GUIDELINE FOR THE MANAGEMENT OF HYPOMAGNESAEMIA IN ADULTS

The reference magnesium range is 0.7 – 1.0 mmol/L

It is recommended that a diagnosis and correction of the primary cause of hypomagnesaemia is identified as oral magnesium (Mg) salts are not well absorbed by the gastrointestinal system and can cause diarrhoea. Possible causes include:

- Drugs

o Proton pump inhibitors

o Diuretics, especially loop and thiazide diuretics

o Aminoglycosides

o Ciclosporin

o Abusive use of laxatives

o Cancer chemotherapy in particular cisplatin

- Osmotic diuresis (diabetes)

- Inherited Disorders (this includes Gitelman’s syndrome)

- Lactation

- Reduced absorption (Coeliac Disease, chronic diarrhoea, short bowel syndrome, malnutrition)

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Mild hypomagnesaemia Moderate hypomagnesaemia 2+ Mg ≥ 0.5mmol/L Mg2+ < 0.5mmol/L

* Symptomatic – refer to secondary care Asymptomatic

Oral Supplementation IV Supplementation First Line: Magnesium aspartate dehydrate – Magnaspartate® 5g of magnesium sulphate (20mmol Mg) in 1 litre of 1-2 sachets daily = 10-20mmol Mg sodium chloride 0.9% or glucose 5% over 3 hours

Second Line: Magnesium glycerophosphate – YourMag® 2 x 4mmol tablet three times a day = 24mmol Mg Please note that YourMag is an unlicensed product and should only be used for patients that cannot use the sachets.

* Examples of symptoms include: abnormal eye movements, convulsions, fatigue, muscle spasms or cramps, muscle weakness, numbness.

ORAL MAGNESIUM REPLACEMENT

Oral magnesium should be considered first as if magnesium levels are increased too rapidly (e.g. by intravenous replacement), this will partially remove the stimulus for magnesium retention and up to 50% of the infused magnesium is excreted in the urine.

Oral magnesium salts commonly cause diarrhoea which may be minimised by administration with or after food.

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PARENTERAL MAGNESIUM REPLACEMENT

Use only if oral magnesium replacement is not appropriate. Parenteral magnesium should be avoided in patients with heart block or myocardial damage.

Document reference HypomagnesaemiaAdultsGUI201601v1.0final Author Erum Haq, Senior Pharmacist, Mid Essex CCG Consulted with n/a Approved by Mid-Essex Area Prescribing Committee Date approved January 2016 Next review date January 2018

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