Certified Hemodialysis Technician Practice Exam

The characteristic of a dialyzer that specifically explains the solute size that can pass through its membrane is the molecular weight cut off. This parameter indicates the maximum molecular weight of substances that the membrane can allow to pass through while retaining larger molecules. Dialyzers are designed with selective permeability based on the molecular weight of solutes, meaning that those below the cut-off threshold can diffuse across the membrane into the dialysate, while larger molecules are effectively blocked. While surface area and porosity also contribute to the overall efficiency and performance of the dialyzer, they do not directly define the size of solutes that can permeate the membrane. Surface area affects the total volume of fluid processed and the rate of solute exchange, while porosity describes the density and distribution of pores, influencing the flow rate but not specifically the allowed solute sizes. Volume refers to the overall capacity of the dialyzer but does not detail the size exclusion properties of the membrane itself. Thus, understanding molecular weight cut off allows you to predict and manage the removal of solutes during dialysis effectively.