Men with left-sided back pain are recommended to go to the hospital for further examination to clarify the possible causes: first, left-sided kidney stones or ureteral stones, which can cause sudden left-sided back pain, and the pain is often more intense, and the pain may be accompanied by flesh-eye hematuria, accompanied by symptoms of urinary frequency and urgency, and further ultrasound examination of the urinary system is needed to rule out the presence of stones. Second, pyelonephritis, when combined with pyelonephritis, can appear to have left-sided back pain, are accompanied by fever, accompanied by urinary frequency, urinary urgency symptoms. It may also be accompanied by hematuria and cloudy urine. Further urinalysis is needed to rule out the presence of infection. Thirdly, left-sided lumbar muscle strain or lumbar disc herniation can cause left-sided lumbago, and the pain will not be accompanied by abnormal urination, and the pain is aggravated after activity and can be alleviated after rest, which can be further differentiated from lumbago caused by urinary system-related diseases.