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Serum magnesium concentrations after repetitive magnesium cathartic administration
J A Woodard1, M Shannon, P G Lacouture
1Massachusetts Poison Control System, Harvard Medical School, Boston 02115.
The American Journal of Emergency Medicine
|July 1, 1990
Summary
Repetitive use of magnesium citrate for toxic ingestions causes serum magnesium levels to rise modestly. Close monitoring allows safe administration, preventing severe hypermagnesemia.
Area of Science:
- Toxicology
- Clinical Chemistry
Background:
- Multiple doses of magnesium-containing cathartics can lead to severe hypermagnesemia in toxic ingestion cases.
- The frequency and magnitude of serum magnesium elevations require further investigation.
Purpose of the Study:
- To prospectively evaluate serum magnesium levels after repetitive magnesium citrate administration in overdose patients.
- To determine the correlation between magnesium citrate dosage and serum magnesium increase.
Main Methods:
- 102 patients receiving multiple doses of magnesium citrate for overdose were studied.
- Serial measurements of electrolytes, BUN, creatinine, calcium, and magnesium were performed.
- Commonly ingested substances included tricyclic antidepressants, aspirin, and phenytoin.
Main Results:
- Mean serum magnesium increased from 1.8 to 2.5 mEq/L after a mean of 960 mL magnesium citrate.
- 47% of patients had elevated serum magnesium (>2.4 mEq/L), with 12% exceeding 3.0 mEq/L.
- No correlation was found between the total magnesium citrate quantity and the serum magnesium increment.
Conclusions:
- Repetitive magnesium citrate use consistently elevates serum magnesium concentrations.
- The observed rise in serum magnesium is generally modest and manageable.
- With careful monitoring, magnesium citrate can be safely used without causing severe hypermagnesemia.