Hyperkalemia

• Definition: Serum Potassium >5.0 mEq/L
• General
  • Renal impairment (decreased renal excretion)
    • Type IV RTA
    • Hypoaldosteronism, AKD, CKD (Renal failure w/oliguria or GFR <15)
  • Intracellular space circulation impairment (Acid-base, illness, medication)
    • Uncontrolled hyperglycemia
      • Insulin Deficiency, Hyperosmolar State, DKA
    • Acidosis
    • Rhabdomyolysis, Hematoma, Trauma
    • Tumor lysis syndrome if cancer patient
    • Drugs causing Hyperkalemia:
      • Non-selective BB – inhibits beta-2-mediated intracellular potassium uptake
        • Labetalol
      • ACEI, ARBs – inhibit ATII and AT1 receptor, decreased aldosterone secretion
      • K+ sparing diuretics – inhibits aldosterone or the ENaC channel
        • Amiloride, triamterene switch to amlodipine (f/u in 1 week)
        • Spironolactone, eplerenone
      • Digitalis/Digoxin – inhibition of the Na-K-ATPase pump
      • Cyclosporine/Tacrolimus – blocks aldosterone activity
      • Heparin – blocks aldosterone production
      • NSAIDs – decreases renal perfusion resulting in decreased K+ delivery to CD
      • Trimethoprim (increased Creatine, inhibits secretion), TMP/SMX
        • Pentamidine, Ketoconazole, IV Penicillin G
      • Succinylcholine – causes extracellular leakage of potassium through AchR
      • pRBC transfusions
      • Normal Saline (Hyperchloremic Metabolic Acidosis)
  • Increased Intake
    • Bananas, melons, citrus juice, potatoes
    • Salt substitutes
  • Pseudohyperkalemia (hemolyzed blood sample)
    • Transient, insignificant elevation in K+ levels prior to sampling
    • Hemolysis, Repeated fist clenching, Severe leukocytosis or thrombocytosis, Delayed sample processing
• Symptoms:
  • Palpitations, syncope, SCD
    • Cardiac Arrythmias, bradycardia
  • No AMS or seizures
  • Severe, ascending muscle weakness
    • +/- flaccid paralysis, hypoventilation
  • EKG
    • First: Increased T-wave amplitude, “peaked” T-waves
      • Prolonged PR, loss of P waves
    • Late: Widening QRS, sine wave pattern
      • Conduction block ectopy
      • Can progress to sinus bradycardia, sinus arrest, Vfib
• W/U (if unknown cuase):
  • Urine K+ Excretion, Plasma renin, serum aldosterone, serum cortisol, EKG
  • Trans-tubular K+ gradient (TTKG)
    • Not commonly utilized anymore
    • TTKG = (Urine K/Serum K) / (urine osmol/serum osmol)

      • 10: appropriate increase in renal excretion

      • <7: Aldosterone deficiency or resistance
  • Measure CK and LDH for lysis
  • +/- Random cortisol/ACTH stim tests
• Management
  • 1) Get EKG
    • Mild: 5.0-5.9 w/o EKG changes
      • Loop or Thiazide diuretics + LR
      • Discontinue ACEIs/Spironolactone (treat reversible causes)
    • Moderate: 5.0-5.9 w/EKG changes or 6.0-6.4 w/o EKG changes
      • IV Lasix (60-160mg) followed by LR
    • Severe: K ≥6.5-7.0, EKG changes, or Cardiac Toxicity
      • 1) Evaluate Volume Status
        • Low: A
        • Otherwise: C
      • A) If hypovolemic and needing volume resuscitation
        • Target euvolemia with a bicarb of 24-28mM
        • Low Bicarb (metabolic acidosis): Isotonic Bicarb (D5W with 150 mEq/L sodium bicarb aka 3 amps of bicarb)
          • Will likely need 1-2L (dose by dividing bicarb deficit by 150 to estimate number of needed liters)
          • Rate of 500-1000ml/hr
          • Decreases K by: dilution, shifting, and excretion
        • Normal/High bicarb (No acidosis): LR or plasmalyte/Normosol
        • NO Normal Saline
      • B) Temporizing measures
        • Cardiac Membrane Stabilization (prevents arrhythmias)
          • Always given if K >6.5 or EKG changes
          • Only lasts 30-60 minutes, may need to be re-dosed
            • HyperK is more dangerous than hypercalcemia
          • 1) IV Calcium Gluconate (3g) peripherally over 10 minutes or Calcium Chloride (1g) over 10minutes/slow push
        • Rapidly acting treatment options
          • 1) 5U IV Insulin bolus followed by Glucose
            • If glucose <250 give 2 amps D50W < D10W 500mL infusion over 2 hours

            • 250 may hold dextrose

            • Finger stick glucose for 4-6 hours
            • Lasts a few hours
        • +/- Beta 2 agonists (Albuterol) 10-20mg nebulized, likely continuous neb
        • +/- Sodium Bicarbonate (if metabolic acidosis too)
        • +/- IV Epinephrine
          • Great for hyperkalemia induced bradycardia
      • C) Elimination
        • Removal of potassium from the body slowly
        • Diuretics (furosemide or thiazides)
          • If near normal renal function: 60-120mg IV lasix
          • Near Dialysis: 80-160mg IV Lasix + (500-1000 IV chlorothiazide or PO 5-10mg metolazone) + 250-1000 acetazolamide PO/IV
            • Nephron bomb if all at max doses
          • +/- 0.2mg fludrocortisone
            • Works for all except obstructive uropathy, transplants, most drugs, SLE, sickle cell
            • Best for ACEI/ARBs/NSAIDs
          • Give balanced crystalloid to prevent hypovolemia
            • LR or isotonic bicarb
        • Dialysis if failure
      • D) Elimination
        • Cation exchange resins
          • Sodium polystyrene sulfonate (Kayexalate)
            • Promotes Na+/K+ exchange in intestine, increased in stool
            • SE: Intestinal necrosis
            • CI: Post-op patients
          • Sodium Zirconium cyclosilicate (Lokalema)
            • 0.2mM reduction within 4 hours, 0.4mM reduction in 24 hours
        • Doesn’t work for anuric patients - Mildly effective, may prevent or delay dialysis - 10mg PO q8hrs
• References
  • 2007091017: Choi M, Ziyadeh F. The utility of the transtubular potassium gradient in the evaluation of hyperkalemia. J Am Soc Nephrol 2008; 19:424–426.