hypomagnesemi

Hypomagnesemi, or hypomagnesemia, is a condition characterized by low levels of magnesium in the blood. Normal serum magnesium concentrations are about 1.7–2.2 mg/dL (0.70–1.10 mmol/L); hypomagnesemia is typically defined as levels below 1.7 mg/dL.

Causes of hypomagnesemi are diverse and include inadequate intake or absorption (malnutrition, alcoholism, gastrointestinal diseases such as Crohn’s disease or celiac disease), redistribution from the extracellular to intracellular space (acute pancreatitis, sepsis), and increased losses (diarrhea, vomiting, poorly controlled diabetes). Medications and medical therapies commonly contribute, including loop diuretics (furosemide), thiazide diuretics, proton pump inhibitors with long-term use, aminoglycoside antibiotics, amphotericin B, cisplatin, and certain immunosuppressants. Renal tubular disorders can also cause renal magnesium wasting. Chronic alcohol use, malnutrition, and advanced age are notable risk factors.

Symptoms range from asymptomatic to neuromuscular and cardiovascular manifestations. Mild cases may cause fatigue or irritability, while more significant deficiencies can produce muscle cramps, tremor, nystagmus, seizures, and signs of hypocalcemia or hypokalemia. Cardiac effects include QT prolongation and risk of torsades de pointes, particularly in the setting of other electrolyte abnormalities.

Diagnosis is based on serum magnesium measurement, with consideration of urine magnesium tests to distinguish renal from nonrenal losses. Evaluation often includes assessment of calcium, potassium, kidney function, and the patient’s medications and comorbidities.

Treatment depends on severity. Mild hypomagnesemi is usually corrected with oral magnesium supplements (for example, magnesium oxide or magnesium citrate). Moderate to severe or symptomatic cases require intravenous magnesium sulfate, commonly 1–2 g IV, followed by maintenance infusion or oral supplementation once stabilized. Correcting coexisting electrolyte disturbances and treating the underlying cause are essential. Most patients improve with appropriate therapy, though recurrent hypomagnesemi may require ongoing management.