If the volume of urine is low each time, then the possible causes are: first, urinary tract infection, which can occur after infection with increased frequency of urination, but not much volume of urine each time, because the mucous membrane of the urethra is congested, edematous and has increased sensitivity after infection. When storing a small amount of urine, you can produce the will to urinate, so there will be a small amount of urine each time, accompanied by the symptoms of frequent and painful urination, it is recommended to carry out a routine urine examination to confirm the diagnosis. The second, when there is a male prostate hyperplasia, can appear each urine volume is not much, and at the same time can be accompanied by urinary frequency, urinary effort, urinary weakness symptoms, because the prostate hyperplasia leads to increased resistance in the urethra, there will be poor urination, part of the urine residue in the bladder, discharge a little, so the performance of the urine volume is small, it is recommended to carry out the relevant examination of the prostate to confirm the diagnosis. Thirdly, if there are obstructive factors such as urethral stones, urethral strictures or tumors, it can lead to a small amount of urination each time, mostly accompanied by stinging pain during urination or straining to urinate, which requires a urethral examination to confirm the diagnosis. Fourth, if there is kidney failure, there can also be a decrease in small variables because the filtration capacity of the kidneys is reduced, and at the same time, there can be a large amount of water retention in the body, manifested as edema, such as facial edema or edema of the limbs, etc. It is necessary to carry out kidney function tests to identify.