Normally, foamy urine is a result of very low surface tension of urine, which forms fewer bubbles. Urine contains some organic and inorganic substances, which makes some bubbles appear due to the high tension of urine. However, when the composition in urine changes due to various reasons, the surface tension of urine increases and bubbles increase. Foam in urine is common in the following cases: 1. In liver and kidney diseases, the content of bilirubin or protein in urine increases, the surface tension of urine increases, and more bubbles can be produced during urination; 2. Bladder diseases such as cystitis and bladder cancer, or other urinary tract infections, make the composition of urine easily change and produce bubbles; 3. In diabetes, the content of urinary sugar or urinary ketone bodies in urine increases, the pH of urine changes, and the surface tension of urine increases. change, the surface tension of urine increases; 4, when there are gas-producing bacteria in the urinary tract, bubbles can be produced in urine; 5, couples separated for a long time, stop sex for too long; frequent sexual excitement, due to the increased mucus secreted by the urethral bulb gland, the surface tension of urine increases, there will also be more bubbles in urine. In addition, when urination is urgent, the pressure of urination increases, the speed of urination increases, so that the surface tension of urine increases, and more bubbles are also seen.