Diffusion

CLINICAL PEARLS:

  • During conventional intermittent hemodialysis, urea is mostly cleared by diffusion given its small solute size and high concentration gradient between blood and dialysate.
  • Drugs that have a molecular weight of <1000 Da have high water solubility and low protein binding in plasma are cleared well with hemodialysis. Lithium is one such drug. Hemodialysis is the treatment of choice for severe lithium toxicity.