BIS measurement was performed in each of the participants enrolled in the study by a specific member of staff who had completed a training course in the BIS technique, using a portable whole body bioimpedance spectroscopy device, the body composition monitor (BCM: Fresenius Medical Care, Bad Homburg, Germany). The BCM measures the impedance spectroscopy at 50 different frequencies between 5 kHz and 1 megahertz (MHz). Measurements were taken on the midweek dialysis session before the start of the hemodialysis treatment with the patient calm, supine, and relaxed in the dialysis bed for 10 minutes. Specific exclusion criteria were dictated by the device and included history of a pacemaker, defibrillator, metallic sutures, or stent implantation and amputation of a major limb. The device expresses the body weight in terms of lean tissue mass (LTM - mainly muscle), adipose tissue mass (ATM - mainly fat) and overhydration(OH). Each of these compartments has a specific composition and contains a known quantity of water per mass of tissue. Overhydration(OH) is almost 100% extracellular water, whereas the water of LTM and ATM consist of differing proportion of extracellular and intracellular water in addition to solid components.