Hypermagnesemia is an uncommon problem in the absence of magnesium administration or renal failure. (See "Causes and treatment of hypermagnesemia".)
When it occurs, the elevation in the plasma magnesium concentration is usually mild (<3 meq/L, 3.6 mg/dL, or 1.5 mmol/L) and the patient is asymptomatic. However, clinical symptoms may be seen when the plasma magnesium concentration exceeds 4 meq/L (4.8 mg/dL or 2 mmol/L).
The clinical manifestations of hypermagnesemia are discussed in this topic. The regulation of magnesium balance and the causes and treatment of hypermagnesemia are presented elsewhere. (See "Regulation of magnesium balance" and "Causes and treatment of hypermagnesemia".)
OVERVIEW OF SYMPTOMS
The approximate relation between clinical manifestations and the degree of hypermagnesemia can be summarized as follows:
●Plasma magnesium concentration 4 to 6 meq/L (4.8 to 7.2 mg/dL or 2 to 3 mmol/L) – nausea, flushing, headache, lethargy, drowsiness, and diminished deep tendon reflexes.