APPLICATION OF IMPEDANCE IN THE DIAGNOSIS OF SARCOPENIA

Bioelectrical impedance analysis (BIA) is a simple, fast, cheap, cost-efficient, safe, non-invasive, harmless method that does not require patient collaboration. In addition, it is considered a good alternative to DXA for the body composition analysis, so it is increasingly used in clinical practice. There are two main BIA modalities: conventional or traditional BIA and bioelectrical impedance vector analysis (BIVA). The first is based on a two-compartment model of body composition, and requires the use of validated predictive equations developed in populations with clinical and biological characteristics similar to the study population (sex, age, race, physiological situation, pathology, etc.). This requirement is especially important in the elderly, given the changes that occur with age. Sometimes the lack of reference standards (and cut-off points) age and sex specific for the geriatric population makes it difficult to interpret the results. This modality has also been used to develop predictive equations for estimating skeletal muscle mass and appendicular skeletal muscle mass, two indicators used in the diagnosis of sarcopenia. BIVA is a semi-quantitative analysis method which allows to evaluate body cell mass (BCM) and hydration status. Several studies have shown in geriatric population a significant association between the results obtained with BIVA and conventional BIA and other nutritional indicators, such as the Mini-Nutritional Assessment (MNA) and the Subjective Global Assessment (SGA). Recent works propose the application of this technique for the identification and follow-up of sarcopenic individuals.