Mind that there are several signs to pay attention to. At the early stages, a person might not notice any symptoms. Even health care professionals can’t figure it out. So, the initial period appears to be what they call asymptomatic. It is rather dangerous as when left without any attention; renal failure may progress and result in much-unexpected consequences.
Focus on the following warning signs: lethargy (the patient feels sleepy all the time), fatigue, exhaustion, overall body weakness, breathlessness (a person may start running out of the air), and edema. Then, add secondary symptoms: anemia, absence of appetite, sleep disorders, tiredness, congestive heart failure, problems with metabolism and digestion, hyperkalemia. The last term refers to issues with pressure (usually, high blood potassium).
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.