A small stone in the left kidney can be caused by the stone blocking the calyx of the kidney or rubbing against the renal pelvis or ureter, or it can be caused by a combination of infections. Small stones in the left kidney may block the calyces or rub against the mucous membrane of the renal pelvis or ureter by the urine, thus causing discomfort or vague pain in the lower back, which is obvious after activities. When the stone enters the ureter with urine and causes ureteral obstruction, severe ureteral colic may occur. Renal pelvic stones are very easy to be combined with infection, and the irritation of inflammatory substances after infection can also cause lumbar pain, or even develop into acute pyelonephritis or renal abscess, with chills, high fever, lumbar pain and other symptoms. When small stones are found in the left kidney, patients are advised to go to the hospital as soon as possible and take appropriate treatment in time to avoid further development of the condition.