Red blood cell magnesium concentrations: analytical problems and significance

Area of Science:

• Biochemistry
• Analytical Chemistry
• Cell Biology

Background:

• Magnesium is crucial for cellular function.
• Accurate measurement of magnesium in human red blood cells (erythrocytes) is essential for clinical assessment.
• Existing methods for measuring total and ionized magnesium have limitations.

Purpose of the Study:

• To evaluate methods for assessing total magnesium concentrations in human red blood cells (ErMg).
• To determine normal values for ErMg.
• To discuss the challenges and significance of measuring ionized magnesium in erythrocytes.

Main Methods:

• Atomic Absorption Spectrometry (AAS) for total ErMg.
• Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Particle Induced X-ray Emission (PIXE) for multielemental analysis.
• Microelectrodes, NMR (31P NMR method), and zero point titration for ionized magnesium (Mg2+).

Main Results:

• Normal ErMg values are 2.3 +/- 0.24 mmol/litre of packed cells using a direct AAS method.
• Ionized magnesium concentrations vary significantly depending on the method: 0.20 +/- 0.02 mmol/litre cell water (NMR) and 0.55 +/- 0.12 (zero point titration).
• Free magnesium is a small fraction of total magnesium and its in vivo oscillations complicate accurate measurement.

Conclusions:

• AAS is a reliable method for total ErMg assessment.
• Measuring ionized magnesium in erythrocytes is complex due to technical limitations and dynamic in vivo changes.
• Further research is needed to understand the clinical significance of magnesium variations in red blood cells.