The fine dusty substance in the urine may be caused by factors such as urine concentration, urinary tract infections and kidney diseases. 1. Concentration of urine: drinking too little water or sweating more, resulting in less water in the urine, the content of other substances increased, you will find that there is a fine dusty substance in the urine, and the urine will be yellow, accompanied by a strange odor. 2. Urinary tract infections: for example, cystitis or urethritis, may be associated with prolonged periods of drinking too little water or poor hygiene, so that the presence of purulent substances in the urine, which can lead to fine dusty substances in the urine, accompanied by frequent urination, urinary urgency, urinary pain and other symptoms. 3. Kidney disease: such as glomerulonephritis, may lead to impaired function of the kidneys, there will be protein into the urine, which may cause the urine to have a fine dusty substance, may also be accompanied by lower extremity edema, hematuria and other symptoms. If there is a fine dusty substance in the urine, accompanied by symptoms such as discomfort in urination, it is recommended to consult a doctor as soon as possible.