Magnesium

Clinical Chemistry

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Description

Magnesium is a major intracellular ion and is a cofactor of many enzyme systems. Approximately 69% of magnesium ions are stored in bone, with less than 0.5% of total body magnesium being present in plasma. In plasma about 70% is present in the free form while the other 30% is complexed or bound to proteins (especially albumin). Plasma levels are therefore affected by plasma protein concentrations and pH. Significant depletion can cause hypokalaemia or hypocalcaemia. Regulation takes place mainly via the kidneys, especially via the ascending loop of Henle.

For guidance on the causes, investigation and management of hypomagnesaemia in adults in primary care see Clinical Chemistry guidelines available on CCG portal.

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Indications

Alcoholism, hypokalaemia, unexplained hypocalcaemia, prolonged diarrhoea, malnutrition or TPN, long-term PPI treatment, diuretics or nephrotoxic drugs and dysrhythmias.

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Sample Type

Serum, SST/Gel, minimum 2 mL (1 mL separated serum). 24 hour urine, no preservative

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Reference Range

Reference ranges are provided on the report. Alternatively, please contact the laboratory for current ranges.

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Turnaround Time

24 Hours

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Testing Frequency

As required

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External Notes

Magnesium is approximately 30 - 35% protein bound in plasma. Effective plasma levels are therefore affected by plasma protein concentrations. Signficant depletion usually causes hypokalaemia or hypocalcaemia.

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Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.