An intravenous magnesium infusion may be used to treat a low serum magnesium level. Normal serum magnesium is 1.5 to 2.5 mEq/L. Clinical manifestations of hypermagnesemia are the result of depressed neuromuscular transmission. Absent reflexes indicate a magnesium level around 7 mEq/L. Diarrhea and PVCs are not clinical manifestations of high magnesium levels. Hypermagnesemia causes hypotension.