Acute renal failure
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225210464
2008-07-12T14:01:10Z
ToNToNi
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[[ca:Insuficiència renal aguda]]
{{Infobox_Disease |
Name = Acute renal failure |
Image = |
Caption = |
DiseasesDB = 11263 |
ICD10 = {{ICD10|N|17||n|17}} |
ICD9 = {{ICD9|584}} |
ICDO = |
OMIM = |
MedlinePlus = 000501 |
eMedicineSubj = med |
eMedicineTopic = 1595 |
MeshID = D007675 |
}}
'''Acute renal failure''' ('''ARF'''), also known as '''acute kidney failure''' or '''acute kidney injury''', is a rapid loss of [[renal function]] due to damage to the [[kidney]]s, 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 characterised 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]].
[[Image:Kidney – acute cortical necrosis.jpg|thumb|Kidney showing marked pallor of the cortex, contrasting to the darker areas of surviving medullary tissue. The patient died with acute renal failure]]
==Causes==
Acute renal failure is usually categorised (as in the [[flowchart]] below) according to ''pre-renal, renal'' and ''post-renal'' causes.
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{{familytree | | | | B01 | | | B02 | | | B03|B01=Pre-renal|B02=Renal|B03=Post-renal }}
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* ''Pre-renal'' (causes in the blood supply):
** [[hypovolemia]] (decreased blood volume), usually from [[Shock (medical)|shock]] or [[dehydration]] and fluid loss or excessive [[diuretic]]s use.
** [[hepatorenal syndrome]] in which renal [[perfusion]] is compromised in [[liver failure]]
** vascular problems, such as [[cholesterol embolism|atheroembolic disease]] and [[renal vein thrombosis]] (which can occur as a complication of the [[nephrotic syndrome]])
** [[infection]] usually [[sepsis]], systemic inflammation due to infection
* ''Renal'' (damage to the kidney itself):
** [[toxin]]s or [[medication]] (e.g. some [[NSAID]]s, [[aminoglycoside]] antibiotics, [[iodinated contrast]], [[Lithium salt|lithium]])
** [[rhabdomyolysis]] (breakdown of muscle tissue) - the resultant release of [[myoglobin]] in the blood affects the kidney; it can be caused by [[injury]] (especially crush injury and extensive blunt trauma), [[statin]]s, [[stimulant]]s and some other drugs
** [[hemolysis]] (breakdown of [[red blood cell]]s) - the [[hemoglobin]] damages the tubules; it may be caused by various conditions such as [[sickle-cell disease]], and [[lupus erythematosus]]
** [[multiple myeloma]], either due to [[hypercalcemia]] or "cast nephropathy" (multiple myeloma can also cause [[chronic renal failure]] by a different mechanism)
** acute [[glomerulonephritis]] which may be due to a variety of causes, such as anti glomerular basement membrane disease/[[Goodpasture's syndrome]], [[Wegener's granulomatosis]] or acute lupus nephritis with [[systemic lupus erythematosus]]
* ''Post-renal'' (obstructive causes in the urinary tract) due to:
** [[medication]] interfering with normal bladder emptying.
** [[benign prostatic hypertrophy]] or [[prostate cancer]].
** [[kidney stones]].
** due to abdominal malignancy (e.g. [[ovarian cancer]], [[colorectal cancer]]).
** obstructed [[urinary catheter]].
==Diagnosis==
In general, renal failure is diagnosed when either [[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 test]]s and examination of a [[urine]] specimen is typically performed to elucidate the cause of acute renal failure, [[medical ultrasonography]] of the renal tract is essential to rule out obstruction of the urinary tract.
