Haemodialysis removes solutes by diffusion. As such, it is relatively inefficient for solutes of high molecular weight as clearance by diffusion is inversely related to the molecular weight of the solute.
Haemofiltration removes solutes by convection. As such, efficiency remains more constant for all solutes able to cross the semi-permeable membrane.
The choice between haemodialysis and haemofiltration can be difficult. Points in favour of haemofiltration include:
- better control of blood pressure
- less risk of hyperlipidaemia
Those in favour of haemodialysis:
- less expensive
- technically easier
- toxicity of molecules of high molecular weight has yet to be demonstrated
- haemofiltration can only reduce, not normalise, the concentration of larger solutes