Dialyzer systems can consolidate multiple technologies and functionalities of blood treatment systems in a significantly integrated fashion. For example, this disclosure describes dialyzer systems that include a magnetically driven and magnetically levitating pump rotor integrated into the dialyzer. Such a dialyzer can be used with treatment modules that include a magnetic field-generating pump drive unit. In some embodiments, the dialyzers include pressure sensor chambers with flexible membranes with which corresponding pressure transducers of the treatment modules can interface to detect arterial and/or venous pressures.