What is the clearance test in peritoneal dialysis?

The clearance test in peritoneal dialysis measures how effectively that process is working. During peritoneal dialysis, a cleansing solution is infused into the abdomen of a person whose kidneys don't work, where it pulls wastes and extra fluids from the blood. The solution contains dextrose (or another sugar), salt and minerals dissolved in water. A catheter (soft tube) fills the abdomen with the solution. The solution mixes with wastes, salt and liquid, and all are removed when the solution drains out. This filling and removal process is called an exchange.

The clearance test involves studying waste solution samples from 24 hours, along with a blood sample taken during the same day. Doctors compare the levels of urea (urinary waste material) in the solution and in the blood to see how well it's being removed. If peritoneal dialysis isn't working effectively enough, doctors may:
  • increase the number of daily exchanges
  • increase the amount of peritoneal dialysis solution used in each exchange 
  • use solutions with higher dextrose concentrations

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