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Abstract: FR-PO764

Changes in Serum Magnesium During Hemodialysis in Three Facility Settings

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis


  • Lacson, Eduardo K., Tufts University School of Medicine, Boston, Massachusetts, United States
  • Aweh, Gideon N., Dialysis Clinic, Inc., Nashville, Tennessee, United States
  • Bergeaux, Dwayne J., DCI, Crowley, Louisiana, United States
  • Fontenot, Deana, Dialysis Clinic Inc., Nashville, Tennessee, United States
  • Putatunda, Bhabendra, Nephrology Associates PC, Murfreesboro, Tennessee, United States
  • Wadhwa, Nand K., Stony Brook Medicine, Stony Brook, NY, East Setauket, New York, United States

A quality improvement project monitored serial serum magnesium (sMg) after a manufacturer changed dialysate magnesium (dMg) content. Three Medical Directors decided to order facility-wide post-dialysis sMg in addition to pre-dialysis sMg. Only 60-75% of sMg diffuse during hemodialysis (HD) due to sequestration by albumin a.k.a. the Gibbs-Donnan effect.


All maintenance HD patients in three outpatient units were included and sMg were tested with the monthly blood draws for December, 2017. Facility A utilized a dMg of 1.0 mEq/L which is most commonly used by DCI, a non-profit dialysis provider. Facility B also utilized dMg of 1.0 mEq/L but routinely gave oral magnesium supplements to target pre-dialysis sMg of ~2.0 mEq/L. Facility C utilized a dMg of 1.6 mEq/L with a citrate-based bath for over three years.


The facilities (A-B-C) had varying levels of pre-dialysis sMg with A having levels consistent with other DCI facilities at ~1.8 mEq/L.; B had higher pre-dialysis sMg of ~2.0 mEq/L consistent with its target; and C also had elevated pre-dialysis sMg consistent with prior reports at dMg ~1.5 mEq/L. At dMg = 1.0 mEq/L A (representing usual care) had ~10% decline of sMg post-dialysis compared to ~17% decline in B, which started with higher pre-dialysis sMg. The sMg was unchanged in C with no net removal at dMg of 1.6 mEq/L. Results are summarized in the table.


Serum magnesium did not fully equilibrate with dialysate consistent with the Gibbs-Donnan effect. Net sMg removal increases with higher sMg levels at dMg of 1.0 mEq/L; At dMg of 1.6 mEq/L, sMg is maintained at ~2.1 to 2.2 mEq/L with no net dialytic magnesium removal. These findings illustrate what could be expected in a comparative effectiveness study comparing dMg at 1.0 vs. 1.5 mEq/L.

Pre- & Post-HD Magnesium Under 3 Different Settings
FacilityDialysate MgOral Mg SupplementNPre-HD MgPost-HD Mg% Change
A1.0 mEq/LNo521.79 ± 0.25 1.61 ± 0.10-10%
B1.0 mEq/LYes1312.07 ± 0.27 1.71 ± 0.12-17%
C1.6 mEq/LNo422.15 ± 0.31 2.15 ± 0.190%

Mg = Magnesium; Note: Pre-HD & Post-HD serum magnesium shown as mean +/- standard deviation, in mEq/L.