Dialysis is done when the amount of excretory substances in the patient’s body increases excessively and becomes very ill (uremia). Kidney health is assessed by testing creatinine clearance in urine. The amount of creatinine cleared from the blood per minute is called creatinine clearance. Creatinine clearance in a healthy person is 125 cc/min. Dialysis is done when renal creatinine clearance is 10-12 cc/min.