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Renal failure

Renal failure or kidney failure (formerly called renal insufficiency or chronicrenal insufficiency) is a situation in which the kidneys fail to function adequately. There are two forms: acute (acute kidney injury) and chronic (chronic kidney disease); either form may be due to a large number of other medical problems.

Biochemically, it is typically detected by an elevated serum creatinine. In thescience of physiology, renal failure is described as a decrease in the glomerular filtration rate. When the kidneys malfunction, problems frequently encounteredare abnormal fluid levels in the body, deranged acid levels, abnormal levels ofpotassium, calcium, phosphate, hematuria (blood in the urine) and (in the longer term) anemia. Long-term kidney problems have significant repercussions on other diseases, such as cardiovascular disease.

ClassificationRenal failure can broadly be divided into two categories: acute kidney injury orchronic kidney disease. The type of renal failure is determined by the trend inthe serum creatinine. Other factors which may help differentiate acute and chro

nic kidney disease include the presence of anemia and the kidney size on ultrasound. Chronic kidney disease generally leads to anemia and small kidney size

[edit] Acute kidney injuryMain article: Acute kidney injuryAcute kidney injury (AKI), previously called acute renal failure (ARF), is a rapidly progressive loss of renal function, generally characterized by oliguria (decreased urine production, quantified as less than 400 mL per day in adults,[1] less than 0.5 mL/kg/h in children or less than 1 mL/kg/h in infants); body waterand body fluids disturbances; and electrolyte derangement. AKI can result from avariety of causes, generally classified as prerenal, intrinsic, and postrenal.An underlying cause must be identified and treated to arrest the progress, and d

ialysis may be necessary to bridge the time gap required for treating these fundamental causes.

[edit] Chronic kidney diseaseMain article: Chronic kidney diseaseChronic kidney disease (CKD) can develop slowly and show few initial symptoms, be the long term result of irreversible acute disease, or be part of a disease progression.

[edit] Acute-on-chronic renal failureAcute kidney injury can be present on top of chronic kidney disease. This is called acute-on-chronic renal failure (AoCRF). The acute part of AoCRF may be rever

sible and the aim of treatment, as with AKI, is to return the patient to their baseline renal function, which is typically measured by serum creatinine. AoCRF,like AKI, can be difficult to distinguish from chronic kidney disease, if the patient has not been monitored by a physician and no baseline (i.e., past) blood work is available for comparison.

[edit] SymptomsSymptoms of kidney disease can vary from person to person. Some people with kidney disease may not even feel sick, or they may not notice their symptoms. If thekidney function fails, the waste products accumulate in the blood and the body,termed azotemia. Very mild levels of azotaemia may produce little or no symptoms, but if the kidney failure continues then symptoms will become noticeable (ifthe failure is of sufficient degree to cause symptoms). Renal failure accompanie

d with noticeable symptoms is termed uraemia.[2]

Symptoms of kidney failure include:[2][3][4][5]

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High levels of urea in the blood, which can result in:Vomiting and/or diarrhea, which may lead to dehydrationNauseaWeight lossNocturnal urinationFoamy or bubbly urine

More frequent urination, or in greater amounts than usual, with pale urineLess frequent urination, or in smaller amounts than usual, with dark coloured urineBlood in the urinePressure, or difficulty urinatingA build up of phosphates in the blood that diseased kidneys cannot filter out may cause:ItchingBone damageMuscle cramps (caused by low levels of calcium which can cause hypocalcaemia)A build up of potassium in the blood that diseased kidneys cannot filter out (called hyperkalemia) may cause:

Abnormal heart rhythmsMuscle paralysis[6]Failure of kidneys to remove excess fluid may cause:Swelling of the legs, ankles, feet, face and/or handsShortness of breath due to extra fluid on the lungs (may also be caused by anemia)Polycystic kidney disease, which causes large, fluid-filled cysts on the kidneysand sometimes the liver, can cause:Pain in the back or sideHealthy kidneys produce the hormone erythropoietin which stimulates the bone marrow to make oxygen-carrying red blood cells. As the kidneys fail they produce less erythropoietin resulting in fewer red blood cells being produced to replace the natural breakdown of old red blood cells. As a result the blood carries less

haemoglobin, which is known as anemia. This can result in:Feeling tired and/or weakMemory problemsDifficulty concentratingDizzinessLow blood pressureOther symptoms include:Appetite loss, a bad taste in the mouthDifficulty sleepingDarkening of the skin[edit] Causes[edit] Causes of acute renal failureAcute kidney failure usually occurs as the result of a sudden interruption in the blood supply to the kidney, or as a result of a toxic overload of the kidneys.Some causes of acute failure include accidents, injuries or complications fromsurgery where the kidneys are deprived of normal blood flow for an extended period of time. Heart-bypass surgery is an example of a situation in which the kidneys receive reduced blood flow.

Drug overdoses, whether accidental or from chemical overloads of drugs such as antibiotics or chemotherapy, may also cause the onset of acute kidney failure. Unlike in chronic kidney disease, however, the kidneys can often recover from acute failure, allowing the patient to resume a normal life. People suffering from acute failure require supportive treatment until their kidneys recover function,and they often remain at an increased risk of developing future kidney failure.[

7]

[edit] Causes of chronic kidney disease

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There are many causes of CKD. The most common cause is diabetes mellitus. The second most common cause is long-standing, uncontrolled, hypertension. Polycystickidney disease is also a well known cause of chronic kidney disease. The majority of people afflicted with polycystic kidney disease have a family history of the disease. Many other genetic illnesses also affect kidney function. Overuse ofsome common drugs, such as aspirin, ibuprofen, cocaine and acetaminophen can also cause chronic kidney damage.[8]

Investigation[edit] Methods of Measurement for CKDStages of kidney failureChronic kidney failure is measured in five stages, which are calculated using apatients GFR, or glomerular filtration rate. Stage 1 CKD is mildly diminished renal function, with few overt symptoms. Stages 2 and 3 need increasing levels of supportive care from their medical providers to slow and treat their renal dysfunction. Patients in stages 4 and 5 usually require preparation of the patient towards active treatment in order to survive.Stage 5 CKD is considered a severe illness and requires some form of renal replacement therapy (dialysis) or kidney tr

ansplant whenever feasible.

Glomerular filtration rateA normal GFR varies according to many factors, including sex, age, body size andethnicity. Renal professionals consider the glomerular filtration rate (GFR) tobe the best overall index of kidney function. [9]The National Kidney Foundationoffers an easy to use on-line GFR calculator.[10] for anyone who is interestedin knowing their glomerular filtration rate.(A serum creatinine level, a simpleblood test, is needed to use the calculator).

[edit] Use of the term uremiaBefore the advancement of modern medicine, renal failure was often referred to as uremic poisoning. Uremia was the term used to describe the contamination of th

e blood with urine. Starting around 1847, this term was used to describe reducedurine output, that was thought to be caused by the urine mixing with the bloodinstead of being voided through the urethra.[citation needed] The term uremia isnow used to loosely describe the illness accompanying kidney failure.[11]

http://en.wikipedia.org/wiki/Renal_failure (retrieved MArch 6, 2010. 8:35pm)