Kidney or renal failure is a condition where the kidneys lose their normal functionality, which may be due to various factors including infections, auto immune diseases, diabetes and other endocrine disorders, cancer, and toxic chemicals. It is characterised by the reduction in the excretory and regulatory functions of the kidney. It usually occurs at the terminal stages of the disease processes. Once renal failure occurs, it requires immediate management and even then prognosis is often not good unless transplantation is done.
Cause and Pathogenesis
There are two main types of renal failure:
Acute Renal Failure (ARF)
This is characterised by sudden impairment of renal function marked by rapid, and steadily increasing azotemia (accumulation in the blood of toxic products normally excreted by the kidneys) with or without oliguria (decreased urine output).
- Prerenal factors (factors that are primarily outside the kidney and before the blood reaches the kidney) that interfere with renal perfusion (for example: fluid and electrolyte depletion, hemorrhage, severe septic infections, cardiac or liver failure, heat stroke, fluid depletion due to burns).
- Postrenal factors (factors primarily outside the kidneys after the blood leaves the kidneys) that cause obstruction (for example: enlarged prostate, renal calculi (kidney stones), tumors of the bladder or pelvis).
- Renal factors (factors within the kidney) that impair the renal function directly (for example: acute tubular injury, acute glomerulonephritis, which is an inflammatory disorder of the kidney, arterial or venous obstruction).
Chronic Renal Failure (CRF)
This is characterised by a slow, insidious, and irreversible impairment of renal excretory and regulatory function.
- Chronic disease of the kidneys (for example: glomerulonephritis)
- Chronic infection (for example: tuberculosis)
- Anomalies of the kidneys that are present since birth
- Vascular disease (for example: hypertension)
- Endocrine disease (for example: diabetes)
- Obstructive processes in the kidneys (for example: kidney stones)
- Nephrotoxins (toxic chemicals that affect the kidneys)
- Autoimmune diseases
Investigations and Diagnosis
What are the symptoms?
Acute renal failure Symptoms
Here the symptoms are largely those of the condition causing the kidney failure, such as:
- blood loss, causing a drop in blood pressure.
- vomiting and diarrhoea, causing dehydration.
- crush injuries. If large amounts of muscle are damaged there is a release of toxic protein substances that are harmful to the kidneys.
- Sudden blockage of urine drainage.
Chronic renal failure SymptomsThe damage to the kidneys is usually 'silent' and not noticed at an early stage. It may be discovered incidentally from blood or urine tests done for other reasons. High blood pressure very commonly occurs with it. Symptoms are uncommon unless kidney failure is far advanced, when any of the following may be present:
- loss of appetite
- nausea and vomiting
- fluid retention, shown as ankle swelling (oedema)
In acute renal failure, the diagnosis is aimed at classifying of the condition as prerenal, renal, or postrenal. Urine examination is done to determine the presence of protein, sugar, casts and crystals, its pH and specific gravity and the quantity of sodium. This gives an idea as to the cause of the failure.
Blood tests include tests of renal function like Blood Urea Nitrogen, Serum Creatinine, and Serum Electrolytes. The Creatinine Clearance is also an important index of renal function. Blood counts, haemoglobin levels and haematocrit values are also useful. An Ultrasound Abdomen or a CT-Scan needs to be taken to assess kidney size with grossly shrunken kidneys indicating a more advanced disease. Stones and other obstructive disorders can also be picked up by ultrasound.
Treatment and Prognosis
In ARF, general treatment measures include avoiding drugs that require renal excretion, balancing fluid intake with output, high carbohydrate and low-protein diet, essential amino acid replacement and at least 100gms of glucose per day, decreased intake of salt and potassium, vitamin supplements, prevention of injury or infection, weight management, electrolytes monitoring, and monitoring of vital signs, cardiac status, and mental status. Peritoneal or haemodialysis is the treatment of choice when other measures fail. Drugs are used to reduce the blood pressure, diuretics (drugs that increase urine output) are used in some cases to increase blood flow unless oliguria is present. Antibiotics may be needed to treat associated infections (predominantly only antibiotics excreted by the liver are used if there is no liver disease).
In CRF, general treatment measures include a diet low in sodium, potassium, and phosphate, but high in calories and supplemented with essential amino acids. Other measures include balanced fluid intake, and monitoring weight changes, vital signs, electrolyte balance, and cardiac and mental status.
Antihypertensives for hypertension, diuretics for oedema and hypertension, phosphate binders for hyperphosphatemia (increased phosphate levels in the body), antibiotics, anticonvulsants for seizures, antiemetics (drugs that prevent vomiting) for nausea, laxatives for constipation, calcium, iron, and vitamin supplements.
Peritoneal dialysis or haemodialysis is often required for end-stage disease.
What are the possible complications of renal failure?
There are many complications associated with renal failure, especially over the long-term. Some of the more common problems are heart failure, anemia, high blood pressure, electrolyte imbalances, hemorrhage, bone fractures and lowered immune response.