Urine dark yellow, possible causes and treatment: 1. If you drink less water then urine may appear concentrated, or if you have not urinated for a long time and urine is stored in the bladder for too long, then urine will also appear dark yellow in color. At this time, there are usually no symptoms of urinary tract irritation and no symptoms of discomfort in urination. It is recommended to drink more water appropriately to supplement water intake and observe whether the color of urine has changed.2. Patients with abnormal bilirubin, for example, can also experience concentrated, yellowish urine. Because bilirubin is excreted by the kidneys after dissolving in water, this causes a yellowish stain in the urine, along with a yellowish stain of the skin or sclera, it is recommended to keep the urine for routine urine examination. If the bilirubin level is elevated, further blood bilirubin checks are needed to treat jaundice.3. Food or drug staining, such as oral vitamin B, can produce riboflavin, which is excreted by the kidneys, causing the urine to appear dark yellow. In this case, the color of urine can return to normal after stopping the relevant medication or food.