Hypomagnesemia

Causes

Mg plasma concentration < 0.7 mmol/L. It is usually latent but is associated with increased morbidity and mortality in intensive care. Severe hypoMg is often accompanied by calcium resistant hypocalcemia. It could be due to the inhibition of secretion of parathyroid hormone and peripheral resistance to its action.

Clinical signs of hypomagnesemia.
Neuromuscular manifestations	Hyperexcitability Twitching, myoclonus, tetany Paralysis (deep hypomagnesemia) Behavioral disorders (irritability, anxiety, delirium)
Cardiovascular events	Arrhythmia (torsades de pointe, ventricular tachycardia) Changes of ECG (prolonged PR interval, modification of the T wave) Coronary spasm High blood pressure
Metabolic disorders	Hypokalemia Hypocalcemia

Causes of the hypomagnesemias.
Inadequate intake	Malnutrition Inadequate parenteral nutrition
Digestive problems (faulty absorption or increased losses)	Vomiting or prolonged gastric suction Acute or chronic diarrhea Biliary or intestinal fistula Intestinal malabsorption Acute pancreatitis Alcoholic cirrhosis
Renal losses	Congenital anomalies of the renal reabsorption of magnesium (see hereditary hypoMg) acute or chronic alcoholic intoxication Hypophosphatemia, hypercalcemia Medications (diuretics, cisplatin, aminoglycosides, pentamidine, ciclosporin) Dialysis with a solution poor in magnesium
Endocrinopathies	Primary hyperparathyroidism Hypoparathyroidism Insulinodependent diabetes mellitus Diabetic Ketoacidosis Primary hyperaldosteronism SIADH

References :

- Sztark F, Cochard JF.
Le magnésium en anesthésie-réanimation.
Conférences d’Actualités de la SFAR 1998, Elsevier, p 649-63.

Updated: March 2019