Types
Kidney disease is broadly classifies as:
Acute kidney disease or acute kidney failure (AKF): It occurs when the kidney function is reduced greatly or lost abruptly. 
Chronic kidney disease (CKD): It is an age related gradual loss of kidney function and is often symptomless in the initial stages. Because loss of kidney function is gradual in CKD, there are different stages of CKD.

• Mild CKD: It occurs when the kidneys are damaged and cause slight decrease in GFR i.e., between 60 and 89 mL/min/1.73m2 
• Moderate CKD occurs when the GFR decreases further and may lie anywhere between 30 and 59 mL/min/1.73m2.
• KIDNEY D
• In severe CKD, the filtration rate is reduced to 15-29 mL/min/1.73m2.
• Finally, when the GFR reduces below 15 mL/min/1.73m2, the stage of kidney failure is reached, where the patient needs dialysis for carrying out the filtration function.