Hypomagnesemia laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

The diagnosis can be made by finding a plasma magnesium concentration of less than 0.7mmol/l. Since most magnesium is intracellular, a body deficit can be present with a normal plasma concentration. In addition to hypomagnesemia, up to 40% cases will also have hypocalcemia while in up to 60% of cases, hypokalemia will also be present.

Serum magnesium level is usually normal for patients with hypomagnesemia since most of magnesium is intracellular. Some patients with hypomagnesemia may have the following laboratory findings:^[1]

• Serum magnesium level of less than 0.7 mmol/l.
• Hypocalcemia (40%)
• Hypokalemia (60%)