<p>Chronic kidney disease is exactly what it sounds like-the gradual and permanent loss of kidney function over time. This usually takes a while, from months to years, and it can be divided into five stages of worsening severity. With stage 1, there is only slight kidney damage with normal or increased filtration-a glomerular filtration rate of more than 90 mL/min/1.73 square meters. It becomes a mild decrease in kidney function with 60 to 89 in stage 2 kidney disease, while stage 3 makes for a moderate decrease and a GFR between 30 and 59. Stage 4 chronic kidney disease means the patient has a filtration rate of 15 to 29, with a kidney severely malfunctioning. During the final stage, the patient needs dialysis or transplantation to stay alive since there is total or near-total loss of kidney function during end-stage renal disease. The other option is acute kidney failure, which happens over days or weeks at the most. This usually happens because of a condition which directly affects the kidney, its blood supply, or its urine flow, and it is usually reversible with complete recovery as long as the underlying disease is properly treated.</p>