| Acute renal failure (ARF) is a sudden, severe decrease in the blood-filtering function of the kidneys, a serious condition that develops over the course of hours or over a few days. It can occur in individuals who previously had normal kidney function or in individuals with stabilized chronic kidney disease. The result of this sudden kidney failure is the accumulation of protein waste products in the body (urea and creatinine) that are normally filtered out of blood by the kidneys and excreted in the urine. There are three types of ARF: prerenal, intrinsic, and postrenal, each caused by different conditions.
Prerenal ARF is characterized by hemodynamic changes (related to blood or fluid volume) that decrease the flow of blood to the kidneys (renal perfusion); prerenal failure is caused by conditions that exist before the kidneys begin the filtering process. These conditions involve inadequate blood flow to the kidneys through acute blood loss, low blood pressure, congestive heart failure, anesthesia, uncontrolled diabetes, acute fluid loss and dehydration (e.g., from diuretics, vomiting, or diarrhea), heat prostration, burns, severe liver disease (e.g., cirrhosis, or sepsis).
Intrinsic ARF arises from conditions within the kidneys themselves that cause injury to the renal tubules that filter blood and produce urine. Injury may stem from the effects of chronic kidney failure or end stage renal disease (ESRD), or may be caused by inflammation of the capillaries or "glomeruli" (acute glomerulonephritis), drugs (e.g., prescription drugs such as non-steroidal anti-inflammatory drugs, sulfonamides, penicillins, and painkillers) or poisons (e.g., toxic chemicals and radiocontrast dyes used for x-rays), or overwhelming bacterial infection or severe allergic reactions.
Conditions that affect drainage of urine from the urinary tract after urine leaves the kidneys is known as postrenal ARF. Postrenal failure occurs as a result of acute obstruction anywhere in the urinary drainage system (urinary tract), which may be caused by kidney stones, bladder stones, scar tissue, surgical error, blood clots, cancer, or benign prostate enlargement.
Although there are many causes for acute renal failure, individuals with previously diagnosed chronic renal failure (CRF) are at greater risk than any individual with normal kidney function. Other risk factors include regular drug use (especially non-steroidal anti-inflammatory drugs [NSAIDs], antifungal agents, and diuretics), exposure to toxins, severe allergic reactions or systemic infection, recent surgery, trauma, or hospitalization.Incidence and Prevalence: Approximately 7.2% of all hospitalized individuals develop acute renal failure (Liano 811). About 0.9% of individuals are found to have acute renal failure upon hospital admission, approximately 51% of individuals with non-hospital-acquired acute renal failure were known to have chronic renal disease (Kaufman 191). |
Source: Medical Disability Advisor
| History: The symptoms reported may be non-specific. The individual may report thirst or dizziness in an upright position (orthostatic dizziness). A history of blood loss (excessive bleeding) or fluid loss (vomiting, diarrhea, diuresis) may be reported. There may be weight loss over a period of hours to a few days, reflecting fluid loss and dehydration. The individual may report nausea, vomiting, anorexia, lethargy, confusion, headache, or even a seizure. A metallic taste in the mouth may be reported. Shortness of breath, difficulty breathing on exertion, chest pain, or swelling in the feet and ankles may have been observed by the individual. The individual may have noted easy bruising or bleeding. Low or excessive urine production may be reported. There may be pain at the side of the back (flank pain), blood in the urine, or foamy urine. The individual may report drug use or exposure to toxins, or recent infection, allergic reaction, surgery, trauma, or hospitalization. Physical exam: In prerenal ARF, signs of dehydration may be evident. The skin may not return easily to its normal position when pulled up (decreased skin turgor). The veins in the neck may be "collapsed" due to dehydration. The mucous membranes of the mouth may be very dry. Evaluation of blood pressure (while lying, sitting, and standing) and heart rate may reveal orthostatic changes, again indicative of dehydration. In intrinsic or postrenal ARF, individuals may not appear dehydrated, and may, in fact, have evidence of congestive heart failure, with lower extremity edema, crackles heard on auscultation of the lung, and distended neck veins. Tests: A complete blood count (CBC) may reveal reduced red blood cells (RBCs) and loss of blood volume. Serum electrolytes may be abnormal, especially the ratio of sodium to potassium (electrolyte imbalance). Bicarbonate (HCO3), a measure of carbon dioxide (CO2) regulated by the kidneys, may be reduced. BUN (blood urea nitrogen) and creatinine will be measured in blood serum; these primary protein waste products in the blood are diagnostic for ARF and will typically be elevated. Blood serum may also be tested for the presence of abnormal antibodies that may indicate an underlying autoimmune or inflammatory process. Routine urinalysis may reveal an abnormal pH due to acidity, abnormal concentration of solids and water (specific gravity), the presence of protein or blood cells in the urine, or the presence of glucose or ketones in the urine. A 24-hour urine specimen will be collected to measure the amount of creatinine cleared by the kidneys. The volume of a 24-hour urine specimen may be abnormally high or low. Renal imaging may include ultrasound, computed tomography (CT), or magnetic resonance (MRI), which may reveal structural abnormalities in the urinary tract or abnormalities in kidney size. A renal scan with radiopaque contrast media (contrast agent) may also be performed to determine kidney shape and function. The glomerular filtration rate (GFR) may be measured to determine how well the kidneys are filtering waste, particularly creatinine. A fluid challenge test may be performed, in which 1 to 2 liters (1,000 to 2,000 cubic centimeters, or about 2 to 4 quarts) of fluid are infused into a vein while kidney function is monitored. If the diagnosis remains unclear, a renal biopsy may be performed to examine a stained sample of kidney tissue. |
Source: Medical Disability Advisor
| Initial treatment is directed at immediately restoring fluid balance, correcting electrolyte balance, and reducing the amount of excess waste products in the blood. To correct the fluid balance, either medication may be given to force the kidneys to excrete fluid (diuretics), or fluid volume may be given through an intravenous line to correct dehydration. Fluids may include isotonic saline or albumin. Transfusion with packed red blood cells may become necessary if the individual becomes severely anemic from fluid therapy. Medications may be given to help the heart pump blood more easily. Factors that may further injure the kidneys are avoided (e.g., drugs that have caused a toxic reaction will be discontinued and the use of radiopaque contrast media for x-ray imaging may be avoided because of possible damaging effects to susceptible individuals).
