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Hypermagnesemia (High Level of Magnesium in the Blood)

by James L. Lewis, III, MD

In hypermagnesemia, the level of magnesium in blood is too high.

Bone contains most of the magnesium in the body. Very little circulates in the blood (see Overview of Magnesium). Hypermagnesemia is uncommon. It usually develops only when people with kidney failure are given magnesium salts or take drugs that contain magnesium (such as some antacids or laxatives).

Hypermagnesemia may cause weakness, low blood pressure, and impaired breathing. When hypermagnesemia is severe, the heart can stop beating.

The diagnosis is based on blood tests indicating that the magnesium level is high.

People with severe hypermagnesemia are given calcium gluconate intravenously. Diuretics (particularly if given intravenously) can increase the kidneys’ excretion of magnesium. However, if the kidneys are not functioning well or if hypermagnesemia is severe, dialysis is usually needed.