What are the symptoms of hypomagnesia?

Symptoms of Hypomagnesemia

Hypomagnesemia can present with a wide range of neurological, cardiovascular, and muscular symptoms, with the most serious manifestations including cardiac arrhythmias, seizures, and tetany when serum magnesium falls below 1.2 mg/dL. 1

Clinical Manifestations by Severity

Neuromuscular Symptoms

• Muscle irritability and hyperexcitability
• Tremors and clonic twitching 2
• Tetany
• Seizures (particularly when associated with hypocalcemia) 3
• Abnormal involuntary movements 3
• Decreased or absent deep tendon reflexes (in severe cases)
• Muscle weakness 4
• Ataxia

Cardiovascular Manifestations

• Cardiac arrhythmias, particularly:
  • Polymorphic ventricular tachycardia (torsades de pointes) 3
  • Prolonged QT interval
  • Increased sensitivity to digoxin 4
• Hypertension
• Vasospasm

Other Clinical Manifestations

• Fatigue and weakness 3
• Emotional irritability 3
• Confusion or altered mental status
• Nausea and vomiting
• Anorexia
• Paresthesias

Associated Electrolyte Abnormalities

Hypomagnesemia frequently occurs with other electrolyte disturbances that may contribute to the clinical presentation:

• Hypocalcemia (refractory to treatment until magnesium is repleted) 4
• Hypokalemia (resistant to correction without addressing magnesium deficiency) 4
• Metabolic alkalosis

Severity Correlation with Serum Levels

The severity of symptoms generally correlates with the degree of magnesium deficiency:

• Mild symptoms: Serum Mg 1.3-1.8 mg/dL
• Moderate symptoms: Serum Mg 1.0-1.2 mg/dL
• Severe symptoms: Serum Mg <1.0 mg/dL 1

High-Risk Populations

Hypomagnesemia is particularly common in:

• Critically ill patients 5
• Patients with alcoholism 4
• Diabetic patients 4
• Patients receiving certain medications:
  • Loop and thiazide diuretics
  • Aminoglycosides
  • Cisplatin
  • Pentamidine
  • Foscarnet 4
• Patients with gastrointestinal disorders causing malabsorption or increased losses
• Patients with renal disorders causing increased magnesium wasting

Clinical Pearls and Pitfalls

1. Serum magnesium levels may be normal despite significant intracellular magnesium depletion 4

2. Hypomagnesemia should be suspected in patients with refractory hypokalemia or hypocalcemia 4

3. Patients with 22q11.2 deletion syndrome are particularly susceptible to hypomagnesemia, which may worsen their hypocalcemia 3

4. For cardiotoxicity and cardiac arrest associated with hypomagnesemia, IV magnesium 1-2 g of MgSO4 bolus is recommended (Class I, LOE C) 3

5. Asymptomatic patients can be treated with oral magnesium supplements, while symptomatic patients with severe deficiency (<1.2 mg/dL) require parenteral magnesium 1

6. Always assess renal function before administering magnesium supplementation, as impaired renal function can lead to hypermagnesemia 1

Recognizing the symptoms of hypomagnesemia is crucial for timely diagnosis and treatment, particularly in high-risk populations, as untreated severe hypomagnesemia can lead to life-threatening complications.