Renal failure or kidney failure is a situation in which the kidneys fail to function adequately. It is divided in acute and chronic forms; either form may be due to a large number of other medical problems.
Biochemically, it is typically detected by an elevated serum creatinine. In the science of physiology, renal failure is described as a decrease in the glomerular filtration rate. When the kidneys malfunction, problems frequently encountered are abnormal fluid levels in the body, deranged acid levels, abnormal levels of potassium, 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.
Renal failure can broadly be divided into two categories: acute
renal failure. The type of renal failure is determined by the trend in the serum creatinine
. Other factors which may help differentiate acute and chronic kidney disease include the presence of anemia
and the kidney size on ultrasound
. Chronic kidney disease generally leads to anemia and small kidney size.
Acute renal failure
Acute renal failure
(ARF) is, as the name implies, a rapidly progressive loss of renal function
, generally characterized by oliguria
production, quantified as less than 400 mL
per day in adults, less than 0.5 mL/kg/h in children or less than 1 mL/kg/h in infants); body water
and body fluids disturbances; and electrolyte
derangement. An underlying cause must be identified to arrest the progress, and dialysis
may be necessary to bridge the time gap required for treating these fundamental causes. ARF can result from a large number of causes.
Chronic kidney disease
Stage 5 Chronic Kidney Disease
(CKD) can either develop slowly and show few initial symptoms, be the long term result of irreversible acute disease or be part of a disease progression. There are many causes of CKD. The most common cause is diabetes mellitus
. The second most common cause is long-standing, uncontrolled, hypertension. Polycystic kidney diease 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. Stage 1 CKD is mildly diminished renal function, with few overt symptoms. Stage 5 CKD
is a severe illness and requires some form of renal replacement therapy (dialysis
) or kidney transplant
Acute on chronic renal failure
Acute renal failure can be present on top of chronic renal failure. This is called acute-on-chronic renal failure (AoCRF). The acute part of AoCRF may be reversible and the aim of treatment, as with ARF, is to return the patient to their baseline renal function, which is typically measured by serum creatinine
. AoCRF, like ARF, can be difficult to distinguish from chronic renal failure, if the patient has not been monitored by a physician
and no baseline (i.e., past) blood work is available for comparison.
Use of the term uremia
Before the advancement of modern medicine, renal failure was often 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, that was thought to be caused by the urine mixing with the blood instead of being voided through the urethra. The term uremia
is now used to loosely describe the illness accompanying kidney failure.