By Dr Ananya Mandal, MD
The kidneys are vital organs of the body that help in the removal of excess fluids as well as wastes from blood and maintain electrolyte balance in the body. Declining functions of the kidneys lead to renal failure.
Renal failure may be of two basic types – acute renal failure, which indicates sudden loss of kidney function, and chronic renal failure indicating loss of kidney function due to chronic kidney disease.
Symptoms of acute renal failure
There are three phases of acute renal failure:-
Onset or initiating phase
This may last for hours or days.
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 legs and face.
Collection of water in the lungs leads to congestion of the lungs. As the blood levels of urea and creatinine rise, there may be affliction of the brain leading to convulsions or seizures, drowsiness, coma, and death.
Rise of blood levels of potassium may cause abnormal heart rate and rhythm and even cardiac arrest.
During this phase the renal tissues repair. There is gradual increase in urine output and 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.
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 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 contain traces of proteins and blood cells.
This condition is said to occur when GFR falls below 20% of normal. There is metabolic acidosis or 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 leads 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 etc.
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.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)