There are many reasons for yellow urine, and it is not necessarily a sign of illness. And normal urine is just a pale yellow color. The causes of yellow urine include physiological factors such as low water intake. It may also be pathologic, such as liver and gallbladder diseases, urinary tract infections and so on. 1. Drinking too little water: Because urine contains more components, patients drink too little water, resulting in urine can not be diluted, there will be a dark yellow urine. In addition, the color of urine may also be affected by certain foods. 2. Liver and gallbladder diseases: such as cholecystitis, gallbladder stones, hepatitis and other liver and gallbladder diseases, can cause bilirubin elevation jaundice. Patients may have yellow urine, yellow skin and other symptoms. 3. Urinary system infections: such as bacterial urethritis, bacterial cystitis, etc., patients usually appear frequent urination, painful urination, urinary urgency, lower abdominal pain, etc., when the number of bacterial reproduction is high, yellow urine will also occur. There are many reasons for yellow urine, but it is not necessarily a sign of a specific disease. It is recommended that patients go to the hospital in time to clarify the cause of the disease and actively treat it.