Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Renal Failure, Acute


Related Terms

  • Acute Kidney Injury
  • ARF
  • Postrenal Azotemia
  • Prerenal Azotemia
  • Renal Failure
  • Renal Insufficiency

Differential Diagnosis

  • Chronic renal failure

Specialists

  • Internal Medicine Physician
  • Nephrologist
  • Urologist

Comorbid Conditions

Factors Influencing Duration

Most major improvements occur within the first few weeks of the recovery phase. It may take several months for the individual to fully return to normal activities. The underlying cause of acute renal failure, the degree of kidney dysfunction, the required treatment (such as dialysis), and response to treatment, may affect the recovery period. In some cases, chronic renal failure may develop and affect the length of disability.

Medical Codes

ICD-9-CM:
584.5 - Acute kidney failure with lesion of tubular necrosis
584.6 - Acute kidney failure with lesion of renal cortical necrosis
584.7 - Acute kidney failure with lesion of renal medullary [papillary] necrosis
584.8 - Acute kidney failure with other specified pathological lesion in kidney
584.9 - Renal Failure, Acute, Unspecified; Acute Kidney Injury (Nontraumatic)

Overview

Acute renal failure (ARF), increasingly called acute kidney injury (AKI), 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 (acute-on-chronic renal failure). The results of this sudden kidney failure are pH changes, fluid overload, electrolyte imbalance, and 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 hypoperfusion); 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 (hemorrhage), low blood pressure (hypotension), congestive heart failure, anesthesia, uncontrolled diabetes, acute fluid loss (dehydration) (e.g., from diuretics, vomiting, or diarrhea), heat prostration, burns, or 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, semi-synthetic penicillins, and painkillers) or poisons (e.g., toxic chemicals and radiocontrast dyes used for x-rays), overwhelming bacterial infection, or severe allergic reactions.

Conditions that affect drainage of urine from the urinary tract after urine leaves the kidneys constitute 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 3% to 7% of all hospitalized individuals develop acute renal failure (Brenner). 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



Diagnosis

History: The symptoms reported may be non-specific. The individual may report fatigue, 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 (dehydration). The individual may report nausea, vomiting, loss of appetite (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 (peripheral edema) 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 and distended neck veins. Crackles may be heard on auscultation of the lung (due to pulmonary edema).

Tests: Blood urea nitrogen (BUN ) 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. Serum electrolytes may be abnormal, especially the ratio of sodium to potassium (electrolyte imbalance). A complete blood count (CBC) may reveal reduced red blood cells (RBCs) and loss of blood volume. Bicarbonate (HCO3), a measure of carbon dioxide (CO2) regulated by the kidneys, may be reduced. Blood serum may also be tested for the presence of abnormal antibodies titers 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 (proteinuria) or red blood cells (hematuria) in the urine, or the presence of glucose (glycosuria) or ketones (ketonuria) 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



Treatment

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. 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 in the diet 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 to decrease the amount of excess fluid and waste products (hemodialysis or peritoneal dialysis) is begun.

Source: Medical Disability Advisor



Prognosis

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.

In-hospital mortality associated with acute renal failure from acute tubular necrosis and nephrotoxins ranges from 24% to 62% (Waikar). 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



Complications

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 metabolic acidosis, cardiac arrhythmias due to abnormal levels of potassium in the blood (hyperkalemia) as well as respiratory problems (pulmonary edema) and congestive heart failure resulting from 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



Ability to Work (Return to Work Considerations)

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.

Risk: Jobs that entail exposure to known toxins should be avoided. For more information, refer to "Disease and Injury Causation," pages 350-351.

Capacity: Blood testing should verify no obvious limit in returning to work.

Tolerance: Fatigue is a prominent symptom in renal failure and may limit work return, though this tends to improve with time.

Source: Medical Disability Advisor



Maximum Medical Improvement

As this may be a reversible disease, one should wait for MMI until creatinine is stable for 30 days.

Source: Medical Disability Advisor



Failure to Recover

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?
  • Were other conditions with similar symptoms ruled out?
  • Has cause of renal failure been identified?
  • 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?
  • Is underlying cause of the renal failure responding to treatment?
  • Has individual complied with diet modification that includes low protein, sodium and potassium? Would individual benefit from a nutrition consult?
  • If kidney function was decreased to the point of life-threatening, was hemodialysis or peritoneal dialysis begun? Will repeated dialysis be necessary?
  • Did individual experience any complications related to the hemodialysis or peritoneal dialysis?

Regarding prognosis:

  • Has permanent irreversible damage occurred to the kidneys?
  • Is acute renal failure progressing towards chronic renal failure?
  • Does individual have a coexisting condition, such as diabetes mellitus or hypertension that may complicate treatment or impact recovery?

Source: Medical Disability Advisor



References

Cited

Brenner & Rector's The Kidney. 8th ed. W.B. Saunders, 2007.

Kaufman, J., et al. "Community Acquired Acute Renal Failure." American Journal of Kidney Diseases 17 (1991): 191-198.

Melhorn, J. Mark, and William Ackerman, eds. Disease and Injury Causation, Guides to the Evaluation of. AMA Press, 2008.

Waikar, Sushrut S. , Kathleen D. Liu, and Glenn M. Chertow. "Diagnosis, Epidemiology and Outcomes of Acute Kidney Injury." Clinical Journal of the American Society and Nephrology 3 3 (2008): 844-861.

Source: Medical Disability Advisor






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