eMedicine Specialties > Emergency Medicine > Endocrine & Metabolic

Hyperkalemia: Differential Diagnoses & Workup

Author: David Garth, MD, Attending Physician, Department of Emergency Medicine, Mary Washington Hospital
Contributor Information and Disclosures

Updated: Aug 6, 2009

Differential Diagnoses

Hypocalcemia

Other Problems to Be Considered

Cardiac arrhythmias

Workup

Laboratory Studies

  • Potassium level - The relationship between the serum potassium level and symptoms is not consistent. For example, patients with a chronically elevated potassium level may be asymptomatic at much higher levels than other patients. The rapidity of change in the potassium level influences the symptoms observed at various potassium levels.
  • BUN and creatinine level - For evaluation of renal status
  • Calcium level - If patient has renal failure (because hypocalcemia can exacerbate cardiac rhythm disturbances)
  • Glucose level - In patients with diabetes mellitus
  • Digoxin level - If patient is on a digitalis medication
  • Arterial or venous blood gas - If acidosis is suspected
  • Urinalysis - If signs of renal insufficiency without an already known cause are present (to look for evidence of glomerulonephritis)

Other Tests

  • Continuous cardiac monitoring - Indicated for evaluation of rhythm disturbances
  • ECG is essential and may be instrumental in diagnosing hyperkalemia in the appropriate clinical setting. ECG changes have a sequential progression of effects, which roughly correlate with the potassium level.
  • ECG findings may be observed as follows:
    • Early changes of hyperkalemia include peaked T waves, shortened QT interval, and ST-segment depression (see Media files 1-2). 

      Peaked T waves in hyperkalemia.

      Peaked T waves in hyperkalemia.

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      Peaked T waves in hyperkalemia.

      Peaked T waves in hyperkalemia.



      Peaked T waves in hyperkalemia.

      Peaked T waves in hyperkalemia.

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      Peaked T waves in hyperkalemia.

      Peaked T waves in hyperkalemia.

    • These changes are followed by bundle-branch blocks causing a widening of the QRS complex, increases in the PR interval, and decreased amplitude of the P wave (see Media files 3-4). 

      Widened QRS complexes in hyperkalemia.

      Widened QRS complexes in hyperkalemia.

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      Widened QRS complexes in hyperkalemia.

      Widened QRS complexes in hyperkalemia.



      Widened QRS complexes in a patient whose serum po...

      Widened QRS complexes in a patient whose serum potassium level was 7.8 mEq/L.

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      Widened QRS complexes in a patient whose serum po...

      Widened QRS complexes in a patient whose serum potassium level was 7.8 mEq/L.

    • These changes reverse with appropriate treatment (see Media file 5). 

      ECG of a patient with pretreatment potassium leve...

      ECG of a patient with pretreatment potassium level of 7.8 mEq/L and widened QRS complexes after receiving 1 ampule of calcium chloride. Notice narrowing of QRS complexes and reduction of T waves.

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      ECG of a patient with pretreatment potassium leve...

      ECG of a patient with pretreatment potassium level of 7.8 mEq/L and widened QRS complexes after receiving 1 ampule of calcium chloride. Notice narrowing of QRS complexes and reduction of T waves.

    • Without treatment, the P wave eventually disappears and the QRS morphology widens to resemble a sine wave. Ventricular fibrillation or asystole follows.
    • ECG findings generally correlate with the potassium level, but potentially life-threatening arrhythmias can occur without warning at almost any level of hyperkalemia.
  • Cortisol and aldosterone levels - To check for mineralocorticoid deficiency when other causes are eliminated

More on Hyperkalemia

Overview: Hyperkalemia
Differential Diagnoses & Workup: Hyperkalemia
Treatment & Medication: Hyperkalemia
Follow-up: Hyperkalemia
Multimedia: Hyperkalemia
References
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Further Reading

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Keywords

hyperkalemia, high potassium level, electrolyte imbalance, sodium-potassium pump, potassium level greater than 5.5 mEq/L, acute renal failure, chronic renal failure, potassium-sparing diuretics, urinary obstruction, sickle cell disease, Addison disease, systemic lupus erythematosus, SLE, rhabdomyolysis, hemolysis, acidosis, acute digitalis toxicity, beta-blockers toxicity, succinylcholine toxicity, pseudohyperkalemia

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Contributor Information and Disclosures

Author

David Garth, MD, Attending Physician, Department of Emergency Medicine, Mary Washington Hospital
David Garth, MD is a member of the following medical societies: American Academy of Emergency Medicine and American College of Emergency Physicians
Disclosure: Nothing to disclose.

Medical Editor

Erik D Schraga, MD, Consulting Staff, Department of Emergency Medicine, Mills-Peninsula Emergency Medical Associates; Consulting Staff, Permanente Medical Group, Kaiser Permanente, Santa Clara Medical Center
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Howard A Bessen, MD, Professor of Medicine, Department of Emergency Medicine, UCLA School of Medicine; Program Director, Harbor-UCLA Medical Center
Howard A Bessen, MD is a member of the following medical societies: American College of Emergency Physicians
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Erik D Schraga, MD, Consulting Staff, Department of Emergency Medicine, Mills-Peninsula Emergency Medical Associates; Consulting Staff, Permanente Medical Group, Kaiser Permanente, Santa Clara Medical Center
Disclosure: Nothing to disclose.

 
 
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