How are serum potassium levels determined?

Updated: Jun 20, 2018
  • Author: Eleanor Lederer, MD, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Potassium is predominantly an intracellular cation; thus, serum potassium levels do not always accurately reflect total body potassium stores. Serum potassium levels are determined by the shift of potassium between intracellular and extracellular fluid compartments, as well as by total-body potassium homeostasis.

Several factors regulate the distribution of potassium between the intracellular and extracellular spaces, including glucoregulatory hormones, adrenergic stimuli, and pH. Insulin enhances potassium entry into cells, whereas glucagon impairs it. Beta-adrenergic agonists enhance potassium entry into cells, whereas beta-blockers and alpha-adrenergic agonists inhibit it.


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