptide. The CT scans identified some patients with isolated subcutaneous fat accumulation but no other alterations in fat distribution and no insulin resistance. Visceral adipose tissue measured by CT scan was positively correlated with fasting insulin and the sum of insulin levels (P < 0.0001). Fasting insulin as well as the sum of insulin levels were negatively correlated with the delta HIV-RNA (log(10)). In a multivariate logistic regression model, the use of stavudine significantly correlated with fat wasting in both nucleoside reverse transcriptase inhibitor and protease inhibitor groups: odds ratio (OR), 413 [95% confidence interval (CI), 5.2-999; P = 0.0068] and OR, 2.08 (95% CI, 0.92-7.0; P = 0.058) respectively, when compared with the use of zidovudine. Neither lamivudine or didanosine use, nor the use of protease inhibitors were significantly associated with fat distribution abnormalities or fat wasting. These preliminary results suggest that three major types of fat distribution abnormalities may occur in isolation or in association in HIV-infected patients undergoing active antiretroviral therapy: a fat depletion or 'lipoatrophy' syndrome which might be related to the use of stavudine; a mixed or fat redistribution syndrome related to an unusual side-product of effective virus control; and a subcutaneous adiposity syndrome reflecting increase in caloric intake.

Bioelectric impedance analysis: Experience with male patients with cirrhosis

Bioelectric impedance analysis is a new, convenient and portable method used to estimate total body water and to assess body composition in healthy people. We used the tetrapolar bioelectrical impedance analysis method in 58 cirrhotic patients to assess its clinical applicability. Whole-body resistance, reactance and impedance were measured and compared with those of 30 healthy volunteers matched for age and sex. The resistance and impedance values of ascitic cirrhotic patients (resistance = 461 ± 80Ω; impedance = 462 ± 80 Ω) and nonascitic cirrhotic patients (resistance = 487 ± 96 Ω; impedance = 489 ± 97 Ω) were comparable with the resistance (488 ± 44 Ω) and impedance (491 ± 44 Ω) of controls. However, a significant (p < 0.05) reduction in whole body reactance was found in patients with ascites and in those without ascites (34 ± 9 Ω vs. 47 ± 12 Ω) as compared with healthy subjects (56 ± 7 Ω). In 10 ascitic patients total body water was determined both before and after paracentesis; the volume of intraperitoneal fluid removed (7.9 ± 3.8 L) could not be fully accounted for but only detected as an average volume of 1.9 ± 1.0 L independently of the initial volume of the ascites. Our data clearly demonstrate that tetrapolar bioelectric impedance analysis is not adequate for measuring variations of “compartmentalized” fluid in the abdomen. (HEPATOLOGY 1991;13:892–895.)

Bioelectric impedance analysis: Experience with male patients with cirrhosis

Bioelectric impedance analysis is a new, convenient and portable method used to estimate total body water and to assess body composition in healthy people. We used the tetrapolar bioelectrical impedance analysis method in 58 cirrhotic patients to assess its clinical applicability. Whole-body resistance, reactance and impedance were measured and compared with those of 30 healthy volunteers matched for age and sex. The resistance and impedance values of ascitic cirrhotic patients (resistance = 461 +/- 80 omega; impedance = 462 +/- 80 omega) and nonascitic cirrhotic patients (resistance = 487 +/- 96 omega; impedance = 489 +/- 97 omega) were comparable with the resistance (488 +/- 44 omega) and impedance (491 +/- 44 omega) of controls. However, a significant (p less than 0.05) reduction in whole body reactance was found in patients with ascites and in those without ascites (34 +/- 9 omega vs. 47 +/- 12 omega) as compared with healthy subjects (56 +/- 7 omega). In 10 ascitic patients total body water was determined both before and after paracentesis; the volume of intraperitoneal fluid removed (7.9 +/- 3.8 L) could not be fully accounted for but only detected as an average volume of 1.9 +/- 1.0 L independently of the initial volume of the ascites. Our data clearly demonstrate that tetrapolar bioelectric impedance analysis is not adequate for measuring variations of "compartmentalized" fluid in the abdomen.