Consensus criteria<ref>Bellomo R, Ronco C, Kellum JA, Mehta RL, Palevsky P; Acute Dialysis Quality Initiative workgroup. Acute renal failure - definition, outcome measures, animal models, fluid therapy and information technology needs: the Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group. Crit Care. 2004 Aug;8(4):R204-12. Epub 2004 May 24. PMID 15312219 [http://ccforum.com/content/8/4/R204 Full Text]. [http://ccforum.com/content/8/4/r204/figure/F1 Criteria for ARF (Figure)].</ref><ref>Lameire N, Van Biesen W, Vanholder R. ''Acute renal failure.'' [[The Lancet|Lancet]] 2005;365:417-30. PMID 15680458.</ref> for the diagnosis of ARF are:
* Risk: serum creatinine increased 1.5 times OR urine production of <0.5 ml/kg body weight for 6 hours
* Injury: creatinine 2.0 times OR urine production <0.5 ml/kg for 12 h
* Failure: creatinine 3.0 times OR creatinine >355 μmol/l (with a rise of >44) or urine output below 0.3 ml/kg for 24 h
* Loss: persistent ARF or more than four weeks complete loss of kidney function
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==
Acute renal failure may be reversible if treated promptly and appropriately. Resuscitation to normotension and a normal [[cardiac output]] is key. The main interventions are monitoring fluid intake and output as closely as possible; insertion of a [[Urinary catheterization|urinary catheter]] is useful for monitoring urine output as well as relieving possible bladder outlet obstruction, such as with an enlarged prostate. In the absence of fluid overload, administering [[intravenous fluid]]s is typically the first step to improve renal function. Fluid administration may be monitored with the use of a [[central venous catheter]] to avoid over- or under-replacement of fluid. If the cause is obstruction of the urinary tract, relief of the obstruction (with a [[nephrostomy]] or [[urinary catheter]]) may be necessary. [[Metabolic acidosis]] and [[hyperkalemia]], the two most serious biochemical manifestations of acute renal failure, may require medical treatment with [[sodium bicarbonate]] administration and antihyperkalemic measures, unless [[dialysis]] is required.
Should hypotension prove a persistent problem in the fluid replete patient, [[inotrope]]s such as [[norepinephrine]] and/or [[dobutamine]] may be given to improve [[cardiac output]] and hence renal perfusion. While a useful pressor, there is no evidence to suggest that [[dopamine]] is of any specific benefit,<ref>{{cite journal |author=Holmes CL, Walley KR |title=Bad medicine: low-dose dopamine in the ICU |journal=Chest |volume=123 |issue=4 |pages=1266–75 |year=2003 |pmid=12684320|doi=10.1378/chest.123.4.1266}}</ref> and at least a suggestion of possible harm. A [[Swan-Ganz catheter]] may be used, to measure ''pulmonary artery occlusion pressure'' to provide a guide to left atrial pressure (and thus left heart function) as a target for inotropic support.
The use of [[diuretics]] such as [[furosemide]], while widespread and sometimes convenient in ameliorating fluid overload, does not reduce the risk of complications and death.<ref>{{cite journal |author=Uchino S, Doig GS, Bellomo R, ''et al'' |title=Diuretics and mortality in acute renal failure |journal=Crit. Care Med. |volume=32 |issue=8 |pages=1669–77 |year=2004 |pmid=15286542|doi=10.1097/01.CCM.0000132892.51063.2F}}</ref> In practice, diuretics may simply mask things, making it more difficult to judge the adequacy of resuscitation.
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]].
==History==
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.<ref>Bywaters EG, Beall D. ''Crush injuries with impairment of renal function''. [[British Medical Journal|Br Med J]] 1941;1:427-32. Reprinted in J Am Soc Nephrol 1998;9:322-32. PMID 9527411.</ref> During the Korean and Vietnam wars, the incidence of ARF decreased due to better acute management and intravenous infusion of fluids.<ref>Schrier RW, Wang W, Polle B, Mitra A. ''Acute renal failure: definitions, diagnosis, pathogenesis, and therapy.'' J Clin Invest 2004;114:5-14. PMID 15232604. [http://www.jci.org/cgi/content/full/114/1/5 Full text].</ref>
==See also==
*[[Chronic kidney disease]]
*[[Dialysis]]
*[[Hepatorenal syndrome]]
*[[Renal failure]]
==References==
{{Sisterlinks}}
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{{Nephrology}}
[[Category:Medical emergencies]]
[[Category:Kidney diseases]]
[[Category:Organ failure]]
[[Category:Causes of death]]
[[ar:فشل كلوي حاد]]
[[az:Kəskin böyrək çatışmamazlığı]]
[[ca:Insuficiència renal aguda]]
[[de:Akutes Nierenversagen]]
[[es:Insuficiencia renal aguda]]
[[fr:Insuffisance rénale aiguë]]
[[ja:急性腎不全]]
[[pt:Insuficiência renal aguda]]
[[zh:急性肾衰竭]]