Patients with kidney stones can have foamy urine because there may be a small amount of red and white blood cells in the urine with kidney stones, which increases the viscosity of the urine and can produce more foam when the urine is shaken with water during urination, or because the stones are combined with urinary tract infections, which can also increase the foam in the urine. However, foamy urine is not unique to kidney stones, as many other diseases can also cause foamy urine, such as kidney disease, which can increase the amount of protein in the urine, and many tiny bubbles can be seen during urination. When there is an acute infection of the urinary tract, the urine is filled with a large number of bacteria and their bacterial metabolites, and the urine color is cloudy, and the phenomenon of foam can also occur. Foam can also appear in the urine of patients with over-concentrated urine and diabetes, so it is recommended to go to the hospital for further examination to clarify the cause of frothy urine and to actively treat kidney stones.