Total body water and fat-free mass: evaluation of equations based on bioelectrical impedance analysis in infants and young children in India

Abstract

The association of early postnatal growth with diseases in adults such as hypertension, type 2 diabetes and CHD has generated interest in studying postnatal growth. Bioelectrical impedance analysis (BIA) is a useful measure to estimate total body water (TBW) and fat-free mass (FFM). We evaluated three published equations (Fjeld et al. (Pediatr Res (1990) 27, 98 -102), Bocage (MSc Thesis (1988) University of West Indies) and Kushner et al. (Am J Clin Nutr (1992) 56, 835 -839) to measure TBW and derived FFM based on BIA, using 2 H 2 O dilution as a reference method for suitability in infants in India. In a cross-sectional study in seventy-eight apparently healthy infants aged 6 -24 months from the urban poor attending an immunisation clinic at a hospital in Kolkata, we measured their length to the nearest 0·1 cm, weight to the nearest 10 g, resistance at 50 kHz using BIA and TBW using 2 H 2 O dilution. TBW was derived using three published BIA-based equations and compared with TBW using 2 H 2 O dilution. Based on the BIA equations of Fjeld et al., Bocage and Kushner et al., the mean TBW values were 2·46 % (P, 0·001), 4·62 % (P,0·001) and 9·50 % (P,0·001) lower than the reference 2 H 2 O method, respectively. All three published BIA-based equations consistently underestimated the TBW and FFM and appeared inadequate for studying infants in India. The equation described by Fjeld et al. gave the smallest deviation from the reference method and may be used for field studies. New equations based on population-specific data are desirable for a more precise measure of TBW. Practical methods for use in clinics and in the field to measure fat-free mass (FFM) or lean body mass in infants and children are largely based on anthropometry (such as height or length and weight) and recently introduced bioelectrical impedance analysis (BIA) techniques. Based on these methods, equations have been developed for children in both developed and developing countries. We could identify two equations (1,2) based on length or height and weight and three based on the BIA technique (Fjeld et al. , Bocage (4) and Kushner et al.( 5) ) for infants and children. Before we can use any of these equations with confidence on a population different from those on whom these equations were developed, it is important to validate them.We have earlier reported our evaluation of the two equations above based on length or height and weight using stable-isotope ( 2 H 2 O) dilution as the reference method (6) . However, equations based on conventional anthropometry, i.e. length and weight, have the inherent limitation in that they do not critically distinguish between FFM and fat mass. On the other hand, the theoretical basis of bioelectrical impedance analysis indicates that it is well suited to assess total body water (TBW) (7) . The method is based on the phenomenon that only water (containing electrolytes) in the human body can conduct electricity. Fat is relatively devoid of water and restricts the flow of current through it. At any given current freque...

Body composition assessment in the infant

“…For these and other reasons, BIA body composition equations tend to have poor performance across different ethnic groups and populations (Dehghan and Merchant, 2008), including in infants (Tanabe et al, 2012). For instance, FM and percent FM from total body electrical conductivity (TOBEC), a whole-body variant of BIA no longer commercially available (Hashimoto et al, 2002), and from BIA using existing equations (Sen et al, 2010) had poor correlation with estimates from isotope dilution. In both preterm (Dung et al, 2007) and term (Hashimoto et al, 2002; Lingwood et al, 2012) infants, BIA improves the prediction of FFM and percent body fat only very slightly, if at all, beyond simple anthropometrics (weight and length).…”

Bioelectrical impedance analysis for assessment of body composition in infants and young children‐A systematic literature review

“…One study, by Kushner et al, 17 involved pooled data from four varying datasets, thus the age of participants included ranged from birth to 67 years. Among other notable characteristics, four studies included preterm infants, [18][19][20][21] five included participants with varying levels of malnutrition, [22][23][24][25][26] and three included predominantly term infants. [27][28][29]…”

“…Seven used a SFBIA device, [17][18][19][20][21]25,26 five studies used a device capable of multi-frequencies, [22][23][24]29,30 and three studies used a device capable of spectroscopy. 27,28,31 However, among the studies which used MFBIA or BIS, most used data obtained at a single frequency (50 kHz) in their analyses.…”

“…27,28,31 However, among the studies which used MFBIA or BIS, most used data obtained at a single frequency (50 kHz) in their analyses. [22][23][24]28,29…”

Resonant cavity perturbation: a promising new method for the assessment of total body water in children

“…Hence, the trunk has only a small contribution to whole body impedance (Fuller et al, 2002) and will be insensitive to fluid changes (Woodrow et al, 1996). Numerous studies have reported large discrepancies between BIA and TBWdil in children (Sen et al, 2010;Bell et al, 2013;Montugnese et al, 2013).…”