Magnesium Levels in Critically Ill Patients

Abstract

We studied the relation between ionized magnesium, total magnesium, and albumin levels in serum of 115 critically ill patients and the role of extracellular and intracellular magnesium in outcome prediction. Levels of serum total and ionized magnesium, serum albumin, and magnesium in mononuclear blood cells and erythrocytes were measured and the APACHE II score and 1-month mortality recorded. Of all patients, 51.3% had a serum total magnesium concentration below the reference range. In 71% of these hypomagnesemic patients, a normal serum ionized magnesium concentration was measured. None of the patients had an intracellular magnesium concentration below the reference limit. Except for serum total and ionized magnesium, none of the magnesium parameters correlated significantly with each other. A significantly negative correlation was found between serum albumin and the fraction ionized magnesium. There was no association between low extracellular or intracellular magnesium and clinical outcome. The observation of hypomagnesemia in critically ill patients depends on which magnesium fraction is measured. The lack of correlation with clinical outcome suggests hypomagnesemia to be merely an epiphenomenon. Reliable concentrations of serum ionized magnesium can be obtained only by direct measurement and not by calculation from serum total magnesium and albumin.

Renal Control of Calcium, Phosphate, and Magnesium Homeostasis

“…Hypomagnesemia is usually defined as serum magnesium,0.7 mmol/L, 1.4 mEq/L, or 1.7 mg/dl. Biochemical hypomagnesemia is common, with a prevalence of up to 15% in the general population and up to 65% in patients in the intensive care units (60)(61)(62)(63)(64)(102)(103)(104)(105)(106)(107)(108)(109). The causes of hypomagnesemia are listed in Table 3.…”

Prevalence of Hypomagnesemia and Its Predictive Prognostic Value in Critically Ill Medical Patients

“…Various studies evaluated hypomagnesemia in critically ill patients previously ranging from 14% -70%. [12][13][14][15][16][17][18] In our study a relatively higher mortality was observed among patients with hypomagnesemia compared to normomagnesemic patients. The relation between hypomagnesemia and mortality varies from study to study.…”

Dysmagnesaemia and outcome in a trauma ICU

“…Some have gone so far as to dismiss this correlation as an 'epiphenomenon' . [16] However, since the physiology underlying Mg regulation is not entirely understood, nor the pathophysiological factors that affect Mg homeostasis, not finding a correlation could simply mean that confounding factors have not been controlled appropriately, which is probable in a retrospective study of this nature, despite using an electronic patient record system.…”

“…[2,8] Its correlation with outcome among critically ill patients has been studied and varies greatly (Table 1). [9][10][11][12][13][14][15][16][17][18][19] Some studies have found an increased mortality associated with admission hypomagnesaemia, [11,12,17] ad mission hypermagnesaemia, [11,13,17] the development of hypo magnesmia, [18] and the development of hypermagnesaemia; [6] while others have found no correlation at all. [16,19] Similarly, the prevalence of admission hypomagnesaemia varies greatly among studies and, according to one report, is more common among trauma patients.…”