Normally, our urine contains potassium ions because some of our blood potassium is excreted in urine, which results in urinary potassium. The normal range of urinary potassium is 25-100 mmol/L per day. If there is too much potassium in the urine, it can lead to hypokalemia, and if there is too little potassium in the urine, it can lead to hyperkalemia, so the degree of potassium in the urine is still important. The common causes of elevated urinary potassium include hyperadrenocorticism, and in addition, patients with renal tubular acidosis. Low urinary potassium is often seen in hyperaldosteronism, renal failure, and impaired renal tubular potassium excretion, which can lead to a decrease in urinary potassium. The combination of urinary potassium with blood potassium is important to assess the patient’s condition.