Kidney failure (also called renal failure) is when the kidney is unable to filter metabolic waste from the blood. Kidney failure is usually classified as acute kidney failure (where the kidney failure occurs quickly) or chronic kidney disease (where the kidney failure occurs slowly over time).

The symptoms of kidney failure depend on its severity and whether it is acute or chronic.

The symptoms and signs of acute kidney failure start within a few hours to few days. Symptoms include decreased urine production, drowsiness, shortness of breath, tiredness, nausea, weight gain, and swelling of the legs, feet, or ankles. Seizures, confusion, and coma can occur as well. Some people with acute kidney failure do not have any symptoms and it is detected by chance with lab tests.

Chronic kidney failure, on the other hand, develops gradually over the course of weeks, months, or years. In the early stages, there are no symptoms, and laboratory tests that measure kidney function are normal. Quite early in the progression of kidney failure the ability to concentrate and dilute the urine becomes impaired. This causes more frequent urination, especially at night.

As the ability of the kidneys to function decreases below 50% of normal, other symptoms may begin to occur, such as reduced appetite, frequent urination, fatigue, and itching. Many people with chronic kidney disease have high blood pressure, which may worsen as the kidney failure progresses. The high blood pressure results, in part, from salt retention, because the kidneys are no longer able to efficiently get rid of excess salt.

As kidney function decreases to 15% or less of normal, you may develop more symptoms, including difficulty sleeping, difficulty breathing, leg cramps, vomiting, bad taste in the mouth, weight loss, and swelling or the legs, feet, or ankles. At this point, dialysis or transplant is needed.

Written and reviewed by the MediResource Clinical Team