Frothy urine and swollen calves are considered to be the precursors of glomerulonephritis, lupus nephritis, diabetic nephropathy and other diseases. 1. Glomerulonephritis: mainly related to infection, immune system diseases, etc. Typical symptoms of patients include hematuria, proteinuria, edema, elevated blood pressure, etc., which can be manifested as excessive urine foam and calf swelling. 2. Lupus nephritis: belongs to a kind of autoimmune disease, which can cause patients to have proteinuria, hematuria and other symptoms. The disease leads to the increase of protein content in urine and the change of surface tension of urine, which is manifested as foamy urine. 3. Diabetic nephropathy: If you are suffering from diabetes, you need to be alert to diabetic nephropathy with foamy urine and swollen calves. Patients are also prone to high blood pressure, pallor, diarrhea, limb sensory abnormalities and other symptoms. It is suggested that there may be other reasons for the foamy urine and swollen calves, and it is recommended to actively seek medical advice and treatment under the guidance of a professional physician.