Treatment of an underlying cause may include antibiotics for infection or drug therapy to treat autoimmune or inflammatory conditions. Any obstruction of the flow of urine is corrected. Dietary changes are initiated to reduce the workload of the kidneys. A diet that is low in protein is usually introduced; waste products from protein are the primary toxins removed from the blood by the kidneys and excessive protein thereby increases the work of the kidneys. Dietary sodium may be limited because of its tendency to increase extracellular fluid.
If kidney function has decreased to the point of becoming life-threatening, treatment (hemodialysis) to decrease the amount of excess fluid and waste products is begun. |
Source: Medical Disability Advisor
| It may be difficult initially to determine the long-term prognosis. Acute renal failure is reversible if the underlying cause is corrected in a timely manner, making early diagnosis critical to successful recovery. Sometimes, however, depending on the cause of renal failure, permanent, irreversible kidney damage has already occurred. Most cases of acute renal failure due to dehydration resolve in 7 to 14 days. However, older individuals are at increased risk of developing permanent kidney damage as a result of acute renal failure due to dehydration.
The overall mortality rate for acute renal failure is about 45%, which increases to about 70% in cases that occur following surgical procedures (Liano 811). Mortality among individuals with non-hospital-acquired ARF is 15% (Kaufman 191). The most common causes of death associated with renal failure include sepsis, fluid and electrolyte imbalances, and progression of an underlying disease condition. Mortality decreases with postrenal obstructive ARF and increases with advanced age, severe underlying medical conditions, or with multisystem organ failure. |
Source: Medical Disability Advisor
| Many of the complications of acute renal failure are closely related to the underlying cause and its associated complications. Generalized infection (sepsis), lung infection, urinary tract infection, multiple organ failure, and cardiac failure may occur either before or after the onset of acute renal failure. Complications that are directly related to renal failure may include cardiac arrhythmias due to abnormal levels of potassium in the blood as well as respiratory problems (pulmonary edema) and congestive heart failure due to excess fluid volume. Acute renal failure may progress to chronic renal failure depending on the underlying cause and whether permanent irreversible damage to the kidneys has already occurred. |
Source: Medical Disability Advisor
| The underlying cause of the acute renal failure will influence any work restrictions or special accommodations. Many individuals experiencing acute renal failure will already be hospitalized for treatment of an underlying condition or for a surgical procedure; others will be admitted to the hospital for diagnosis and treatment when acute renal failure occurs or is suspected. Time off from work will be necessary until the kidney failure resolves, and then, more time may be needed for home recovery. Accommodations for a worker undergoing dialysis treatment may include additional leave from work and/or flex time to accommodate treatment days. Activity is allowed as the individual can tolerate. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- Has individual received adequate diagnostic testing to establish diagnosis of acute renal failure?
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Were other conditions with similar symptoms ruled out?
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Has cause of renal failure been identified?
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Has individual experienced any complications related to the renal failure, such as cardiac arrhythmias, pulmonary edema or congestive heart failure?
Regarding treatment:
- Did initial treatment effectively correct fluid balance and reduce the amount of excess electrolytes and waste products in the blood?
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Is underlying cause of the renal failure responding to treatment?
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Has individual complied with diet modification that includes low protein, sodium and potassium? Would individual benefit from a nutrition consult?
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If kidney function was decreased to the point of life-threatening, was hemodialysis begun? Will repeat hemodialysis be necessary?
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Did individual experience any complications related to the hemodialysis?
Regarding prognosis:
- Has permanent irreversible damage occurred to the kidneys?
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Is acute renal failure progressing towards chronic renal failure?
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Does individual have a coexisting condition, such as diabetes mellitus or hypertension that may complicate treatment or impact recovery?
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Source: Medical Disability Advisor
| Kaufman, J., et al. "Community Acquired Acute Renal Failure." American Journal of Kidney Diseases 17 (1991): 191-198.Liano, F., et al. "Epidemiology of Acute Renal Failure: A Prospective, Multicenter, Community-Based Study." Kidney International 50 3 (1996): 811-818. |
Source: Medical Disability Advisor
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