Magnesium deficiency in critically ill patients

Area of Science:

• Critical Care Medicine
• Clinical Biochemistry
• Nutritional Science

Background:

• Magnesium is essential for cellular function.
• Magnesium depletion is common in critically ill patients.
• Accurate assessment of magnesium status is crucial for patient management.

Purpose of the Study:

• To evaluate the utility of intracellular magnesium levels in peripheral blood cells as an indicator of tissue magnesium content.
• To determine if blood cell magnesium concentrations can reliably diagnose magnesium depletion in critically ill patients.

Main Methods:

• A magnesium loading test was employed to categorize 16 critically ill patients into magnesium-depleted and non-depleted groups.
• Plasma and intracellular magnesium concentrations (red blood cells and mononuclear blood cells) were measured pre-infusion.

Main Results:

• No significant differences in plasma, red blood cell, or mononuclear blood cell magnesium levels were observed between the depleted and non-depleted groups.
• Mean plasma magnesium: 0.81 vs. 0.90 mmol/L.
• Mean red blood cell magnesium: 2.34 vs. 2.18 mmol/L.
• Mean mononuclear blood cell magnesium: 25.16 vs. 18.1 mmol/kg dry weight.

Conclusions:

• Plasma and intracellular magnesium levels in peripheral blood cells are unreliable indicators of tissue magnesium status in critically ill patients.
• Magnesium depletion cannot be excluded even with normal blood cell magnesium concentrations.
• Further research is needed to identify reliable biomarkers for magnesium status in critical illness.