Abstract: FR-PO571
Ionized Magnesium Correlates With Total Magnesium in High-Risk Kidney Cohorts
Session Information
- Fluid, Electrolyte, and Acid-Base Disorders: Clinical
November 04, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
Abstract Time: 10:00 AM - 12:00 PM
Category: Fluid‚ Electrolyte‚ and Acid-Base Disorders
- 1002 Fluid‚ Electrolyte‚ and Acid-Base Disorders: Clinical
Authors
- Hasson, Denise Claire, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
- Rose, James, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
- Merrill, Kyle, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
- Varnell, Charles D., Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
- Goldstein, Stuart, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
- Benoit, Stefanie W., Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
Background
Serum magnesium (Mg) abnormalities are common in critically ill children and kidney transplant (KTx) recipients; abnormal values are associated with poor outcomes including mortality. Mg homeostasis is affected by kidney function, acid-base status, calcium-vitamin D alterations, and medications (eg, immunosuppressants, citrate). The active form, ionized Mg (iMg), is not measured, and studies conflict regarding total (tMg) and iMg correlation. We hypothesized iMg and tMg concentrations will be categorized differently (i.e., low, normal, high) in patients (pts) after KTx and on continuous kidney replacement therapy (CKRT) with citrate, but ionized calcium (iCa) will correlate with iMg.
Methods
We collected whole blood from pts in a single center for iMg and iCa measurement. Each CKRT pt could contribute multiple samples as our timepoints would reset with each circuit change. Total Mg and Ca were collected as standard of care. Demographic, lab, and outcome data were recorded from the medical record. iMg and iCal were categorized using normal ranges of 0.44-0.65 mmol/L and 1.0-1.3 mmol/L, respectively, based on prior studies and clinical significance. Fisher’s Exact test and Pearson correlation studies were used for statistical analysis.
Results
In 9 KTx pts (n= 28 samples), iMg and tMg had similar categorization (p<0.001) and correlated well (R=0.811, p<0.001, Table 1A, Figure 1A), but iCa did not differentiate normal from abnormal iMg concentrations (p=0.118). In 11 CKRT pts (n=70 samples), more time on CKRT resulted in more ionized hypomagnesemia despite 65/70 samples having normal tMgs: 17/30 (57%) of pre-CRRT, 15/19 (79%) of 1-2 hour, and 15/16 (94%) of 18-28 hour iMgs were low. On CKRT, there was category agreement (p=0.028) and moderate correlation between iMg and tMg (R=0.54, p<0.0001), but poor category agreement (p=0.50) and correlation between iMg and iCa (R=0.178, p=0.138).
Conclusion
iMg and tMg correlate in both groups, with greater category agreement in the KTx cohort, thus tMg likely represents active Mg in these pts. CKRT patients exposed to citrate had progressive ionized hypomagnesemia despite normal tMg and may benefit from supplementation. iCa should not be used as a surrogate for iMg concentrations.
Funding
- Commercial Support –