Acute renal failure overview

Jump to: navigation, search

Acute renal failure Microchapters

Home

Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Acute renal failure from other Diseases

Epidemiology and Demographics

Risk Factors

Natural History, Complications and Prognosis

Diagnosis

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

CT

MRI

Ultrasound

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

Case #1

Acute renal failure overview On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Acute renal failure overview

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Acute renal failure overview

CDC on Acute renal failure overview

Acute renal failure overview in the news

Blogs on Acute renal failure overview

Directions to Hospitals Treating Acute renal failure

Risk calculators and risk factors for Acute renal failure overview

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Acute renal failure (ARF), also known as acute kidney failure, is a rapid loss of renal function due to damage to the kidneys, resulting in retention of nitrogenous (urea and creatinine) and non-nitrogenous waste products that are normally excreted by the kidney. Depending on the severity and duration of the renal dysfunction, this accumulation is accompanied by metabolic disturbances, such as metabolic acidosis (acidification of the blood) and hyperkalaemia (elevated potassium levels), changes in body fluid balance, and effects on many other organ systems. It can be characterized by oliguria or anuria (decrease or cessation of urine production), although nonoliguric ARF may occur. It is a serious disease and treated as a medical emergency.

Historical Perspective

Before the advancement of modern medicine, acute renal failure might be referred to as uremic poisoning. Uremia was the term used to describe the contamination of the blood with urine. Starting around 1847 this term was used to describe reduced urine output, now known as oliguria, which was thought to be caused by the urine's mixing with the blood instead of being voided through the urethra. Acute renal failure due to acute tubular necrosis (ATN) was recognised in the 1940s in the United Kingdom, where crush victims during the Battle of Britain developed patchy necrosis of renal tubules, leading to a sudden decrease in renal function.[1] During the Korean and Vietnam wars, the incidence of ARF decreased due to better acute management and intravenous infusion of fluids.[2]

Classification

Acute renal failure can complicate a wide spectrum of disorders, and for the purpose of diagnosis and management is divided according to the mechanism that lead to renal compromise. The three categories are pre-renal azotemia (diseases that cause renal hypoperfusion), renal azotemia (diseases directly affecting the renal parenchyma), and post-renal azotemia (diseases affecting the urinary tract causing obstruction). However, the first consensus definition described and the most used definition is known as the RIFLE criteria. The acronym combines a classification of 3 levels of renal dysfunction (Risk, Injury, Failure) with 2 clinical outcomes (Loss, ESRD) to give the RIFLE stages of AKI.

Causes

Glomerular filtration rate depends on multiple factors, particularly the renal blood flow. The pressure difference across the renal vasculature i.e the difference in pressure between the renal arterioles and venules is directly proportional to the GFR. Any decrease in renal blood flow, injury to the renal tubules or obstruction to the urinary tract outflow can cause decreased urinary output.

Differentiating Acute renal failure from other Diseases

Various parameters like fractional sodium excretion, urinary sodium concentration, urine osmolality and U/P creatinine ratio have been used to diagnose acute renal failure. The fractional sodium excretion is identifies as the most effective non-invasive test in formulating the differential diagnosis of acute renal failure [3].

Epidemiology and Demographics

Acute kidney injury is common among hospitalized patients. It affects some 3-7% of patients admitted to the hospital and approximately 25-30% of patients in the intensive care unit [4].

Risk Factors

Acute renal failure always occurs in connection with some other medical condition or event. Being hospitalized with a serious condition requiring intensive care is the biggest risk factor. The risk factors for acute renal failure is divided into three major categories, namely pre-renal factors, renal factors and post-renal factors.

Diagnosis

History and Symptoms

When a patient presents with uremic symptoms, first step is to differentiate an acute from a chronic process. A recent rise in serum creatinine levels indicate an acute pathology of renal failure, whereas chronically elevated creatinine levels are seen in chronic renal failure. However, chronic renal insufficiency is also associated with osteopathy, neuropathy and small, scarred kidneys.

Laboratory Findings

Renal failure is generally diagnosed either when creatinine or blood urea nitrogen tests are markedly elevated in an ill patient, especially when oliguria is present. Previous measurements of renal function may offer comparison, which is especially important if a patient is known to have chronic renal failure as well. If the cause is not apparent, a large amount of blood tests and examination of a urine specimen is typically performed to elucidate the cause of acute renal failure.

Ultrasound

Medical ultrasonography of the renal tract is essential to rule out obstruction of the urinary tract.

Other Diagnostic Studies

Kidney biopsy may be performed in the setting of acute renal failure, to provide a definitive diagnosis and sometimes an idea of the prognosis, unless the cause is clear and appropriate screening investigations are reassuringly negative.

Treatment

Surgery

If the cause of the acute renal failure is obstruction of the urinary tract, relief of the obstruction (with a nephrostomy or urinary catheter) may be necessary. Lack of improvement with fluid resuscitation, therapy-resistant hyperkalemia, metabolic acidosis, or fluid overload may necessitate artificial support in the form of dialysis or hemofiltration. Depending on the cause, a proportion of patients will never regain full renal function, thus having end stage renal failure requiring lifelong dialysis or a kidney transplant.

References

  1. Bywaters EG, Beall D (1941). "Crush injuries with impairment of renal function.". Br Med J (1): 427–32. PMID 9527411. 
  2. Schrier RW, Wang W, Poole B, Mitra A (2004). "Acute renal failure: definitions, diagnosis, pathogenesis, and therapy". J. Clin. Invest. 114 (1): 5–14. PMC 437979Freely accessible. PMID 15232604. doi:10.1172/JCI22353. 
  3. Espinel CH, Gregory AW (1980). "Differential diagnosis of acute renal failure". Clinical Nephrology. 13 (2): 73–7. PMID 7363517. 
  4. Brenner and Rector's The Kidney. Philadelphia: Saunders. 2007. ISBN 1-4160-3110-3. 

Linked-in.jpg