Bioelectrical Impedance Phase Angle: Utility in clinical practice

The choice of the best nutrition assessment method in hospitalized patients remains a challenge. The aim of this study was to review the use of phase angle (PA) in clinical practice. PA is a parameter obtained from bioelectrical impedance analysis, being a derived measure from the relationship between resistance and reactance. Because PA is dependent on body cell mass (BCM) and cell membrane functions, it has been considered a prognostic marker in several clinical conditions. BCM reflects the cellular components responsible for energy transfer and biochemical activity and is considered an excellent reference for expressing the rates of physiological processes, such as energy expenditure and proteolysis. Low PA values suggest cell death or decreased cell integrity, whereas higher PA values suggest a large amount of intact cell membranes, with a consequently better prognosis. The literature lacks studies determining PA reference values, which has prevented its use in routine clinical practice. Reference values are therefore necessary to properly evaluate possible deviations from the population mean.