Hypokalemia

Background

• Low = <3.5meq/L
• Low! = <2.5meq/L

Clinical Features

• CNS
  • Weakness
  • Cramps
  • Hyporeflexia
• GI
  • Ileus
• Renal
  • Met alkalosis
• CV
  • PACs/PVCs
  • Bradycardia or atrial/junctional tachycardia
  • AV block
  • V tach, V fib

Diagnosis

• ECG findings:
  • ST seg depression
  • U wave (V4-V6)
  • QT prolongation

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
    • Diuretics
    • Hyperaldo
  • Exercise
    • HyperCa
    • HypoMg
• Drugs
  • PCN
  • Lithium
  • L-dopa
  • Theophyline

Treatment

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

• Usual dose is 40meq IV or PO unless level is <2.5. If so, both forms should be given
• 10meq will raise serum level by 0.1
• Intravenous K+ typically runs at 10meq/hour, burns when infused, and may cause phelbitis/sclerosis if run faster
• Oral K+ more quickly absorbed and preferred
• KCl elixir easily swallowed, but tastes terrible, KDur oral tablet is large and hard to swallow

See Also

Electrolyte Abnormalities (Main)

Source

• Tintinalli