Hypomagnesemia

Low magnesium levels in the blood serum

Aetiology

• Alcohol

• Drugs - thiazide, PPIs

• GI illness with diarrhoea

• Pancreatitis

• Malabsorption

Clinical presentation

Symptoms

• Anorexia

• Nausea and vomiting

• Muscle weakness, lethargy

• Fits

Signs

• Cardiac arrhythmias

• Positive Chovestek sign and Trousseau sign indicate secondary hypocalcaemia

Investigations

• Serum magnesium low

• Measure other electrolytes, particularly K+ and Ca2+

Management

• Magnesium supplementation, calcium supplementation if needed

Complications

Secondary hypocalcaemia

• Calcium release from cells is dependent on magnesium

• In magnesium deficiency intracellular calcium is high

• PTH release inhibited

• Skeletal muscle receptors less sensitive to PTH