Reliable bioelectrical impedance analysis estimate of fat-free mass in liver, lung, and heart transplant patients

Background: Bioelectrical. impedance analysis (BIA) can be valuable in eval uating the fat-free (FFM) and fat masses (FM) in patients, provided that th e BIA equation is valid in the subjects studied. The purpose of the clinica l evaluation was to evaluate the applicability of a single BIA equation to predict FFM in pre- and posttransplant patients and to compare FFM and FM i n transplant patients with healthy controls. Methods: Pre- and posttranspla nt liver, lung, and heart-patients (159 men, 86 women) were measured by two methods-50kHz BIA-derived FFM (FFMBIA) by Xitron instrument and DXA-derive d FFM (FFMDXA) by Hologic QDR-4500 instrument-and compared with healthy con trols (196 men, 129 women), aged 20 to 79 years. Results: The high correlat ion coefficient (r =.974), small bias (0.3 +/- 2.3 kg), and small SEE (2.3 kg) suggest that BIA using the GENEVA equation is able to predict FFM in pr e- and posttransplant patients. The study shows that the lower weight seen in transplant men and women than in controls was due to lower FFM, which wa s partially offset by higher FM in men but not in women. Furthermore, the h igher weights in posttransplant than in pretransplant patients were due to higher FM and % FM that was confirmed by lower FFM/FM ratio in posttranspla nt patients. Conclusions: Single 50-kHz frequency BIA permits measurement o f FFM in pre- and posttransplant patients.