Serum Magnesium

Function

Magnesium is a vital intracellular cation involved in over 300 enzymatic reactions in the human body. It plays a critical role in energy production (ATP), DNA synthesis, muscle contraction, and maintaining a steady heart rhythm.

Why it is Ordered

Physicians order serum magnesium to investigate:

• Muscle weakness, tremors, or cramping.
• Cardiac arrhythmias (irregular heartbeats).
• Seizures or neurological irritability.
• Malabsorption issues or chronic alcoholism.
• Monitoring patients on certain medications like diuretics or proton pump inhibitors (PPIs).

Associated Conditions

• Hypomagnesemia (Low): Often linked to chronic diarrhea, Crohn's disease, alcoholism, or excessive use of diuretics.
• Hypermagnesemia (High): Primarily seen in advanced kidney failure or excessive intake of magnesium-containing antacids or laxatives.

Clinical Management

Magnesium balance is tightly regulated by the kidneys. Because only about 1% of the body's total magnesium is found in the blood (the rest is in bones and cells), a serum test may sometimes show 'normal' levels even if total body stores are depleted.