Chronic kidney disease (CKD) is a condition in which the kidneys are damaged and cannot filter blood as well as they should. CKD has varying levels of seriousness that can range from leakage of extra protein into the urine to kidney failure requiring dialysis, in which a machine filters the blood like healthy kidneys would, or a kidney transplant, where a kidney is donated from another person. If left untreated, CKD can progress to kidney failure (also known as end-stage renal disease) and early cardiovascular death.