In hemodialysis, a dialysis machine and a special filter called an artificial kidney, or a dialyzer, are used to clean your blood. To get your blood into the dialyzer, the doctor needs to make an access, or entrance, into your blood vessels. This is done with minor surgery, usually to your arm. Hemodialysis treatments usually last about four hours, and they are done three times a week. Your dialysis care team will monitor your treatment with monthly lab tests to ensure you are getting the right amount of dialysis. One of the measures your dialysis care team may use is called urea reduction ratio (URR). Another measure is called Kt/V. Kt/V is a number used to quantify hemodialysis (waste removal) and peritoneal dialysis treatment adequacy. 
- K - dialyzer clearance of urea
- t - dialysis time
- V - volume of distribution of urea, approximately equal to patient's total body water
To ensure that you are getting enough dialysis:
- your Kt/V should be at least 1.2 or
- your URR should be at least 65 percent.
In medicine, hemodialysis (also haemodialysis) is a method for removing waste products such as potassium and urea, as well as free water from the blood when the kidneys are in renal failure. Hemodialysis is one of three renal replacement therapies (the other two being renal transplant; peritoneal dialysis).
Hemodialysis can be an outpatient or inpatient therapy. Routine hemodialysis is conducted in a dialysis outpatient facility, either a purpose built room in a hospital or a dedicated, stand alone clinic. Less frequently hemodialysis is done at home. Dialysis treatments in a clinic are initiated and managed by specialized staff made up of nurses and technicians; dialysis treatments at home can be self initiated and managed or done jointly with the assistance of a trained helper who is usually a family member.
- Judith Z. Kallenbach. Review of hemodialysis for nurses and dialysis personnel. Elsevier Health Sciences. 2005. pp. 91
- National Kidney Foundation. Hemodialysis. accessdate 2011.