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Abstract: TH-PO190

Relationship Between Interdialytic Weight Gain and Change in Whole Body Extracellular Resistance

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis


  • Zhu, Fansan, Renal Research Institute , New York, New York, United States
  • Kotanko, Peter, Renal Research Institute , New York, New York, United States
  • Levin, Nathan W., Icahn School of Medicine at Mount Sinai, New York, New York, United States

Estimation of interdialytic fluid gain is essential to determine ultrafiltration volume (UFV) in routine hemodialysis (HD). The aim of this study was to evaluate the relation between interdialytic changes in whole body extracellular resistance (Re) and interdialytic weight gain (WG) to facilitate prescription of ultrafiltration volumes (UFV) and rate (UFR) .


Ambulant patients were studied at ≥4 successive HD sessions. Whole body and calf bioimpedance were measured pre- and post-HD to obtain whole body extracellular resistance (Re) and calf normalized resistivity (CNR). Interdialytic weight change (ΔWt), change in Re (ΔRe), and CNR (ΔCNR) between pre- and post-HD (calculated as pre-HD minus post-HD of the preceding HD session), UFV, and UFR were recorded per HD session. Simple and multiple regression analysis were used to determine the relationship between ΔWt and ΔRe.


Thirty-eight patients (age 54.3±14 years, 17 females, BMI 26.4±7.4 kg/m2) were studied. We collected 387 measurements (10.2±6 per patient; table 1). UFV and UFR were 2.98±0.9 L and 0.78±0.24 L/h, respectively. ΔWt correlated inversely with ΔRe (average R2=0.71; range 0.44 to 0.91) with a slope of -53.3 (range -182 to -18) kg/Ω and an intercept of -12.9 (range -110 to 99) kg. As an example, Fig 1 and 2 show the relationship between ΔRe to ΔWt and to ΔECV in the same patient. Multiple regression analysis indicated that the slope was determined by UFR (p<0.01) and pre-HD CNR (p<0.05).


This study demonstrates that interdialytic weight gain can be predicted in individuals by whole body extracellular resistance. This method may be useful in patients who cannot be weighed. Using ΔRe to predict fluid gain is based on the high correlation between extracellular resistance and extracellular volume. Once corroborated in an elderly, non-ambulant population, this method may provide guidance for UFV prescription, a problem encountered occasionally in patients undergoing dialysis at home or – more frequently - in nursing homes.