Symptoms of Hypomagnesemia
Hypomagnesemia, defined as a serum magnesium concentration below 1.3 mEq/L, can cause severe and potentially fatal complications if not timely diagnosed and properly treated, with symptoms typically appearing when levels fall below 1.2 mg/dL. 1, 2
Neurological and Neuromuscular Symptoms
- Neuromuscular hyperactivity including tremor, myoclonic jerks, and convulsions 3
- Positive Chvostek sign (facial muscle twitching when the facial nerve is tapped) and Trousseau sign (carpal spasm induced by inflation of a blood pressure cuff) 3, 4
- Paresthesias (abnormal sensations like tingling or numbness) 4
- Ataxia (lack of muscle coordination) and nystagmus (involuntary eye movement) 3
- Seizures, which can be a life-threatening manifestation 1
- Abnormal involuntary movements of various types 1
Cardiovascular Manifestations
- Cardiac arrhythmias, particularly polymorphic ventricular tachycardia and torsades de pointes 1, 3
- Increased sensitivity to digoxin toxicity 5
- Prolongation of the QT interval on electrocardiogram 1
- Ventricular fibrillation and risk of sudden death in severe cases 3
Metabolic and Electrolyte Disturbances
- Secondary hypokalemia that is resistant to potassium supplementation alone 5
- Secondary hypocalcemia that responds only to magnesium therapy 3
- Metabolic alkalosis, particularly in cases associated with renal magnesium wasting 2
Psychiatric and Cognitive Symptoms
- Psychiatric disturbances ranging from apathy to delirium 3
- Confusion and altered mental status 3
- Drowsiness that can progress to coma in severe cases 1
Other Clinical Manifestations
- Fatigue and general weakness 1
- Emotional irritability 1
- Dysphagia (difficulty swallowing) 3
- Increased risk of osteopenia and osteoporosis with chronic deficiency 1
High-Risk Situations
- Symptoms may worsen during biological stress (surgery, childbirth, infection) 1
- Alcohol consumption or carbonated beverages (especially colas) can worsen hypomagnesemia 1
- Certain medications (pentamidine, diuretics, alcohol) can induce or worsen hypomagnesemia 1, 5
Diagnostic Considerations
- Many patients with hypomagnesemia are asymptomatic, especially with mild deficiency 2
- Symptoms typically don't appear until serum magnesium falls below 1.2 mg/dL 2
- Serum magnesium can be normal despite intracellular magnesium depletion 5
- Fractional excretion of magnesium below 2% suggests non-renal causes of hypomagnesemia 2
It's important to note that hypomagnesemia is common in hospitalized patients (11% of general hospital population and up to 65% of critically ill patients) and requires prompt recognition and treatment to prevent serious complications 6.