The intrinsic clearance of a hemodialyzer (mass transfer area coefficient, or K0A) can be calculated from in vitro data when the blood and dialysate flow rates are known. When the intrinsic clearance of the hemodialyzer is known, then the in vivo urea clearance can be calculated. The actual in vivo urea clearance is less than the theoretical clearance due to the need to correct for blood water content, cardiopulmonary recirculation, access recirculation and blood flow errors.
