Renal Failure Stages and Symptoms

The kidneys are vital organs of the body that help in the removal of excess fluids as well as wastes from the blood and maintain electrolyte balance in the body. Declining function of the kidneys leads to renal failure.

Renal failure may be of two basic types – acute renal failure (acute kidney failure), which indicates sudden loss of kidney function, and chronic renal failure (chronic kidney failure) indicating loss of kidney function due to chronic kidney disease.

Image Credit: crystal light/Shutterstock

Image Credit: crystal light/Shutterstock

Acute renal failure stages

Acute renal failure stages can be separated into three phases:

Onset or initiating renal failure stages

This may last for hours or days.

Maintenance stage

There is a marked decrease in the glomerular filtration rate in this phase. Blood levels of creatinine, urea, potassium and other metabolites and electrolytes are raised. Urine output is lowest in this phase and there is retention of fluids leading to edema and swelling of the legs and face.

The collection of water in the lungs leads to congestion of the lungs. As the blood levels of urea and creatinine rise, there may be an affliction of the brain leading to convulsions or seizures, drowsiness, coma, and death.

A rise in blood levels of potassium may cause abnormal heart rate and rhythm and even cardiac arrest.

Recovery stage

During this phase, the renal tissues repair. There is a gradual increase in urine output and a gradual fall in blood levels of creatinine. Urine output also increases.

Symptoms of chronic renal failure

There are four phases of chronic renal failure:

Diminished renal reserve

In this phase, the GFR drops to around half of its normal level. Blood levels of creatinine and blood urea nitrogen (BUN) may remain normal.

Renal insufficiency

In this stage, the GFR may drop up to 20% of its normal value further decreasing renal efficiency to filter the blood of wastes and maintain fluid and electrolyte balance.

There may be symptoms of anemia and high blood pressure. Renal insufficiency starts after more than half of the kidney function is lost. Urine becomes copious and less concentrated and contains traces of proteins and blood cells.

Related: Renal Failure Types

Renal failure

This condition is said to occur when GFR falls below 20% of normal. There is metabolic acidosis or a fall in blood pH, edema, and high blood levels of potassium.

The kidneys also regulate calcium and vitamin D balance. Decreased levels of active vitamin D in renal failure lead to a decrease in intestinal absorption of calcium. This raises levels of parathyroid hormone.

Long-term renal failure leads to loss of bone mass called renal osteodystrophy. It is usually seen in advanced renal failure or in End-stage renal disease (ESRD).

Renal failure patients also have deficiencies in coagulation factors that may raise the tendency of bleeding. This could delay blood clotting and lead to nose bleeds, heavy menstrual bleeding, gastrointestinal bleeding, excessive bruising of the skin even on minor trauma, et cetera.

End-stage renal disease or ESRD

This is a condition where the kidney functions are almost totally lost with GFR less than 5% of normal. The renal tissues appear atrophied or dried up along with fibrosis. Dialysis or transplantation of a healthy donor kidney is required for living at this stage.


Last Updated: Jan 12, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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