Diminished intake

Decreased intestinal absorption – malabsorption

Extrarenal losses (primarily GI)

Renal losses

• Drugs:  ETOH, cisplatin, diuretics, aminoglycosides

• Renal disorders: RTA, tubulointerstitial disease

• Hypercalcemia

Endocrine – hyperaldosteronism, thyrotoxicosis, hypoparathyroidism

Miscellaneous – CHF, cirrhosis, pancreatitis, Bartter’s syndrome

Cardiovascular

• Tachydysrrhythmias, asystole

• Increased risk of dig. toxicity

• ECG – variable/multiple

Neurolgoic (hyperexcitability)

• MS – irritable, disoriented, psychosis

• Ataxia, seizures, nystagmus, increased DTRs

• Muscle weakness

• Cramps

• Chvostek’s and Trousseau’s signs

• Tetany

Treat underlying cause

Mild (> 1 mEq/L) – oral (Mg. oxide)

Moderate to severe (<1) or symptomatic – parenteral

• 50% MgSO4 2 gm IM
  q 2 hrs × 3 initially

• 10% solution 6 gm IV over 3 hours,
  then 10 gm over 20 hours initially