What are the signs and symptoms of magnesium deficiency?

Signs and Symptoms of Magnesium Deficiency

Magnesium deficiency presents with a wide spectrum of clinical manifestations including neuromuscular hyperexcitability, cardiac arrhythmias, and biochemical abnormalities such as hypokalemia and hypocalcemia that may significantly impact morbidity and mortality. 1

Definition and Prevalence

• Magnesium deficiency is common, with approximately 10% of hospitalized patients being hypomagnesemic 1
• Serum magnesium levels <1.3 mEq/L are undisputedly low, though normal values may vary between laboratories 2
• Importantly, intracellular magnesium depletion may be present despite normal serum magnesium levels 1, 3

Neuromuscular Manifestations

• Neuromuscular hyperexcitability is a hallmark sign of magnesium deficiency 4, 1
• Specific manifestations include:
  • Tremor and myoclonic jerks 4
  • Convulsions 4
  • Positive Chvostek sign and occasionally Trousseau sign 4
  • Spontaneous carpopedal spasm (rare) 4
  • Ataxia and nystagmus 4
  • Dysphagia 4
  • Muscle weakness and cramps 5

Cardiovascular Manifestations

• Various cardiac arrhythmias may occur, including:
  • Ventricular arrhythmias (PVCs, VT, torsades de pointes) 2
  • Increased risk of ventricular fibrillation 4
  • Increased sensitivity to digitalis toxicity 3
  • Hypertension 5

Electrocardiographic Changes

• ECG abnormalities may be present, particularly with more severe deficiency 2
• Prolonged PR, QRS, and QT intervals may be observed 2

Electrolyte Abnormalities

• Refractory hypokalemia - not easily corrected without magnesium replacement 4, 3
• Hypocalcemia that responds only to magnesium therapy 4, 3

Gastrointestinal Manifestations

• Abdominal cramps 2
• In inflammatory bowel disease patients, magnesium deficiency occurs in 13-88% of cases 2

Other Clinical Manifestations

• Fatigue 2
• Bone pain 2
• Impaired wound healing 2
• Psychiatric disturbances ranging from apathy to delirium 4
• Increased susceptibility to infections 5

Populations at High Risk

• Patients with heart failure on diuretics 2
• Alcoholics 3
• Diabetic patients 3
• Patients with gastrointestinal disorders:
  • Malabsorption syndromes 3
  • Chronic diarrhea 3
  • Short bowel syndrome 3
  • Inflammatory bowel disease 2
• Patients on certain medications:
  • Loop and thiazide diuretics 3
  • Aminoglycosides 3
  • Proton pump inhibitors 2
  • Cisplatin and other chemotherapeutic agents 3

Diagnostic Challenges

• Serum magnesium is not an accurate measurement of total body magnesium status since less than 1% of magnesium stores are in the blood 2
• The remainder of magnesium is stored in bone, soft tissue, and muscle 2
• Parenteral magnesium load test may be more accurate for detecting deficiency 3

Clinical Pitfalls

• Normal serum magnesium levels do not exclude significant intracellular magnesium depletion 1, 3
• Magnesium deficiency may be overlooked as a cause of refractory hypokalemia and hypocalcemia 4, 3
• Symptoms may begin insidiously or with dramatic suddenness, or there may be no overt symptoms initially 4
• Magnesium deficiency can worsen the cardiotoxic effects of digitalis 3
• In critically ill patients, the prevalence of hypomagnesemia can be as high as 60-65%, significantly affecting outcomes 2

Recognizing these signs and symptoms is crucial for early detection and treatment of magnesium deficiency to prevent potentially serious complications including cardiac arrhythmias and sudden death.