Dialysis

In medicine, renal dialysis is a method for removing waste such as urea from the blood when the kidneys are incapable of this (i.e. in renal failure).

In acute renal failure, (renal) dialysis is generally initiated when the renal function has deteriorated to an extent that it is threatening the body's physiology. Volume overload (i.e. hypervolemia) that is unresponsive to strong diuretics, such as furosemide, and severe hyperkalemia are two common indications for dialysis.

In chronic renal failure the problem is usually longstanding, and the decision is based on the possibility of a renal transplant, complications of the malfunctioning kidney (e.g. hyperkalemia, uremia) and personal factors (such as tiredness due to the uremia). Chronic renal failure that does not have an acute (i.e. reversible) component and requires dialysis is called end-stage renal disease (ESRD). There is no general agreement among nephrologists on when to start dialysis. In Canada some nephrologists advocate that patients with CRF should start dialysis when the GFR is below 15 mL/min and below 20 mL/min for patients with diabetes mellitus. Canadian guidelines suggest considering dialysis when the GFR is less than 12 mL/min In the United States, dialyisis is initated at a GFR of 15 mL/min in diabetics and 10mL/min in non-diabetics, in conjuction with uremic sypmtoms. Most guidelines agree that dialysis should be started before the GFR drops below 6 mL/min. The rationale for starting dialysis early is it prevents illness associated with severe uremia and may minimize long-term complications associated with kidney failure. Studies have shown that starting dialysis with a lower GFR is associated with a poor nutritional status which is associated with a higher mortality in the first two years of treatment.

Acute renal failure can present on top of (i.e. in addition to) chronic renal failure. This is called acute-on-chronic renal failure (AoCRF) and may require dialysis temporarily (until the acute component of the renal failure resolves).