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Abstract: SA-PO354

Is Interdialytic Weight Gain Really All Fluid? A Longitudinal Study on Short Term Variability of Bioimpedance-Derived Normohydration Weight in Hemodialysis Patients

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis


  • Waller, Maximilian, Klinik Favoriten, Wien, Wien, Austria
  • Krenn, Simon, Austrian Institute of Technology GmbH, Wien, Wien, Austria
  • Mussnig, Sebastian, Medizinische Universitat Wien, Wien, Wien, Austria
  • Hecking, Manfred, Medizinische Universitat Wien, Wien, Wien, Austria

Group or Team Name

  • HD Research & Co.

Hemodialysis (HD) aims at reaching normohydration. The patient’s weight measured predialysis and the desired target weight postdialysis usually determine the ultrafiltration volume, following the assumption that weight gain from the previous HD session (IDWG) consists of excess fluid.


Longitudinal boimpedance spectroscopy (BIS) measurements with the Body Composition Monitor (BCM, Fresenius Medical Care Germany, v3.2) were obtained predialysis in 14 consecutive HD-sessions from 25 patients treated at the Chronic Hemodialysis Unit of Vienna General Hospital between October and December 2021. Short term variability of BIS derived parameters of fluid status was analyzed in an explorative fashion.


The normohydration weight was 78.4±13.9 kg on average ± standard deviation (SD) and varied longitudinally for each patient, with the intra-patient SD ranging from 0.36 to 2.24kg (average: 0.8 kg). When the predialysis weight increased from one HD session to the next, the normohydration weight increased also, indicating that the patient had not only gained fluid (Figure 1).


Under the assumption that the BCM yields adequate results, and even if the target weight was set to perfect normohydration with 0L fluid overload remaining postdialysis, any weight gain above the previous predialysis weight will likely not consist of fluid alone. These results suggest that the target weight should not be fixed.

Figure 1