Related Experiment Video
Updated: Apr 11, 2026

Measurement of Tissue Oxygenation Using Near-Infrared Spectroscopy in Patients Undergoing Hemodialysis
Published on: October 2, 2020
Natremia, tonicity, and conductivity measurements in hemodialyzed patients
François Gaillard1, Sophie Laplanche, Thierry Petitclerc
1Hemodialysis Center, AURA, Paris - France.
Purpose:
Natremia is usually considered to reflect tonicity in non-hemodialyzed patients. Some hemodialysis monitors provide an online value (NaCond) of natremia calculated from conductivity measurements. This study compared the relation between tonicity and natremia (NaLab) measured at laboratory with the relation between tonicity and NaCond in hemodialysis patients.
Methods:
Fifty-five hemodialysis sessions performed with a Fresenius 5008 dialysis monitor (Fresenius Medical Care, Bad Homburg, Germany) providing a value of NaCond were analyzed. Tonicity (calculated as "osmolality - urea"), NaLab and NaCond were measured at the beginning and end of sessions.
Results:
The r2 correlation-coefficient between tonicity and NaLab is 0.48 (n = 110). The correlation between tonicity and NaCond is stronger (r2 = 0.71).
Conclusions:
Conductivity measurements provide a natremia value (NaCond) that is a better surrogate for tonicity than natremia measured at laboratory. Because NaCond is not obtained from sodium measurement, dialysis monitors should display a value for plasma conductivity (mS/cm) instead for natremia (mmol/l).
More Related Videos
07:38Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane
Published on: March 30, 2015
08:09Wastewater Irrigation Impacts on Soil Hydraulic Conductivity: Coupled Field Sampling and Laboratory Determination of Saturated Hydraulic Conductivity
Published on: August 19, 2018
Related Concept Videos
Hemodialysis III: Nursing Management
Hemodialysis II: Procedure and Complications
Dialysis
Dialysis
Acute kidney injury develops suddenly and can be caused by pre-renal causes (e.g., hypovolemia, shock), intrinsic renal causes (e.g., acute tubular necrosis), or post-renal causes (e.g., urinary obstruction). In contrast, chronic renal failure progresses gradually over time and is often...
Serum Studies: Renal Function Tests
Hemodialysis I: Introduction