Renal hyperdensity refers to a portion of the kidney lesion that appears as a high density image relative to the normal surrounding kidney tissue. Generally speaking, the high-density shadow of the kidney can be seen on CT examination. Firstly, the most common disease that occurs clinically is kidney stone. Patients with kidney stone are sometimes accompanied by back pain, urinary frequency, urinary urgency, urinary pain and other uncomfortable symptoms. Second, there is another common cause of renal cysts accompanied by bleeding or with such high-density renal cysts, which will appear as high-density shadow of the kidney. Third, the kidney itself has bleeding condition, which will also lead to high-density shadow of kidney. Fourth, if it is a substantial renal occupancy, such as kidney cancer, it will also lead to high-density shadowing in the kidney.