Early stage of left renal cyst may have no symptoms, but when the cyst increases and presses the surrounding tissues, it will cause left side lumbar and abdominal discomfort, hematuria, proteinuria, abdominal mass and others. 1. Left-sided lumbar and abdominal discomfort: mostly lumbar and abdominal discomfort or dull pain, which may radiate to the lower part and back. 2. Hematuria: when the cyst compresses the surrounding renal tissues, there will be hematuria or microscopic hematuria. 3. Proteinuria: usually the urine protein content is not very high. 4. Abdominal mass: in a few cases, the mass is so big that the enlarged kidney can be touched at the waist. 5. Other: the cyst enlargement compresses the renal artery, which may cause nephrogenic hypertension and so on. Patients with left renal cysts should seek timely medical treatment under the guidance of specialists to avoid delay.