Hyperkalemia

Categories:

  • 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.

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