magnesium
Hypomagnesemia
Definition
Magnesium ‹0.7mmol/LCause
- Medications: eg: digoxin, diuretics, aminoglycosides, theophylline, PPI's
- reduced intake or malabsorption such as in Coeliac, Crohns
- excessive losses: diarrhoea, fistulae, renal losses
- alcoholism, uncontrolled diabetes, genetic causes, other
Clinical
especially if ‹0.5mmol/L- Anorexia, nausea
- confusion, weakness, ataxia, paraesthesia
- tetany, tremor, muscle fasciculations.
- Arrhythmias: AF, extra systoles, myocardial ischaemia
- Seizures, drowsiness and coma with very low levels
Diagnostics
- U&E, Mg, Calcium, Phosphate, Glucose
- ECG examining for arrhythmias
Management
- treat underlying cause (check Glu and correct)
- review and stop offending medications
- if symptomatic - will need hospitalisation and IV administration
- asymptomatic - oral replacement - beware those with reduced renal function eGFR≤30
- oral replacement may cause diarrhoea
- replacement of K+ may also be warranted
| se Mg(mmol/L) | Options |
|---|---|
| 0.5 - 0.7 with symptoms or 0.4 - 0.5 without symptoms | Mg aspartate 1 sachet (10mmol) bd or Mg glycerophosphate 2-4mmol chewable tablets tds |
| 0.4 - 0.5 with symptoms or ‹0.4 with/without symptoms | Probably requires Hospital admission for IV MgSO4 |
Author: Dr Dylan Jenkins, Dec 2023 refs