hypermagnesemia
The fastest way to identify magnesium deficiency or excess is using blood test on Mg determination. Routine serum magnesium test would significantly enhance the clinician's ability to identify disorders of magnesium metabolism. The resistance of potassium replenishing therapy can be avoided by identifying co-existing hypomagnesemia in hypokalemic patients thus repletion of Magnesium can be administer. While oral magnesium is the preferred route of repletion in critically ill patients, intravenous administration of magnesium is recommended.
In case of hypermagnesemia, refractory hypotension, mental obtundation, and respiratory arrest may occur. Hemodialysis is recommended for treatment of symptomatic hypermagnesemia.
Source: Compr Ther. 1997 Mar;23(3):168-73.