Patients with nephropathy experience low back pain, which usually manifests as a dull ache or sometimes as colic. Nephropathy usually refers to nephrotic syndrome. This disease causes an increase in the size of the kidney during the acute phase of the disease, and there is a pericardium on the outside of the kidney, which causes back pain when the pericardium is stretched during the increase in the size of the kidney. This low back pain is not manifested as a severe pins and needles pain, but a more moderate pain, which we call dull pain. Nephrotic syndrome has a series of complications, one of which is thrombosis. When a thrombus is formed in the renal vein, it will cause low back pain, which is very intense, like a knife cut, we call it colic, and is usually accompanied by flesh-eye hematuria. When a patient with nephrotic syndrome has back pain, it is necessary to improve the ultrasound and D-dimer examination of both kidneys and the blood vessels of both kidneys to clarify what causes it and then do the corresponding treatment.