Potassium is the main positively charged ion inside the cells, with only a small fraction circulating in blood. That circulating fraction sets the electrical excitability of nerve, muscle and especially heart tissue. It is regulated by the kidneys and by aldosterone, so it speaks for renal and adrenal function as well as acid-base balance.
No readings for this marker yet.
Raised potassium most often reflects reduced kidney excretion, adrenal insufficiency, acidosis, tissue breakdown, or drugs that hold potassium back such as ACE inhibitors, angiotensin receptor blockers and potassium-sparing diuretics. Lowered potassium most often follows losses through vomiting, diarrhoea or loop and thiazide diuretics, and accompanies alkalosis or excess aldosterone. Both directions can disturb heart rhythm, so results outside the range are usually confirmed promptly with a doctor.
Falsely high values are common and matter: a tight tourniquet, fist clenching, difficult venepuncture, haemolysis of the sample or delayed processing all release potassium from cells. Very high platelet or white cell counts raise it in serum but not in plasma. It is read together with sodium and chloride, with kidney markers such as creatinine and eGFR, with magnesium, whose deficiency makes low potassium hard to correct, and with acid-base status.
Reference ranges are general adult values and depend on lab, assay, age and sex. For orientation, not diagnosis — discuss results with your doctor.