Phase Angle in Evaluating Nutritional Status

Güneş B. D. , Acar Tek N. , Akbulut G.

European Congress on Obesity (ECO2018), Vienna, Avusturya, 23 - 25 Mayıs 2018, ss.317

  • Basıldığı Şehir: Vienna
  • Basıldığı Ülke: Avusturya
  • Sayfa Sayıları: ss.317


Phase Angle in Evaluating Nutritional Status Deniz Güneş, B.; Acar Tek, N.; Akbulut, G. Nutrition and Dietetics, Gazi University, Ankara/Turkey Introduction: An accurate estimate of body composition is important in nutrition assessment and monitoring. Bioelectrical impedance analysis (BIA) is the most commonly used method for assessing body composition. BIA measures body component resistance (R, pure opposition of a biological conductor to alternating electric current) and reactance (Xc, capacitive resistance of cell membranes) by recording a voltage drop in applied current. Resistance is related to the water content in the tissues, while reactance is the resistive effect produced by the tissue interfaces and cell membranes. The phase angle (PhA) is calculated directly from R and Xc. This measure has a number of advantages, such as independence from regression equations, and the fact that it can be calculated even in situations in which it is not possible to estimate the body composition. Methods: Phase angle is more appropriate than impedance for the assessment of nutritional status, because PhA presents the degree of cellular health. In healthy persons, PhA ranges from 5° to 7°. In healthy subjects, age, sex and BMI are the major determinants of PhA. Ageing is associated 318 Obes Facts 2018;11(suppl 1):1–358 Abstracts with decline in tissue mass, which results in decreasing PhA. Males have higher PhA values due to higher muscle mass. Higher BMI is associated with more cells, which increases PhA until a BMI of 30 kg/m2 . Interestingly, at BMI >40 kg/m2 , an inverse relationship with PhA is observed. This has been attributed to increased tissue hydration or a pathological fluid overload. Low PhA indicates pathological membrane state and function. Low PhA may be due to over hydration and/or malnutrition. Accordingly, many studies find a correlation between phase angle and other measures of nutritional status and/or muscle mass. Results: Phase angle has gained popularity over the past years since it has shown to be highly predictive of impaired clinical outcome and mortality in a variety of diseases. PhA is frequently lower than normal in disease since influences such as infection, inflammation or disease-specific parameters may impair phase angle. Phase angle (PhA) is a predictor of morbidity and mortality in HIV/AIDS, pancreatic, colorectal, breast and lung cancer, liver cirrhosis, dialysis, pulmonary disease, amyotrophic lateral sclerosis, geriatric and surgical patients. Disease-related malnutrition is characterized by an early shift of fluids from intracellular water (ICW) to extracellular water (ECW) space with increased ECW/ICW and a concomitant decrease in body cell mass, both lowering phase angle. In patients suffering from malnutrition, PhA can reflect the early water shift from intracellular to extracellular space. Conclusion: In conclusion, together with the known biological determinants, malnutrition and inflammation have a strong impact on PhA in disease. Phase angle is a superior indicator of survival and outcome and should therefore be used as screening tool for identification of patients at risk because of impaired nutritional or functional status.