Hypomagnesemia

Categories: mcspages

Hypomagnesemia

  • Magnesium <0.7-1.3/1.6
    • PTH release is impaired <1mg/dl
  • Causes
    • Most commonly caused by chronic combo of (impaired intestinal absorption and increased renal excretion):
      • Impaired absorption
        • Malabsorption, Diarrhea, Pancreatitis
        • Omeprazole, Foscarnet
        • Alcoholism, NG suction
      • Increased Excretion
        • Loop and Thiazide diuretics
        • SIADH
      • Medications
        • Aminoglycosides, Amphotericin B, Cisplatin, Cyclosporine, Pentamidine, PPIs
      • Other
        • Prolonged fasting, fistulas, TPN, diuretics, Bartter Syndrome, frugs, renal transplant, post-Parathyroidectomy, DKA, lactation, burns, pancreatitis
        • Aminoglycosides, AMP B, Cisplatin, Cyclosporine, Pentamidine, PPIs
        • Hypoparathyroidism (normal or low serum phosphate)
  • Symptoms
    • Lethargy, confusion, tremor, ataxia, nystagmus, tetany, seizures
    • Atrial and Ventricular arrhythmias
      • Especially if on digoxin
    • Neuromuscular irritability and tetany with weakness
    • Delirium and coma
    • EKGs
      • PR and QT prolongation
      • Widened QRS
      • T wave flattening
      • Torsade de pointes if severe
  • Labs
    • Refractory Hypocalcemia
    • Refractory Hypokalemia
      • Renal potassium wasting
        • Excess potassium efflux from renal tubular cells
  • Testing
    • Urine Mg >2/24hrs or FEMg >2%: Increased Renal Excretion
  • Treatment
    • Max rate 2g Mg Sulfate/hr, recommended 1g Mg Sulfate/hr
      • 10% solution over 10minutes followed by 1g in 100ml/hr
    • Oral unless symptomatic
    • Serum 1.9-2: IV 1g Mg Sulfate, recheck in AM
    • Serum 1.7-1.9: IV 2g Mg Sulfate, recheck in AM
    • Serum 1.6-1.7: IV 3g Mg Sulfate, recheck in 4-6hrs if symptomatic, otherwise AM
    • Serum <1.5:
    • Monitor DTRs, rebound hypermagnesemia will have hyporeflexia

results matching ""

    No results matching ""