('''ARF''') 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 .
Renal Failure , whether
Chronic or acute, is usually categorised according to ''pre-renal, renal'' and ''post-renal'' causes:
- ''Pre-renal'' (causes in the blood supply):
- --- Hypotension (decreased blood supply), usually from Shock or Dehydration and fluid loss, Heart Attack
- --- vascular problems, such as Atheroembolic Disease and Renal Vein Thrombosis (which in part may be secondary to loss of Coagulation Factor s due to renal dysfunction)
- ''Renal'' (damage to the kidney itself):
- --- Infection
- --- Toxin s or Medication (e.g. some NSAID s, Aminoglycoside antibiotics, Amphotericin B , Iodinated Contrast , 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, MDMA (ecstasy) 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 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'' (causes in the urinary tract):
- --- Urinary Retention (as a side-effect of Medication or due to Benign Prostatic Hypertrophy , Kidney Stones )
- --- Pyelonephritis
- --- obstruction due to abdominal malignancy (e.g. Ovarian Cancer , Colorectal Cancer ), or obstructed urinary catheter.
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 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 criteriaBellomo 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
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Criteria for ARF (Figure) .Lameire N, Van Biesen W, Vanholder R. ''Acute renal failure.''
Lancet 2005;365:417-30. PMID 15680458. 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.
Acute renal failure is usually reversible if treated promptly and appropriately. The main interventions are monitoring fluid intake and output as closely as possible; insertion of a or
Suprapubic Catheter ) may be necessary.
Metabolic Acidosis and
Hyperkalemia , two prime complications of renal failure, may require medical treatment with
Sodium Bicarbonate administration and antihyperkalemic measures, respectively.
Dopamine or other
Inotrope s may be given to improve
Cardiac Output and renal perfusion, and
Diuretic s (in particular
Furosemide ) may be administered. If a
Swan-Ganz Catheter is used, a ''pulmonary artery occlusion pressure'' (PAOP) of 18
MmHg (2.4 kPa) is the target for inotropic support.
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 and require lifelong
Dialysis or a
Kidney Transplant .
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.Bywaters EG, Beall D. ''Crush injuries with impairment of renal function''.
Br Med J 1941;1:427-32. Reprinted in J Am Soc Nephrol 1998;9:322-32. PMID 9527411. During the Korean and Vietnam wars, the incidence of ARF decreased due to better acute management and intravenous infusion of fluids.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.
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