There are many reasons for low potassium. The most common ones are as follows:

Excessive renal excretion: excessive mineralocorticoid, Barthes syndrome, diuretics or chronic metabolic alkalosis, some antibiotics or renal tubular acidosis, acute leukemia, ureter sigmoid colon anastomosis, etc., can all cause excessive potassium excretion through the kidney, resulting in low potassium.

Gastrointestinal excretion: Vomiting and diarrhea may cause excessive potassium excretion in the gastrointestinal tract.

Extracellular to intracellular transfer: acute alkalosis, hypokalemic periodic paralysis, barium and insulin therapy, vitamin B 12 therapy, thyrotoxicosis, etc. can cause excessive potassium transfer to cells, resulting in low blood potassium concentration.