Patients with kidney stones cause back pain for two reasons: 1. Kidney stones cause obstruction of the renal pelvis outlet, and the urine produced by the kidneys accumulates within the kidneys, forming hydronephrosis. When the amount of fluid accumulation gradually increases, the pressure inside the renal pelvis gradually rises, at which point the symptoms of low back pain can appear. The higher the pressure, the more severe the pain. This is especially true for acute obstruction, which can cause significant pain, called renal colic. 2, because of kidney stones combined with infection, there will be inflammatory reactions in the mucosa of the renal pelvis, which can lead to symptoms of low back pain. Patients always feel intermittent or persistent low back pain, accompanied by frequent and urgent urination, and can also be accompanied by systemic inflammatory reactions and changes such as increased body temperature. The combination of the above two factors will lead to low back pain.