Hypermagnesemia is a serum magnesium concentration greater than 2.6 mg/dL.
Causes of hypermagnesemia include: renal failure, increased magnesium intake such as laxatives and antacids, treatment of eclampsia with intravenous MgSO4, and lithium-based psychotropic drugs which can reduce magnesium excretion.
Clinical presentations of hypermagnesemia include: lethargy, drowsiness, hypotension, nausea, vomiting, facial flushing, urinary retention, ileus, loss of DTRs, respiratory depression, respiratory arrest, oliguria, shortness of breath, and cardiac arrest (> 15 mg/dL).
At serum magnesium concentrations greater than 6 mg/dL, the ECG shows prolongation of the PR interval, widening of the QRS complex, increased T-wave amplitude, and irregular conduction.
The withdrawal of the magnesium infusion is usually sufficient to treat most cases of hypermagnesemia when the patient has normal renal function.
Hydration should be initiated with saline diuresis and furosemide.
Administration of intravenous furosemide can increase magnesium excretion when volume status and renal function are adequate.
In patients who have severe complications, calcium gluconate or calcium chloride can be used to treat hypermagnesemia.
These medications work by increasing the levels of calcium in the blood, which can help counteract the muscle and heart effects of excess magnesium.
Patients who have ARF or ESRD may require hemodialysis. Peritoneal dialysis can also be used to effectively remove magnesium in patients who cannot tolerate hemodialysis.
Take Home Message
In conclusion, hypermagnesemia is a serum magnesium > 2.6 mg/dL.
The major cause is renal failure.
Symptoms include hypotension, respiratory depression, and cardiac arrest.
Diagnosis is by measurement of serum magnesium concentration.
Treatment includes intravenous calcium gluconate and possibly furosemide.