Acute Kidney Failure Health Article

Definition

Acute kidney failure (AKF) occurs when there is a sudden reduction in kidney function that results in nitrogenous wastes accumulating in the blood (azotemia).

Description

The kidneys are the body's natural filtration system. They perform the critical task of processing approximately 200 quarts of fluid in the bloodstream every 24 hours. Waste products like urea and toxins, along with excess fluids, are removed from the bloodstream in the form of urine. Kidney (or renal) failure occurs when kidney functioning becomes impaired somehow. Fluids and toxins begin to accumulate in the bloodstream. As fluids build up in the bloodstream, the patient with AKF may become puffy and swollen (edematous) in the face, hands, and feet. Their blood pressure typically begins to rise, and they may experience fatigue and nausea. Often urine output decreases drastically or is not produced at all.

Unlike chronic kidney failure, which is long term and irreversible, acute kidney failure is often a temporary condition. With proper and timely treatment, it can many times be reversed, leaving no permanent or serious damage to the kidneys.

Causes and symptoms

Acute kidney failure appears most frequently as a complication of serious illness, like heart and/or liver failure, serious infection, dehydration, severe burns, and excessive bleeding (hemorrhage). It may also be caused by an obstruction to the urinary tract or as a direct result of kidney disease, injury, or an adverse reaction to medicine. These conditions divide AKF into three main categories: prerenal, postrenal, and intrinsic (inside) conditions.

Prerenal AKF does not damage the kidney, but can cause diminished kidney function and significantly decreased renal (kidney) blood flow. It is the most common type of acute renal failure, and is often the result of:

• dehydration
• extracellular fluid (ECF) volume depletion (or other acute fluid loss from the gastrointestinal tract, kidneys, or skin)
• drugs (NSAIDS, cyclosporine, radiopaque contrast materials, or any substance toxic to the kidneys)
• hemorrhage
• septicemia, or sepsis
• congestive heart failure (CHF)
• liver failure
• burns
• decreased intravascular volume (referred to as third spacing, also found in the presence of pancreatitis, post surgical patients, and patients with a nephrotic syndrome)

Postrenal AKF is the result of an obstruction of some kind somewhere in the urinary tract, often in the bladder or ureters (the tubes leading from the kidney to the bladder). The kidneys compensate to such a degree that one kidney can be completely obstructed and the other will maintain nearly normal kidney function for the body. The conditions that often cause postrenal AKF are:

• inflammation of the prostate gland in men (prostatitis)
• enlargement of the prostate gland (benign prostatic hypertrophy)
• bladder or pelvic tumors
• kidney stones (calculi)

Intrinsic AKF involves a type of kidney disease or direct injury to the kidneys. This type of AKF accounts for 20-30% of AKF reported among hospitalized patients. Intrinsic AKF can result from:

• lack of blood supply to the kidneys (ischemia)
• use of radiocontrast agents in patients with kidney problems
• drug abuse or overdose
• long-term use of nephrotoxic medications, like certain pain medicines
• acute inflammation of the glomeruli, or filters, of the kidney (glomerulonephritis)
• kidney infections (pyelitis or pyelonephritis)
• infiltration by lymphoma, leukemia, or sarcoid carcinomas

Common symptoms of AKF include:

• Anemia. The kidneys are responsible for producing erythropoietin (EPO), a hormone that stimulates red blood cell production. If kidney disease causes shrinking of the kidney, red blood cell production is reduced, leading to anemia.
• Bad breath or bad taste in mouth. Urea in the saliva may cause an ammonia-like taste in the mouth.
• Bone and joint problems. The kidneys produce vitamin D, which helps the body absorb calcium and keeps bones strong. For patients with kidney failure, bones may become brittle. In children, normal growth may be stunted. Joint pain may also occur as a result of high phosphate levels in the blood. Retention of uric acid may cause gout.
• Edema. Puffiness or swelling in the arms, hands, feet, and around the eyes.
• Frequent urination.
• Foamy or bloody urine. Protein in the urine may cause it to foam significantly. Blood in the urine may indicate bleeding from diseased or obstructed kidneys, bladder, or ureters.
• Cola-colored urine followed by oliguria (decreased urine output) or anuria (no urine output)
• Headaches. High blood pressure may trigger headaches.
• Hypertension, or high blood pressure. The retention of fluids and wastes causes blood volume to increase. This makes blood pressure rise.
• Increased fatigue. Toxic substances in the blood and the presence of anemia may cause the patient to feel exhausted.
• Itching. Phosphorus, normally eliminated in the urine, accumulates in the blood of patients with kidney failure. An increased phosphorus level may cause the skin to itch.
• Lower back pain. Patients suffering from certain kidney problems (like kidney stones and other obstructions) may have pain where the kidneys are located, in the small of the back below the ribs.
• Nausea. Urea in the gastric juices may cause upset stomach.