Ionized, not Total Magnesium is a Better Biomarker for Hypomagnesemia in Renal Replacement Therapy

Hypomagnesemia is common in critically ill patients undergoing renal replacement therapy (RRT) and is associated with increased risk of mortality. Measurement of total plasma magnesium (tMg) is the current clinical practice to assess hypomagnesemia in these patients. However, tMg does not accurately represent the level of ionized magnesium (iMg), the physiologically active fraction of magnesium in blood. Multiple reasons that favor iMg and not tMg in assessing RRT-related hypomagnesemia will be discussed.

This webinar will describe an RRT patient population with consistently normal tMg but low iMg. These patients were undergoing continuous venovenous hemofiltration (CVVH) using citrate anticoagulation. In this population, iMg and not tMg was a better discriminating marker for hypomagnesemia and the requirement for magnesium supplementation. The superior detection of hypomagnesemia through iMg testing has particular application to COVID-19 patients since this group often requires a higher citrate concentration during CVVH.

Learning Objectives

• Identify the physiologically active fraction of magnesium in blood
• Review reports of RRT patients with low ionized magnesium but normal total magnesium
• Identify factors that make ionized magnesium a better indicator of hypomagnesemia than total magneisum in RRT

Educational Credits

This program offers 1 hour of P.A.C.E. continuing education credits.

This program has been approved by the American Association of Critical Care Nurses (AACN), for 1.00 CERPs, Synergy CERP Category A, File Number 23499. Approval refers to recognition of continuing education only and does not imply AACN approval or endorsement of the content of this educational activity, or the products mentioned.

Registration Available Online here