Hypokalemia

Background

Low = <3.5meq/L

Low! = <2.5meq/L

Diagnosis

• CNS
  • Weakness
  • Cramps
  • Hyporeflexia
• GI
  • Ileus
• Renal
  • Met alkalosis
• CV
  • ECG findings:
    • ST seg depression
    • U wave (V4-V6)
  • Also may cause:
    • PACs/PVCs
    • Bradycardia or atrial/junctional tachycardia
    • AV block
    • V tach, V fib

DDX

• Shift
  • Alkalosis (each 0.10 rise in pH causes 0.5 decrease)
  • Insulin
  • B-agonist
• Decreased intake
• Increased loss
  • GI (v/d/fistula)
  • Renal
    • Primary (hyperaldo, osmotic diuresis)
    • Secondary (diuretics, malignant HTN, renal art stenosis)
    • Misc
      • Licorice
      • HyperCa
      • HypoMg
      • RTA
      • Leukemia
• Drugs
  • PCN
  • Lithium
  • L-dopa
  • Theophyline

Treatment

• 20meq/h KCl IV or PO
  • every 10meq should inc serum by ~0.1meq/L)
• Treat hypomag if present

Source

Tintinalli