What are kidney stones? What we usually call urinary stones grow in the duct system of the kidney, not inside the flesh of the kidney parenchyma. Kidney stones are formed when some dissolved substances in normal human urine, due to various reasons, precipitate and deposit and are trapped in the kidney’s duct system and continue to grow. How are kidney stones formed and what are the causes? Kidney stone formation is mainly related to several factors, including structural abnormalities of the kidney, crystalline calcification of the kidney papillae, intrarenal infection, abnormal nutritional metabolism, dietary structure, ethnicity and geography, etc. Certain special cases of stones are related to drugs, genetics, etc. What are the symptoms of kidney stones? In fact, kidney stones may exist for a long time without symptoms when they form and grow. And larger stones may not have symptoms such as pain and discomfort. It is not true that the larger the stone, the more severe the symptoms. Episodes of severe colic in the lower back and hematuria are two common symptoms of kidney stones. Some patients may also suffer from nausea, vomiting, stopping of bowel movement and exhaustion due to gastrointestinal irritation during the attack of renal colic. What are the dangers of large kidney stones left untreated for a long time? Hazard one: cause urinary obstruction and affect kidney function. In serious cases, the whole kidney function can be lost. The serious urinary tract infection may also cause sepsis, which is life-threatening, and the infection may cause the stone to grow rapidly, which is a vicious circle. Hazard three: local injury, resulting in hematuria, inducing polyp growth, resulting in adhesions between the stone and the canal wall. Hazard 4: Carcinogenesis. Larger stones stay in a certain area, and long-term stimulation may lead to local carcinogenesis.