Pre-renal and post-renal are generally relative to patients with acute renal failure. Pre-renal factors often refer to inadequate renal perfusion caused by various reasons, such as gastrointestinal bleeding or hemorrhagic shock, severe burns, dehydration, etc. will lead to a decrease in blood volume, which will cause inadequate renal perfusion, that is, the volume of blood flowing through the kidneys will also decline, leading to renal ischemia, hypoxia caused by renal injury. Post-renal factors often refer to obstruction of the urinary system, resulting in urine not being able to pass out of the body smoothly, thus causing hydronephrosis and renal failure. In addition, nephrogenic factors refer to problems in the kidneys, such as acute tubular necrosis or interstitial lesions.