Bioelectrical impedance analysis in medicine

The analysis of electrical bioimpedance (BIA) is a non-invasive, low cost and a commonly used approach for body composition measurement and assessment of clinical condition. There are a variety of methods applied for interpretation of measured bioimpedance data and a wide range of utilizations of bioimpedance in body composition estimation and evalution of clinical status. Bioelectrical impedance analysis is based on knowledge about the electrical properties of human body. The clues are provided here by elementary knowledge of the tissue and cellular structure of the organism and the basis of physics. The amount of electrical resistance (resistance) of a uniform object is directly proportional to its length (L) and specific resistance (ρ), and inversely proportional to its cross-sectional area (A). The impedance (Z) is a function of the mentioned resistance and reactance (XC), which in turn is inversely proportional to the frequency of the current and the electrical capacity of the system. BIA method can provide a reliable, safe and effective way to study body composition, as well as other parameters resulting from the distribution of water in the body. It can be used in the examination of body composition in both cases: healthy and chronic patients, with particular emphasis on diseases related to metabolism.