Acute Renal Failure

About 5% of all hospitalized patients develop acute renal failure, the sudden interruption of renal function resulting from obstruction, reduced circulation, or renal parenchymal disease. This condition is classified as prerenal, intrarenal, or postrenal and normally passes through three distinct phases: oliguric, diuretic, and recovery. It's usually reversible with medical treatment. If not treated, it may progress to end-stage renal disease, uremia, and death.

Causes

A number of serious diseases can cause the kidneys to stop working properly. You may develop acute renal failure if:

• You have lost a lot of blood. This can occur because of a serious injury or major surgery.
• You become severely dehydrated because of vomiting or overuse of diuretics.
• You have a serious heart problem, such as heart failure, heart attack, abnormal heart rhythms, high blood pressure, endocarditis, heart valve disease, or cardiac tamponade.
• You have a disease that causes kidney or liver damage, such as nephrotic syndrome, cirrhosis, lupus, or another disease that causes inflammation of the blood vessels (vasculitis).

Signs and Symptoms

• Decreased urine output, although occasionally urine output remains normal
• Fluid retention, causing swelling in your legs, ankles or feet
• Drowsiness
• Shortness of breath
• Fatigue
• Confusion
• Seizures or coma in severe cases
• Chest pain related to pericarditis, an inflammation of the sac-like membrane that envelops your heart

Diagnostic tests

Blood test results indicating acute intrarenal failure include elevated blood urea nitrogen, serum creatinine, and potassium levels, and low blood pH, bicarbonate, hematocrit, and hemoglobin levels.

Urine specimens show casts, cellular debris, decreased specific gravity and, in glomerular diseases, proteinuria and urine osmolality close to serum osmolality. The urine sodium level is less than 20 mEq/L if oliguria results from decreased perfusion and more than 40 mEq/L if it results from an intrarenal problem. A creatinine clearance test measures the glomerular filtration rate and allows for an estimate of the number of remaining functioning nephrons.

An electrocardiogram (ECG) shows tall, peaked T waves; a widening QRS complex; and disappearing P waves if hyperkalemia is present.

Other studies used to determine the cause of renal failure include kidney ultrasonography, plain films of the abdomen, kidney-ureter-bladder radiography, excretory urography renal scan, retrograde pyelography, computed tomography scans, and nephrotomography.

Treatment

Supportive measures include a diet high in calories and low in protein, sodium, and potassium, with supplemental vitamins and restricted fluids. Meticulous electrolyte monitoring is essential to detect hyperkalemia. If hyperkalemia occurs, acute therapy may include hypertonic glucose-and-insulin infusions and sodium bicarbonate - all administered l.V. - and sodium polystyrene sulfonate (Kayexalate) by month or enema to remove potassium from the body.

If measures fail to control uremic symptoms, the patient may require hemodialysis or peritoneal dialysis. Early initiation of diuretic therapy during the oliguric phase may benefit the patient.

Prevention:

Treating any causative disorders may help to prevent acute renal failure. Many cases may not be preventable.