Renal System >
Hypomagnesaemia

Electrolyte disturbance caused by serum magnesium levels less than 0.7mmol/L

Risk Factors
  • Alcoholism
  • Congestive heart failure
  • Diabetes
  • Chronic diarrhoea
  • Hypokalaemia
  • Hypocalcaemia
  • Malnutrition
Aetiology
  • Decreased GI absorption:
    • Diarrhoea
    • Malabsorption
    • Inadequate dietary intake
  • Increased renal loss
    • Diuresis secondary to alcohol
    • Glycosuria
    • Loop diuretic
Pathophysiology
  • Decreased gastrointestinal absorption, increased renal loss of magnesium
Clinical Presentation
  • Anorexia
  • Nausea & vomiting
  • Lethargy
  • Weakness
  • Personality change
  • Tetany (positive Trousseau sign or Chvostek sign)
  • Tremor and muscle fasciculations
Investigations
  • Measurement of serum magnesium concentration in patients with risk factors and unexplained hypocalcaemia or hypokalaemia
  • ECG
Management
  • Oral magnesium salts such as magnesium gluconate
  • IV or IM magnesium sulfate if severe (<0.5mmol/L) or cannot tolerate oral treatment
Complications
  • Cardiac arrhythmia
  • Seizures
  • Coronary artery vasospasm

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