Foam in the urine after the swelling of micronephrosis has subsided may be caused by physiological reasons, or it may be caused by pathological factors such as urinary protein has not been completely transformed into negative or urinary protein has increased again. 1. Physiological reasons: drinking too little water leads to urine concentration, holding urine for a long time leads to urinary urgency, etc. Foam may appear in the urine, the size of the foam varies, and quickly dissipate, it is a normal phenomenon, usually do not need special treatment. 2. Pathological reasons: if the urine protein is not completely negative, or not properly cared for after the swelling of micronephrosis has subsided, infections and other reasons or eating too much high-protein diet leading to increased urine protein, may appear after the swelling of micronephrosis has subsided, the urine is still foamy. There may be other reasons for the foamy urine after the swelling of micronephrosis has subsided. It is recommended to go to the regular hospital in a timely manner, improve the examination to clarify the cause of the disease, and then give targeted treatment under the guidance of the doctor or treatment.