Frothy urine, lumbago may be caused by urinary stones, nephritis and other diseases, specific to go to the local hospital to promptly identify the cause. 1. Urinary stones may be caused by metabolic abnormalities, or urinary tract obstruction, infection and other factors. The main manifestation of pain in the kidney area, bloody urine or pus urine accompanied by nausea and vomiting. 2. Nephritis is a group of diseases with hematuria, proteinuria, edema, hypertension and renal function impairment as the main clinical manifestations. Among them, proteinuria may occur when the glomerular filtration membrane barrier is damaged, which is mainly manifested by the appearance of foam in the urine. Meanwhile, sodium retention due to edema can and will cause symptoms such as low back pain and lumbago. Once the above symptoms appear, you should go to the hospital immediately and follow the doctor’s instructions to standardize the treatment.