Plasma exchange for myeloma kidney: cast(s) away?

Leung et al. (this issue) present a retrospective study of 40 patients. Observations in 14/40 led to the suggestion of restitution of plasma exchange for light-chain responsive, biopsy-proven myeloma kidney until a better randomized control trial (RCT) is constructed. A careful analysis of their study and a recent RCT suggest little difference in outcome between plasma exchange and control groups. The analysis supports restitution of a better RCT of plasma exchange for myeloma kidney rather than off-label use.