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Renal failure

Renal failure is when the kidneys fail to function properly. It can broadly be divided into two categories - acute renal failure and chronic renal failure.

Table of contents
1 Acute renal failure
2 Chronic renal failure
3 Diagnosis
4 Causes
5 Treatment

Acute renal failure

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Chronic renal failure

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There are many causes of renal failure and a good method of organizing them is to divide them into the pre-renal, renal and post-renal causes of renal failure.

The most common prerenal cause of acute renal failure is hypotension or decreased blood flow, usually from shock or dehydration/fluid loss. Other causes include vascular problems such as renal artery stenosis and thrombus.

Damage to the kidney parenchyma itself can cause renal failure. This would include such things as infection, toxins and autoimmune diseases.

Postrenal problems affecting the flow of urine beyond the kidneys can result in a postrenal cause of renal failure. Thus, any disease affecting the ureters, bladder or urethra can lead to this.


Acute renal failure is usually reversible if treated promptly and appropriately. Dialysis may be required temporarily. The kidneys will recover with resumption of adequate renal perfusion with fluid resuscitation. The underlying cause should also be investigated and treated.

Chronic renal failure, on the other hand, is not reversible. If the renal function deteriorates enough, the patient may well end up requiring dialysis or a kidney transplant on a long term basis.