Reversible azotemia is a significant increase in blood levels of non-protein nitrogen (NPN), such as urine toxicity, creatinine, and uric acid, called azotemia. Reducing the level of NPN by pharmacological treatment is what we call reversible. Its etiology can be caused by inadequate renal perfusion secondary to: 1) reduced cardiac output; 2) blood loss; 3) hypotension; 4) dehydration syndrome; 5) postoperative period; 6) late oncological disease; 7) ADH secretion syndrome; 8) use of vasoconstrictive drugs. Common causes of pre-renal renal failure include vomiting, diarrhea, dehydration, haemorrhage, burns, etc. It can also be seen in conditions such as severe oedema and ascites (relative blood volume deficiency).