Some nephritis can cause lumbago, such as acute nephritis, acute progressive nephritis, lupus nephritis, etc. Nephritis causes lumbago mainly because the kidney volume increases in the acute stage of nephritis, which stretches the kidney envelope and stimulates the local nerves, which will cause lumbago. The more common nephritis that can cause an increase in kidney volume are the three types of nephritis mentioned above. Chronic nephritis, which is often mentioned, usually does not cause lumbago because the disease is more moderate in its onset and slower in its progress, and usually does not cause an increase in kidney volume, so it does not cause lumbago. When patients have back pain, they should observe whether the color of urine turns red and whether there is foam, perform routine urine examination to observe whether there are red blood cells and urine protein, and improve the ultrasound examination of both kidneys to observe whether the volume of the kidneys increases. Through these tests and clinical manifestations, we can determine what type of nephritis it is, and then decide the next treatment plan.