Hidden pain in the left posterior waist to be vigilant is true, considering the possible presence of renal cysts, kidney stones, nephritis, lumbar intervertebral disc herniation and other diseases. 1. Kidney cysts: after some patients have kidney cysts, the volume of kidney cysts increases, compressing the ureter and kidney, resulting in hydronephrosis, increased renal peritoneal tension, and vague pain in the back of the left side. 2. Kidney stones: clinically, kidney stones are impacted and fall into the ureter, resulting in ureteral blockage, hydronephrosis, causing renal colic, and this situation. 3. Nephritis: patients with nephritis, inflammation will lead to glomerular lesions, renal vein thrombosis volume increases, the renal envelope is involved, the left lower back pain. 4. Lumbar intervertebral disc herniation: clinically, lumbar intervertebral disc herniation lumbar vertebral tissue compression, or combined with lumbar dorsal musculoskeletal fasciitis, may lead to lumbar pain symptoms. If it is difficult to relieve the pain in the back of the left side, you need to consult a doctor in time, make a clear diagnosis, and actively cooperate with the doctor’s treatment.