The amount of urine is constant under normal circumstances, and adults urinate about 1-2 liters per day. There are physiological cases of low urine volume and pathological cases of low urine volume. 1, the physiological case of less urine, due to drink less water, eat more spicy fire and caused. In hot weather, a lot of sweating, water evaporates through the skin, so the urine excreted by the kidneys will become less. This situation can be slowly relieved by paying attention to drinking more water and keeping the surrounding environment cool. 2. Pathological oliguria. The daily urine volume below 400 ml is considered oliguria. (1) Pre-renal causes: heart failure, shock, insufficient blood volume due to dehydration. (2) Renal oliguria, various glomerulonephritis, interstitial kidney disease caused by hypofiltration function, resulting in oliguria. (3) Post-renal oliguria, which is caused by obstruction due to urinary tract stones or tumors, resulting in difficulty in urination. Pathological causes should be treated actively, and oliguria is a more serious symptom. Less than 100 ml of urine per day is called anuria. If not actively treated it is likely to cause damage to kidney function. You should pay attention to the color of urine, its nature, and the volume of urine, and go to the hospital if you feel uncomfortable.