A lot of foam in the urine may be caused by physiological reasons such as urine concentration, and may also be pathological reasons, such as cystitis, nephrotic syndrome and other diseases caused by proteinuria. 1. Physiological reasons: drinking too little water leads to urine concentration, long time hold urine leads to urinate too fast, etc. Foam may appear in the urine, this time the foam size varies, and quickly dissipate, is a normal phenomenon, do not need special treatment. 2. Pathologic causes: (1) cystitis: due to bacterial reproduction, the composition of urine is prone to change, there will be white blood cells, bacteria and a small amount of protein in the urine, which may produce foam. (2) nephrotic syndrome: there will be a large amount of proteinuria, elevated protein content in the urine can lead to increased foam in the urine, the foam is mostly fine and lasts for a long time. Foam in urine can also be seen in primary glomerulonephritis, diabetic nephropathy and other diseases. If the patient’s urine foam, it is recommended to go to the regular hospital in time, complete the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.