Urine yellow, foamy and smelly children consider urinary tract infections, concentrated state of urine, diseases that cause high concentration of solutes in the urine and other conditions. 1. The most common cause of smelly and frothy urine is urinary tract infection. Various causes of cystitis, urethritis, prostatitis, etc. can make the urine contains more bacteria and other pathogenic microorganisms, pathogenic microorganisms themselves and metabolic products can lead to cloudy urine, urine odor and foam. 2. Foam can also appear when the urine is in a concentrated state, but it will soon dissipate, and the color of the urine will deepen. Normally, there is no odor. At this time, you only need to drink more water, the above symptoms will disappear. 3. Diseases that lead to high concentration of solutes in the urine: such as diabetes mellitus, which can lead to increased sugar in the blood, resulting in osmotic diuresis, and contains more foam. There may be other reasons for yellow urine with foam and odor, and it is recommended to consult a doctor in time.