Patients with less urine are considered to be caused by the following reasons: 1. Considered to be prerenal oliguria, a condition in which the amount of blood filtered through the kidneys as well as the amount of body fluids is reduced, resulting in a decrease in urine volume, usually due to a large loss of blood, a large loss of body fluids, less hydration, traumatic shock, heat stroke, etc., resulting in insufficient renal perfusion and oliguria. 2. Considered to be caused by the kidneys themselves The causes of hyponatremia include acute glomerulonephritis, glomerulonephritis, loss of renal filtration function, uremia, etc. 3. Consider hyponatremia caused by post-renal obstruction, including various urinary tract stones, urinary tract tumors, prostatic hyperplasia and other diseases. The above is an analysis of some of the causes of oliguria in patients, and it is recommended that patients should go to a regular hospital for relevant examinations to clarify the diagnosis if their urine volume is too low for a long time.