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For further information, see CMDT Part 21-05: Hyperkalemia
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Essentials of Diagnosis
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Serum potassium level > 5.2 mEq/L (5.2 mmol/L)
Check medications carefully; hyperkalemia may develop from angiotensin-converting enzyme (ACE) inhibitors, angiotensin-receptor blockers and potassium-sparing diuretics, most commonly in patients with kidney dysfunction
ECG may be normal despite life-threatening hyperkalemia
Rule out pseudohyperkalemia and extracellular potassium shift from cells
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General Considerations
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Hyperkalemia is a rare occurrence in healthy individuals due to adaptive mechanisms designed to prevent accumulation of potassium in the extracellular fluid, mainly via rapid urinary excretion
Persistent hyperkalemia generally requires an impairment in renal potassium excretion due to
Impaired secretion of or hyporesponsiveness to aldosterone
Impaired delivery of sodium and water to the distal nephron
Kidney disease (acute or chronic)
Transient hyperkalemia suggests shift of potassium from inside cells into the extracellular fluid, which can occur in the context of
Pseudohyperkalemia is a laboratory artifact in which there is an elevation in serum potassium levels in the absence of true electrolyte imbalance as a result of
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Symptoms of hyperkalemia are a consequence of impaired neuromuscular transmission
Potassium concentrations above 7 mEq/L may cause cardiac conduction abnormalities and neuromuscular manifestations, such as muscle weakness, which may be profound
Hyperkalemic period paralysis
Hyperkalemia additionally impairs urinary ammonium excretion and may lead to metabolic acidosis
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Diagnostic Procedures
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The rapidity in development of hyperkalemia may correlate with the development of ECG changes
Typical sequential changes
As the QRS continues to widen, sine waves may develop, which are concerning for imminent ventricular fibrillation and ultimately asystole
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Exogenous sources of potassium should be eliminated
Medications that can impair potassium excretion should be discontinued
Volume depletion should be corrected
Metabolic acidosis, if present, should be improved
Treatment of hyperkalemia is outlined in Table 21–5
In emergency ...