Polyuria is defined as a 24-hour urine output of more than 3000ml, so a 24-hour urine output of 2400ml is not polyuria. The urine output of healthy adults is 1000ml to 2000ml/24h. Polyuria can normally be caused by drinking too much water. Intravenous infusion of saline or glucose solution, drinking alcohol, taking caffeine, and the use of diuretics or dehydrating agents can increase the urine volume significantly. Psychological factors such as insomnia can also increase nocturia. Pathologic polyuria is mainly seen in diabetes mellitus and uremia. When polyuria occurs, it is recommended to consult a doctor in time, follow the doctor’s instructions for further examination, under the guidance of the doctor to clarify the cause and timely treatment.