Magnesium
- Roles of Magnesium
- Coenzyme in metabolism of carbohydrates
- Required for DNA and protein synthesis
- Blood glucose control
- BP regulation
- Necessary for ATP production
- Acts directly on myoneural junction
- Important for normal cardiac function
- 50% to 60% contained in bone
- Absorbed in GI tract
- Excreted by kidneys
- Hypermagnesemia
- High serum Mg caused by
- Increased intake or ingestion of products containing magnesium when renal insufficiency or failure is present
- Excess IV magnesium administration
- Manifestations
- Lethargy
- Nausea and vomiting
- Impaired reflexes
- Muscle paralysis
- Respiratory and cardiac arrest
- Urinary retention
- Flushed, warm skin, especially facial
- Decreased Pulse, Decreased BP
- Management
- Prevention first—restrict magnesium intake in high-risk patients
- IV CaCl or calcium gluconate if symptomatic
- Fluids and IV furosemide to promote urinary excretion
- Dialysis
- High serum Mg caused by
- Hypomagnesemia
- Low serum Mg caused by
- Prolonged fasting or starvation
- Chronic alcoholism
- Fluid loss from gastrointestinal tract
- Prolonged parenteral nutrition without supplementation
- Diuretics
- Hyperglycemic osmotic diuresis
- Manifestations
- Hyperactive deep tendon reflexes
- Muscle cramps
- Tremors
- Seizures and confusion
- Cardiac dysrhythmias
- Corresponding hypocalcemia and hypokalemia
- Chvostek’s and Trousseau’s signs
- Increased Pulse, Increased BP, dysrhythmias
- Management
- Treat underlying cause
- Oral supplements
- Increase dietary intake
- Parenteral IV or IM magnesium when severe
- Low serum Mg caused by
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Magnesium Imbalances: Causes and Manifestations |
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Hypermagnesemia (Mg+ >2.5 mEq/L [1.25 mmol/L]) |
Hypomagnesemia (Mg+ <1.5 mEq/L [0.75 mmol/L]) |
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