Hyperkalemia

Background

• High defined as >6.0 mEq/L
• Consider pseudohyperkalemia (e.g. from hemolysis)
• K+ secretion is proportional to flow rate and sodium delivery through distal nephron
  • This is how loop & thiazide diuretics cause hypokalemia

ECG

Changes NOT always predictable and sequential

• 6.5 - 7.5 mEq/L: peaked T waves, prolonged PR interval, shortened QT interval
• 7.5 - 8.0 mEq/L: widened QRS interval, flattened P waves
• 10 - 12 mEq/L: sine wave, ventricular fibrillation, heart block

Differential Diagnosis

1. Pseudohyperkalemia
   1. Hemolysis of specimen
   2. Pronged tourniquet use prior to blood draw
   3. Thrombocytosis/leukocytosis
2. Redistribution
   1. Acidemia (DKA)
   2. Cellular breakdown
      1. Rhabdomyolysis/crush injury
      2. Hemolysis
      3. Tumor Lysis Syndrome
3. Increased total body potassium
   1. Inadequate excretion
      1. Renal caused (acute or chronic renal failure-must have GFR<10)
      2. Hypoaldo
      3. Drug-induced
         1. K sparing diuretics (spironolactone), ACEI, NSAIDs
   2. Excessive intake
      1. Diet
      2. Blood transfusion
4. Misc
   1. Sux, Dig, B-blockers

Treatment

1. Membrane Stabilization
   1. Give if ECG changes or consider if K+ >7
   2. Calcium (only if QRS wide)
      1. Can give as calcium gluconate or calcium chloride
         1. Calcium Gluconate 2-3g
            1. Only 1/3 the calcium as compared to chloride
            2. Must give over 10min (otherwise hypotension due to osmotic shift)
         2. Calcium Chloride 1g
            1. Can be given as slow IVP over 1-2min
            2. 3x the amount of calcium
            3. Extravasation is bad - use a good IV
      2. Duration of action = 30-60min
      3. Caution in dig-toxic pts
      4. May require multiple doses for effect (esp w/ gluconate)
2. Intracellular shift
   1. Insulin/Glucose
      1. 10 U insulin IV w/ 1-2 amp D50 IV now (unless BS already >300)
      2. Duration of effect = 4-6h
   2. Albuterol neb 5-20mg
      1. Response is dose-dependent
      2. Duration of action = 2hr
      3. Peak effect at 30min
      4. Duration of effect = 2-4hr
   3. Bicarb 1 amp IV (over 5 min)
      1. Duration of effect = 1-2hr
      2. Consider if pt is acidemic
3. Removal
   1. Lasix 40-80mg IV
   2. Volume expansion with NS if dehydrated, TLS, rhabdomyolysis, DKA, acidosis
   3. Kayexylate 30gm PO - unreliable and slow to work (2-6hr)
   4. Dialysis

See Also

Acute Renal Failure

Source

Tintinalli

Management Severe Hyperkalemia. Crit Care Med, 2008, 36:12

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