From Isonatric to Isotonic Hemodialysis

<b><i>Background:</i></b> 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 (Na_Cond) and the other based on natremia measured at laboratory (Na_Lab). We compared the control of tonicity obtained by isonatric hemodialysis based on Na_Lab or Na_Cond. <b><i>Methods:</i></b> Changes in tonicity Na_Lab and Na_Cond 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 &#x3c;2 mOsm/kg); hypertonic sessions (tonicity increase ≥2 mOsm/kg). <b><i>Results:</i></b> During isotonic hemodialysis, Na_Cond decreases significantly by 1 mmol/L, whereas Na_Lab remained stable. <b><i>Conclusions:</i></b> Isonatric hemodialysis based on Na_Lab and isonatric hemodialysis based on Na_Cond is to be distinguished. Isotonic hemodialysis could be performed by decreasing Na_Cond by 1 mmol/L or maintaining Na_Lab stability.