Hypomagnesemia Clinical Presentation

Updated: Jul 19, 2022
  • Author: Tibor Fulop, MD, PhD, FACP, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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At least 10 inherited disorders of magnesium handling cause hypomagnesemia. [117] Consequently, a careful family history is important, particularly when acquired causes of hypomagnesemia have been excluded.

Magnesium is critically important in maintaining normal cell function, and symptomatic magnesium depletion is often associated with multiple biochemical abnormalities, including hypokalemia, hypocalcemia, and metabolic acidosis. As a result, hypomagnesemia is sometimes difficult to attribute solely to specific clinical manifestations.

The organ systems commonly affected by magnesium deficiency are the cardiovascular system and the central and peripheral nervous systems. The skeletal, hematologic, gastrointestinal, and genitourinary systems are affected less often.

Neuromuscular manifestations of hypomagnesemia may include the following [5] :

  • Muscular weakness
  • Tremors
  • Seizure
  • Paresthesias
  • Tetany
  • Positive Chvostek sign and Trousseau sign
  • Vertical and horizontal nystagmus

Cardiovascular manifestations may include the following electrocardiographic abnormalities and arrhythmias:

  • Nonspecific T-wave changes - U waves
  • Prolonged QT and QU interval
  • Repolarization alternans
  • Premature ventricular contractions - Monomorphic ventricular tachycardia
  • Torsade de pointes
  • Ventricular fibrillation
  • Enhanced digitalis toxicity

Metabolic manifestations may include the following:

  • Hypokalemia
  • Hypocalcemia

Physical Examination

At serum magnesium levels less than 1 mEq/L, patients develop the following signs:

  • Tremor
  • Hyperactive deep-tendon reflexes
  • Hyperreactivity to sensory stimuli
  • Muscular fibrillations
  • Positive Chvostek and Trousseau signs
  • Carpopedal spasms progressing to tetany
  • Vertical nystagmus

Mental status changes may become evident and may include irritability, disorientation, depression, and psychosis. Cardiac arrhythmias and reversible respiratory muscle failure can also occur in severe hypomagnesemia.

In a fashion analogous to hypermagnesemia, the rate of development of hypomagnesemia may be more important than the absolute value in terms of symptom development.