[Values of the phase angle by bioelectrical impedance; nutritional status and prognostic value]

Phase angle (PA) is the most established parameter from bioelectrical impedance analysis (BIA) for diagnosis of malnutrition and clinical prognosis, both associated with changes on cellular membrane integrity and alterations on fluids balance. PA expresses changes in quantity and quality of soft tissue mass (ie, cell membrane permeability and soft tissue hydration). A large body of clinical trials propose PA as a useful prognostic marker in clinical conditions like liver cirrhosis and breast, colon, pancreatic and lung cancer; positive association between PA and survival was also observed in surgical and HIV infected patients. Several authors suggest that PA can be an important tool in the evaluation of the clinical result or of the progression of the disease, and it can even be superior to other nutritional, biochemical or anthropometric indicators. Lack of reference values has limited its use in clinical and epidemiological situations. The purpose of this review is to describe PA reference values according to different clinical conditions as proposed in published scientific works.