Hemodialysis is a procedure which enables the removal metabolic solute and fluid waste from the blood. The dialysis machine pumps blood through an extracorporeal circuit where it passes through a semi-permeable membrane called a dialyzer. Dissolved solutes like urea and other toxins, diffuse through the dialyzer membrane and out of the blood. The purified blood is then returned back to the patient. The duration of the dialysis treatment and amount of toxin removed is tailored to each patient and the severity of the patient's disease process.