2021 Aug 13. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–.
The term renal failure denotes the inability of the kidneys to perform excretory function leading to retention of nitrogenous waste products from the blood. Functions of the kidney are as follows:
Electrolyte and volume regulation
Excretion of nitrogenous waste
Elimination of exogenous molecules, for example, many drugs
Synthesis of a variety of hormones, for example, erythropoietin
Metabolism of low molecular weight proteins, for example, insulin
Acute and chronic renal failure are the two kinds of kidney failure.
Acute Renal Failure (ARF)
ARF is the syndrome in which glomerular filtration declines abruptly (hours to days) and is usually reversible. According to the KDIGO criteria in 2012, AKI can be diagnosed with any one of the following: (1) creatinine increase of 0.3 mg/dL in 48 hours, (2) creatinine increase to 1.5 times baseline within last 7 days, or (3) urine volume less than 0.5 mL/kg per hour for 6 hours. Recently the term acute kidney injury (AKI) has replaced ARF because AKI denotes the entire clinical spectrum from a mild increase in serum creatinine to overt renal failure.
Chronic Renal Failure (CRF)
CRF or chronic kidney disease (CKD) is defined as a persistent impairment of kidney function, in other words, abnormally elevated serum creatinine for more than 3 months or calculated glomerular filtration rate (GFR) less than 60 ml per minute / 1.73m2. It often involves a progressive loss of kidney function necessitating renal replacement therapy (dialysis or transplantation). When a patient needs renal replacement therapy, the condition is called end-stage renal disease (ESRD).
CKD classified based on grade:
Grade 1: GFR greater than 90
Grade 2: 60 to 89
Grade 3a: 45 to 59
Grade 3b: 30 to 44
Grade 4: 15 to 29
Grade 5: Less than 15
CKD classified based on stage:
Stage 1: GFR greater than 90
Stage 2: 60 to 89
Stage 3: 30 to 59
Stage 4: 15 to 29
Stage 5: Less than 15