At what serum potassium concentration is hyperkalemia (high serum potassium level) diagnosed?

Updated: Apr 09, 2020
  • Author: Eleanor Lederer, MD, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Hyperkalemia is defined as a serum potassium concentration higher than the upper limit of the normal range; the range in infants and children is age-dependent, whereas the range for adults is approximately 3.5-5.5 mEq/L. The upper limit may be considerably higher in young or premature infants, as high as 6.5 mEq/L. [5] Degrees of hyperkalemia are generally defined as follows (however, note that not all sources agree on these levels) [6] :

  • 5.5-6.0 mEq/L – Mild
  • 6.1-7.0 mEq/L – Moderate
  • ≥7.0 mEq/L – Severe

Levels higher than 7 mEq/L can lead to significant hemodynamic and neurologic consequences. Levels exceeding 8.5 mEq/L can cause respiratory paralysis or cardiac arrest and can quickly be fatal.

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