Overview
Hypomagnesaemia describes a low serum magnesium ion concentration. Magnesium is important in all enzyme processes, DNA, RNA, and protein synthesis, calcium and potassium ion channel regulation, muscle contraction, and many other physiological functions.
Causes
- Dietary deficiency – the most common cause
- Diuretic use
- Proton pump inhibitors
- Chronic alcohol abuse
- Laxative abuse
- Malabsorption syndromes (e.g. coeliac disease)
- Pancreatitis
- Cirrhosis
- Diarrhoea
Presentation
Most cases are asymptomatic until magnesium levels are below 0.5 mmol/L. Features may be:
- Weakness
- Tremor
- Seizures
- Confusion
- Altered levels of consciousness (e.g. drowsiness, coma)
- Arrhythmia
- ECG features similar to hypokalaemia
Management
- If magnesium <0.4 mmol/L, tetany, arrhythmia, or seizures are present: IV magnesium replacement
- If magnesium >0.4 mmol/L and no other features: oral magnesium salts
- A common side effect of magnesium salts is diarrhoea
Complications
- Tetany
- Seizures
- Arrhythmia
