Guidelines for sampling, measuring and reporting ionized magnesium in undiluted serum, plasma or blood : International Federation of Clinical Chemistry and Laboratory Medicine (IFCC)

• All analyzers with ion-selective electrodes for ionized magnesium (iMg) should yield comparable and unbiased results. The prerequisite to achieve this goal is to reach consensus on sampling, measurement and reporting. The recommended guidelines for sampling, measurement and reporting iMg in plasma ("plasma" refers to circulating plasma and the forms in which it is sampled: the plasma phase of anticoagulated whole blood, plasma separated from blood cells, or serum) or blood, referring to the substance concentration of iMg in the calibrants, will provide results for iMg that are approximately 3% greater than its true concentration, and 4% less than its true molality. Binding of magnesium to proteins and ligands in plasma and blood is pH-dependent. Therefore, pH should be simultaneously measured to allow adjustment of iMg concentration to pH 7.4. The substance concentration of iMg may be physiologically and consequently clinically more relevant than the substance concentration of total magnesium. © 2005 by Walter de Gruyter.

Nyckelord

Erythrocyte

Heparin

Influence factors

Interference

Ion-selective electrode

Ionized calcium

Ionized magnesium

Lipophilic anions

Liquid junction potential

pH

Protein

Sampling

Silicone

Sodium

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