The kidneys filter out wastes and water from the blood. Chronic kidney disease causes kidney function to slowly worsen over time until the patient needs dialysis to survive. Dialysis filters the blood through artificial means. The care of patients with chronic kidney disease involves managing diet, blood pressure, and medications to delay the need for dialysis as long as possible, and then making an organized transition to dialysis. Some evidence suggests that the earlier patients with kidney disease receive care from a nephrologist (a doctor who specializes in kidney disease), the better they do. Unfortunately, patients often do not see a nephrologist until kidney disease is in its late stages.