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.