Q: My father has a kidney stone, and although it is not painful, the doctor recommended that we be hospitalized. However, I saw another patient who was in pain and sweating profusely, but the doctor only gave him some medicine and fluids. Did the doctor exaggerate my father’s condition? Dr. Wang Bin of Dongzhimen Hospital: The degree of back pain caused by kidney stones is mainly related to the size and location of the stones. If the stone rubs against the peristaltic ureteral mucosa and irritability causes ureteral spasm, the patient will feel lumbago. When the stone is located at the peristaltic ureteral junction or in the entire ureter, even a small stone is enough to cause severe back pain. The pelvic calyces are not peristaltic, and if the stone is in these areas, it will not cause colic even if it is relatively large (often found during a physical examination). In the case of more severe hydronephrosis, the pain is only a slight swelling of the lower back on the same side. Therefore, the most painful kidney stone may not be the most serious one, but it is the most urgent; and the most serious one, although not urgent, is the one that needs to be treated carefully (it may indicate poor lifestyle habits, such as low water intake; or other abnormalities in the body, such as high uric acid). Once a stone is found, regardless of whether it is painful or not, timely diagnosis and treatment is the key.