Aim: To determine the validity and clinical safety of body compositon under the condition of acute fluid loss using bioelectrical impedance analysis (BIA).

Material and Method: Total of 24 hemodialysis patients’ body composition were measured and analysed before and after dialysis using foot-to-foot BIA. Pearson correlation analysis and paired t-test were used to analyse data and P<0.05 accepted as a significant.

Results: The mean (±SE) body weight reduction after dialysis was 2.15±0.2 kg, (%3.77, P=0.0001). Body fat mass changed between -0.7 to 1.3 kg among the patients (mean 2.15% increased, P=0.02). There were 3 different conditions in body fat mass: it decreased in 6 patients (25%), it did not change in 4 patients (16.7%) and it increased in 14 patients (58.3%). There was a negative lineer correlation between body water and fat mass (r = - 0.516, P< 0.009).

Conclusion: BIA can be affected by body water content and results inaccurate estimation. Erroneous in body composition estimation using BIA methods should be considered before having a clinical desicion on patients with obesity, cardiac problems and hemodialysis, which body content has a vital effects. Importantly the results were supported by other methods. ©2005, Fırat Üniversitesi, Tıp Fakültesi