There may be several reasons why renal failure actually occurs. As you have read before, two types/forms of this disorder exist: a chronic and gained one (a.k.a. acute renal failure). The sources of the problem vary in both cases. For instance, the obtained health condition may be the result of issues impacting the blood flow which tries to achieve the zone of kidneys. This cause is typical for patients with renal failure. In the end, dehydration (lack of water in the organism) and even serious heart failure can be noticed. Another source might be issues and disorders of the kidneys.
Various drugs can seriously hurt this organ, so one should be careful when deciding on which medicine to take. It is better to consult doctors and pay attention to the side effects. Except for the toxins, there might be something negatively impacting the outflow of urine. As urine is located in the kidneys, it explains a lot. As for the second type of illness, the major cause might be a long-term injury of this organ.