From Isonatric to Isotonic Hemodialysis

Isonatric hemodialysis aims at maintaining stable cellular hydration through a close control of natremia, considered a surrogate of tonicity. However, 2 methods are available to perform isonatric hemodialysis: one based on natremia derived from plasma conductivity (NaCond) and the other based on natremia measured at laboratory (NaLab). We compared the control of tonicity obtained by isonatric hemodialysis based on NaLab or NaCond.

Changes in tonicity NaLab and NaCond were recorded during 55 hemodialysis sessions. Sessions were divided according to the variation of tonicity: hypotonic sessions (tonicity decrease ≥2 mOsm/kg); isotonic sessions (tonicity variation <2 mOsm/kg); hypertonic sessions (tonicity increase ≥2 mOsm/kg).

During isotonic hemodialysis, NaCond decreases significantly by 1 mmol/L, whereas NaLab remained stable.

Isonatric hemodialysis based on NaLab and isonatric hemodialysis based on NaCond is to be distinguished. Isotonic hemodialysis could be performed by decreasing NaCond by 1 mmol/L or maintaining NaLab stability.