Definition: Serum Potassium (K) < 3.5 mEq/L

Causes

• Hypomagnesemia
  • From Renal Potassium Wasting – K Secreted by Potassium (ROMK) Channels That are Normally Inhibited by Magnesium
  • Relatively Refractory to Potassium Supplementation Until Magnesium is Corrected
• Hyperaldosteronism
• Refeeding Syndrome
• Hypothermia
• Renal Tubular Acidosis
• Diarrhea
• Medications:
  • Diuretics
  • Insulin
  • Albuterol (β-Agonists)
  • Antipsychotic Drugs

Severity

• Mild: 3.0-3.4 mEq/L
• Moderate: 2.5-2.9 mEq/L
• Severe: < 2.5 mEq/L

Presentation

• Mild: Mostly Asymptomatic
• Moderate: EKG Changes
• Severe: Muscle Weakness
  • May Manifest as Respiratory Depression or Ileus

EKG Changes

• Flattened T Waves
• U Waves
• ST Depression
• Prolonged QT Interval
• Premature Atrial Complex (PAC) or Premature Ventricular Complex (PVC)

Treatment

• Primary Treatment: Potassium Replacement
• Potassium Chloride (KCl) is Generally Preferred Over Potassium-Phosphate (K-Phos)
• Dose: Every 10 mEq will Increase Serum K 0.05-0.10 mEq/L
  • Goal is to Achieve the Middle of the Normal Range (4.0), Not the Lower Limit of Normal (3.5), to Allow for Ongoing Losses
  • IV and PO Dosing are Equivalent
• Route:
  • Enteral (PO) is Slower but Generally Preferred if Able to Tolerate Oral Intake
  • Intravenous (IV) is Faster are Generally Preferred if the Deficiency is Severe
• Rechecking After Replacement:
  • IV – Can Check Immediately After the Final Dose
  • PO – Should Wait One-Hour to Recheck to Allow for Absorption
• Correct Any Underlying Hypomagnesemia as Well