Renal Failure

Introduction

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). The causes of ARF include:

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).
ARF caused by prerenal or postrenal factors is more amenable to treatment than ARF caused by renal factors.

Chronic Renal Failure (CRF)

This is characterised by a slow, insidious, and irreversible impairment of renal excretory and regulatory function.

The causes of CRF include:

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





Symptoms and Signs

The symptoms and signs of renal failure depend upon the type of failure. In acute renal failure, the patient may have oliguria (reduced urine output) along with generalised swelling (oedema) of the body together with high blood pressure. Sometimes there may be blood in the urine. In the early stages of CRF, the patient may merely have increasing fatigue and tiredness and symptoms like nocturia (increased frequency of urination at night). Vomiting, oedema and high blood pressure eventually develop. There is also loss of appetite. Other symptoms depend upon the cause of the failure. For example, if there are kidney stones, then there may be excruciating loin pain or if there is severe hemorrhage or diarrhoea there may be signs of shock. Complications in renal failure include pulmonary oedema (presence of fluid in the lungs), hypertensive crisis (severe sustained increase in blood pressure), acidosis, hyperkalemia (increased level of Potassium in the blood), and infection. If untreated, the last stage of renal failure is almost invariably fatal.





Investigations and Diagnosis


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.
Drug therapy

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.
Dialysis

Peritoneal dialysis or haemodialysis is often required for end-stage disease.
Surgery

Kidney transplantation is the solution for several patients as dialysis is often a measure that cannot be indefinitely done. The results of transplantation are now extremely good with substantial five-year survival rates.

Prevention


Prevention of the causative factors, wherever possible, may help in preventing the development of the disease. Control of blood sugar in diabetics is of great importance. After the disease has developed, drug therapy may help and dialysis and kidney transplantation are increasingly being performed with excellent results. Control of blood pressure and avoiding smoking, alcohol, and drug abuse are also necessary. Proper diet and exercise are also help in delaying the progress of the disease.