Prerenal Failure

There exist several causes of kidney failure. Acute kidney failure (ARF) caused by the problems in blood flow (the problems that affect the blood flow before it enters the kidneys) is known as prerenal failure. Acute renal failure due to the problems in the passing of urine out of the kidneys is referred to as postrenal failure while acute kidney failure due to problems with the kidney itself; resulting in the improper filtration of blood or disrupted production of urine is known as renal failure.

Acute Renal Failure

Causes
ARF is caused mainly by the inadequate blood circulation in the kidneys. As the kidneys do not receive enough blood, they cannot filter the blood properly. Atherosclerosis or hardening of the arteries due to increased fatty deposits inside the arteries can significantly reduce the blood flow towards the kidneys. Excessive consumption of diuretics as well as significantly reduced fluid intake can lead to dehydration which in turn can lead to prerenal ARF. People with heart conditions are often advised to take diuretics to prevent accumulation of fluid in the lungs. Such patients are more likely to suffer from dehydration and ARF. Severe blood loss due to a major surgery or accident leading to sudden drop in the blood pressure levels and chronic liver disease resulting in affected production of hormones that help maintain blood flow and pressure in the kidneys, severe injury or burns, sepsis (infection in the blood), hear failure or heart attack can restrict the blood flow to the kidneys and can thus cause prerenal failure. Prerenal azotemia refers to the condition where excess amount of nitrogen type compounds in the bloodstream affect the function of the kidneys and lead to the build up of waste, such as creatinine and urea.

Symptoms

• Dizziness
• Dry mouth
• Low blood pressure (hypotension)
• Increased heart rate
• Dry, lose skin
• Increased thirst
• Weight loss
• Decreased urine output
• Abdominal pain
• Pale skin
• Symptoms of liver disease like itching sensation, nausea, loss of appetite, abdominal swelling, confusion, disorientation, sweet or ammoniacal odor, etc.
• Symptoms of heart diseases like breathing difficulty (Dyspnea), increased fatigue, fluid accumulation and swelling in the extremities (edema), venous engorgement etc.
• Prerenal azotemia also exhibits above symptoms.

Diagnosis and Treatment
After examining the symptoms, the doctor may ask you to undergo blood test and urine test. Increased BUN levels in the blood and decreased nitrogen levels in the urine indicate azotemia. High BUN to creatinine ratio (20:1) and abnormal levels of urine components indicates prerenal failure (if postrenal and intrinsic renal causes of ARF are absent). Kidney function is not severely affected in the early stage of prerenal failure. It is possible to solve the problem with proper and prompt treatment. But if the problem in the blood or blood circulation is left untreated, then prolonged decrease in the blood flow to the kidneys can lead to kidney diseases or permanently damaged kidney tissues.

The treatment is focused at improving kidney perfusion (blood circulation). Correct diagnosis or detection of the exact cause of kidney failure helps determine the treatment. Effect of dehydration can be lowered by administering intravenous fluid. Other causes like infection, liver problem, heart failure need to be treated according to the types and severity of symptoms. Since output of urine increases significantly with administration of intravenous fluids, patients diagnosed with prerenal failure are advised to be admitted in hospital. Renal function improves fast with the increased output of urine.

Patients with severe symptoms are admitted in the intensive care units as they have an increased risk of heart failure or liver failure. These patients may suffer from severe infections like viral hepatitis. Patients diagnosed with prerenal failure need prompt medication in order to prevent health complications.