What are the signs and symptoms of hypomagnesemia (low magnesium levels)?

Signs and Symptoms of Hypomagnesemia

Hypomagnesemia, defined as a serum magnesium concentration below 1.3 mEq/L, presents with a wide range of clinical manifestations that can significantly impact morbidity and mortality if not promptly recognized and treated. 1

Neurological Manifestations

• Neuromuscular hyperexcitability including tremor, myoclonic jerks, and convulsions 2
• Positive Chvostek sign and Trousseau sign (rarely) 2
• Ataxia and nystagmus 2
• Irritability and confusion 1
• Seizures, which can be a life-threatening complication 1
• Hallucinations in advanced cases 1

Cardiovascular Manifestations

• Polymorphic ventricular tachycardia, including torsades de pointes 1
• Cardiac arrhythmias that may lead to cardiorespiratory arrest if severe 1
• Increased sensitivity to digoxin toxicity 3
• Poor prognosis in cardiac arrest patients with low magnesium levels 1

Electrolyte Abnormalities

• Secondary hypokalemia that is resistant to potassium replacement alone 2, 3
• Secondary hypocalcemia that responds only to magnesium therapy 2, 3
• Both conditions can worsen the clinical presentation and complicate management 4

Musculoskeletal Manifestations

• Muscle weakness and cramps 2
• Contractures and severe pain 1
• Spontaneous carpopedal spasm (rarely) 2

Gastrointestinal Manifestations

• Abdominal cramps 1
• Dysphagia 2

Other Manifestations

• Fatigue and weakness 1
• Impaired wound healing 1
• Bone pain 1

Severity Correlation

• Most patients with mild hypomagnesemia (>1.2 mg/dL) are asymptomatic 5
• Symptoms typically appear when serum magnesium falls below 1.2 mg/dL 5
• Life-threatening manifestations (cardiac arrhythmias, seizures) occur with severe deficiency 1, 5

Common Causes

• Decreased absorption or increased loss from kidneys or intestines (diarrhea) 1
• Medication-induced: diuretics, certain chemotherapy drugs (cisplatin, cetuximab), pentamidine, and alcohol 1
• Alterations in thyroid hormone function 1
• Malnourishment 1
• Gastrointestinal disorders causing malabsorption 3

Clinical Pitfalls and Caveats

• Serum magnesium levels may not accurately reflect total body magnesium status as less than 1% of magnesium stores are in the blood 1
• Hypomagnesemia should be suspected in patients with refractory hypokalemia or hypocalcemia 2, 3
• Magnesium deficiency can be present despite normal serum levels, particularly in critically ill patients 4
• Patients at risk should be considered for treatment even with serum magnesium within the normal range if clinical symptoms suggest deficiency 4
• Magnesium replacement is essential for treating associated electrolyte abnormalities 2, 3