Hypomagnesemia

Definition:

Hypomagnesemia means low levels of magnesium in the blood.

Alternative Names:

Low blood magnesium; Magnesium - low

Causes, incidence, and risk factors:

Several conditions can cause hypomagnesemia, including:

Alcoholism
Chronic diarrhea
High blood calcium levels (hypercalcemia)
Hyperaldosteronism
Malabsorption syndromes, such as celiac disease and inflammatory bowel disease
Malnutrition
Medications including amphotericin, cisplatin, cyclosporine, diuretics, and aminoglycoside antibiotics
Excessive urination (polyuria), such as in uncontrolled diabetes and during recovery from acute kidney failure
Sweating

Symptoms:

Common symptoms include:

Abnormal eye movements (nystagmus)
Convulsions
Fatigue
Muscle spasms or cramps
Muscle weakness
Numbness

Signs and tests:

Your health care provider will do a complete physical examination to help determine the cause of your symptoms.

Signs include:

Electrocardiogram (ECG) changes
Low blood calcium level (hypocalcemia)
Low blood potassium level (hypokalemia)

Blood and urine tests will be done. Other tests that can confirm hypomagnesemia include:

Comprehensive metabolic panel
Magnesium blood test
Urine magnesium test

Treatment:

The cause of hypomagnesemia must be diagnosed and treated. Treatment depends on the type of hypomagnesemia, but may include:

Fluids given through a vein (IV)
Magnesium by mouth or through a vein
Medication to relieve symptoms

Expectations (prognosis):

The outcome depends on the condition that is causing the problem.

Complications:

Cardiac arrest
Death
Respiratory arrest

Calling your health care provider:

Hypomagnesemia can be a life-threatening emergency. Call your health care provider if you have symptoms of this condition.

Prevention:

Treating the condition that is causing hypomagnesemia can help. If you play any demanding sports, drink fluids that contain electrolytes (sports drinks). Drinking only water while you take part in high-energy athletic events can lead to acute hypomagnesemia.

References:

Pollak MR, Yu ASL, Taylor EN. Disorders of calcium, magnesium, and phosphorous balance. In: Brenner BM, ed. Brenner and Rector's The Kidney. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 16.

Yu ASL. Disorders of magnesium and phosphorous. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 120.