Hyperkalemia

Aka: Hyperkalemia, Hyperkalemia Related EKG Changes

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II. Pathophysiology

  1. See Potassium Homeostasis
  2. See Genetic Syndromes Affecting Serum Potassium and Blood Pressure
  3. Images
    1. potassiumHomeostasis.png

III. Epidemiology

  1. Prevalence
    1. General population: 3.3%
    2. Emergency Department: 3.6%
    3. Chronic Kidney Disease: 18%
    4. Inpatient: 6.9 to 12.3%
    5. Brookes (2021) Intern Med J 51(11): 1906-18 [PubMed]
    6. Kovesdy (2018) Eur Heart J 39(17): 1535-42 [PubMed]
    7. Singer (2017) Clin Exp Emerg Med 4(2): 73-9 [PubMed]

IV. Causes

  1. See Hyperkalemia Causes

V. Findings: Signs and Symptoms

  1. Symptoms occur when Serum Potassium > 6.0 to 6.5 meq/L
  2. Neurologic Changes
    1. Weakness
    2. Paresthesias
    3. Areflexia
    4. Ascending paralysis
    5. Respiratory Failure
  3. Cardiovascular Changes
    1. Bradycardia to Asystole or Ventricular Fibrillation
    2. AV prolonged transmission to complete Heart Block

VI. Labs

  1. Chemistry Panel
    1. Serum Potassium
    2. Serum Electrolytes including serum bicarbonate
    3. Renal Function tests (BUN, Creatinine)
  2. Spot urine for Urine Potassium, Urine Sodium and Urine Creatinine
    1. Fractional Excretion of Potassium
    2. Transtubular Potassium Gradient
    3. Urine Sodium <25 mEq/L suggests decreased distal renal flow
      1. See Hyperkalemia Causes
  3. Other labs to consider (see evaluation below)
    1. Serum Aldosterone
    2. Serum renin

VII. Diagnostics: Electrocardiogram

  1. General
    1. EKG changes occur when Serum Potassium >6.0 meq/L
      1. EKG may however be normal despite significant Hyperkalemia
      2. When significant EKG changes are present, pursue aggressive Hyperkalemia Management
    2. Changes are listed in the classic, textbook description
      1. However, patient's EKG findings often fail to follow the typical pattern
  2. Initial
    1. T Waves peaked or Tented (increased amplitude) in V2, V3, II, III
  3. Next
    1. ST depression
    2. First degree AV Block (PR Interval increases)
    3. QT Interval shortening
  4. Next (ominous harbinger)
    1. QRS Duration widening (>110 msec)
    2. Loss of P Wave (Junctional Rhythm)
    3. Sine Wave appearance
    4. New Bundle Branch Block
  5. Final
    1. Biphasic wave (sine wave) QRS and T fusion
    2. Severe Bradycardia
    3. Imminent Asystole, Ventricular Tachycardia or Ventricular Fibrillation
  6. Changes exacerbated by
    1. Hyponatremia
    2. Hypocalcemia
    3. Metabolic Acidosis
    4. Hypermagnesemia
    5. Chronic Renal Failure with frequent, recurrent Hyperkalemia
      1. Change from normal EKG to Cardiac Arrest may be rapid in these patients

VIII. Evaluation: Non-Renal Causes (transcellular shift, Potassium load, Pseudohyperkalemia)

  1. Serious signs of Hyperkalemia present (EKG, symptoms)
    1. Urgent Hyperkalemia Management
  2. Consider Pseudohyperkalemia
    1. Consider confirmatory testing (re-draw sample)
  3. Consider exogenous source or transcellular shift
    1. See Hyperkalemia Causes
    2. Eliminate causative factors

IX. Evaluation: Decreased renal excetion

  1. Urine Sodium <25 mEq/L suggests decreased distal renal flow
    1. See Hyperkalemia Causes
    2. Acute Kidney Injury or Chronic Kidney Disease
    3. Congestive Heart Failure
    4. Cirrhosis
  2. Urine Sodium >25 mEq/L with normal serum Aldosterone
    1. Primary tubular defects (e.g. RTA-4)
    2. Obstructive uropathy
    3. Tubular unresponsiveness to Aldosterone (e.g. SLE, Multiple Myeloma, Sickle Cell Anemia)
    4. Medications (e.g. Potassium sparing Diuretics, Lithium, Trimethoprim)
  3. Urine Sodium >25 mEq/L with low serum Aldosterone and normal serum renin
    1. Primary Adrenal Insufficiency
    2. Medications (Heparin, Cyclosporine, ACE Inhibitor, ARB)
  4. Urine Sodium >25 mEq/L with low serum Aldosterone and low serum renin
    1. Hyperglycemia
    2. Primary renal tubular defects
    3. Medications (e.g. NSAIDs, Beta Blockers)

X. Management

  1. See Hyperkalemia Management

XI. References

  1. Gibbs in Marx (2002) Rosen's Emerg Med, p. 1730-1
  2. Klahr (2001) in Noble (2001) Primary Care p. 1359-62
  3. Kim (2023) Am Fam Physician 107(1): 59-70 [PubMed]
  4. Viera (2015) Am Fam Physician 92(6): 487-95 [PubMed]

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