Abstract: SA-PO746

Routine Hemodialysis Does Not Result in Optimal Plasma Magnesium Concentrations

Session Information

Category: Dialysis

  • 601 Standard Hemodialysis for ESRD

Authors

  • Leenders, Niki H.j., VU University Medical Center, Amsterdam, Netherlands
  • Hoekstra, Tiny, VU University Medical Center, Amsterdam, Netherlands
  • van Ittersum, Frans J., VU University Medical Center, Amsterdam, Netherlands
  • Hoenderop, Joost, Radboud university medical center, Nijmegen, Netherlands
  • Vervloet, Marc G., VU University Medical Center, Amsterdam, Netherlands
Background

Lower plasma magnesium (Mg) concentrations have been associated with a higher overall and cardiovascular mortality in hemodialysis patients. The optimal level of plasma Mg in hemodialysis patients appears to be above the reference range for the healthy population (typically 0.70-1.00 mmol/L). Plasma Mg is not routinely measured after hemodialysis. Aim of this study was to determine the effect of standard hemodialysis treatment on plasma Mg.

Methods

Plasma Mg was measured in duplicate before (Mgpre) and after (Mgpost) 6 consecutive dialysis sessions in 34 patients on a regular 3 times weekly hemodialysis schedule with a standard 0.50 mmol/L dialysate magnesium concentration.

Results

Mean Mgpre was 0.88 mmol/L (SD 0.14), 76% of patients had a mean Mgpre below 1.00 and the coefficient of intra-individual biological variation was 5.6%. Post-dialysis, mean Mg was decreased to 0.78 (SD 0.06, p<0.001).
Univariate linear regression showed that mean Mgpre and Mgpost in an individual were positively correlated (p<0.001) and the regression line indicated that Mg was stable during dialysis at a Mgpre of 0.73, decreased at a Mgpre above 0.73 and increased at a Mgpre below 0.73.
In an analysis with linear mixed models a 0.10 mmol/L higher Mgpre was associated with a 0.03 mmol/L higher Mgpost (95%-CI 0.024-0.037, p<0.001). If added to the model, baseline factors including gender, age, serum albumin, height and weight; and dialysis characteristics including vascular access type, dialysis duration, ultrafiltration volume, blood flow and dialysis efficiency did not change this association.

Conclusion

In the majority of the hemodialysis patients Mgpre is suboptimal. Routine hemodialysis further declines magnesium in the majority of patients. Current dialysate magnesium concentrations may be too low.

Funding

  • Private Foundation Support