Kidney Disease

Chronic kidney disease
Chronic kidney disease occurs when one suffers from gradual and usually permanent loss of kidney function over time. This happens gradually, usually months to years. Chronic kidney disease is divided into five stages of increasing severity (see Table 1 below). The term "renal" refers to the kidney, so another name for kidney failure is "renal failure." Mild kidney disease is often called renal insufficiency.
With loss of kidney function, there is an accumulation of water; waste; and toxic substances, in the body, that are normally excreted by the kidney. Loss of kidney function also causes other problems such as anemia, high blood pressure, acidosis (excessive acidity of body fluids), disorders of cholesterol and fatty acids, and bone disease.
Stage 5 chronic kidney disease is also referred to as kidney failure, end-stage kidney disease, or end-stage renal disease, wherein there is total or near-total loss of kidney function. There is dangerous accumulation of water, waste, and toxic substances, and most individuals in this stage of kidney disease need dialysis or transplantation to stay alive.
Unlike chronic kidney disease, acute kidney failure develops rapidly, over days or weeks.

• Acute kidney failure usually develops in response to a disorder that directly affects the kidney, its blood supply, or urine flow from it.
  
  
• Acute kidney failure is often reversible, with complete recovery of kidney function.
  
  
  
  
• Some patients are left with residual damage and can have a progressive decline in kidney function in the future.
  
  
• Others may develop irreversible kidney failure after an acute injury and remain dialysis-dependent.

Table 1. Stages of Chronic Kidney Disease

Stage	Description	GFR* mL/min/1.73m2
1	Slight kidney damage with normal or increased filtration	More than 90
2	Mild decrease in kidney function	60-89
3	Moderate decrease in kidney function	30-59
4	Severe decrease in kidney function	15-29
5	Kidney failure	Less than 15 (or dialysis)

*GFR is glomerular filtration rate, a measure of the kidney's function.