For men with left-sided back pain, it is recommended to go to the hospital for relevant examinations to clarify the possible causes, examples are as follows: First, left kidney stones can cause left-sided back pain, if not combined with hydronephrosis, the pain is usually persistent dull pain or hidden pain, but if obstruction causes hydronephrosis, it may cause persistent severe pain or colic. Ultrasound or CT examination of the urinary system is needed to rule out the presence of stones. Secondly, tumors in the kidney, such as renal malformation tumor or renal cancer, may cause pain in the kidney area, and the pain may gradually increase with the further increase of tumor volume, and may be accompanied by symptoms such as hematuria. CT examination of the kidney area is needed to further rule out the presence of tumor. Thirdly, kidney cysts, such as cysts of large size may cause pain due to elevated renal envelope tension, usually the size and diameter of cysts causing pain are more than 4cm, usually not accompanied by hematuria and other symptoms, and need to carry out ultrasound examination of kidney to further confirm the diagnosis. Fourthly, lumbar muscle strain can also cause pain in the lower back, but it is usually not accompanied by any abnormalities in urination, and the pain is mostly aggravated when bending or strenuous activities of the lower back, and can be relieved after rest.