What is the reference range of serum potassium?

Updated: Apr 09, 2020
  • Author: Eleanor Lederer, MD, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Potassium is the primary intracellular cation; 95-98% of the total body potassium is found in the intracellular space, primarily in muscle. Total body potassium stores amount to approximately 50 mEq/kg (3500 mEq in a 70-kg person).

Normal homeostatic mechanisms precisely maintain the serum potassium level within a narrow range (3.5-5.0 mEq/L). The primary mechanisms for maintaining this balance are the buffering of extracellular potassium against a large intracellular potassium pool (via the sodium-potassium pump), which provides minute-to-minute control, and urinary excretion of potassium, which determines total body potassium balance.

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