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Kidney Week

Abstract: SA-PO706

A Mystery Solved: Getting a "Grip" on Unexplained Hypermagnesemia in a Patient on Continuous Cyclic Peritoneal Dialysis (CCPD)

Session Information

Category: Fluid, Electrolytes, and Acid-Base Disorders

  • 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Authors

  • Munir, Saba, Rush University Medical Center, Chicago, Illinois, United States
  • Korbet, Stephen M., Rush University Medical Center, Chicago, Illinois, United States
  • Rodby, Roger A., Rush University Medical Center, Chicago, Illinois, United States
Introduction

Hypermagnesemia should not occur in a patient on RRT without an exogenous source. We present a pt in whom a [Mg] level of 6.0 mg/dL was found in which there was no history of intake of any Mg containing mediations or supplements despite multiple inquiries.

Case Description

A 27 year old black woman with anuric ESKD secondary to Alport's disease on CCPD presented with a 1-wk history of weakness and syncopal episodes. She reported “blackout” and “spacing out" spells, each lasting a few seconds. She also noted new upper extremity weakness, spontaneously dropping items from her hands. She reported compliance with home PD (1.5 mEq/L [Mg] dialysate). She denied use of laxatives or supplements. She works as a chef and denied any recent increase in Mg containing foods.

In the ED her VS were unremarkable except for a BP of 170/90. Her laboratory values were typical for ESKD except for a serum [Mg] of 6.0 mg/dL (nl 1.7-2.7). Her EKG demonstrated a prolonged QTc. She received IV calcium, and her QTc normalized. She was admitted to the hospital and started on rapid exchange PD with a dialysate [Mg] of 0.5 mEq/L. Her neurologic episodes and muscular weakness resolved. Upon further investigation (by the dietician), the patient noted that she recently started rock climbing 4 times per week using climber’s chalk to improve her grip (the chalk helps keep hands dry to provide a stronger grip) which upon research was found to be made of magnesium carbonate (Figure 1). Her [Mg] improved in the hospital and decreased further at home with change to a lower [Mg] dialysate and stopping her rock climbing (Fig. 1).

Discussion

Magnesium is easily excreted by the kidneys when renal function is normal, so hypermagnesemia requires a large exogenous source in the setting of renal insufficiency. The exact mechanism by which she absorbed Mg from the climbing chalk remains uknown. Although a dialysate [Mg] of 1.5 mEq/L (0.75 mmol/L) is slightly high relative to a normal serum [Mg], her markedly elevated [Mg] of 6.0 mg/dL (2.5 mmol/L) had to be from an exogenous source that required “Dr. House” like investigation to solve.

Figure 1. Clinical course of magnesium