Penicillamine nephropathy and iron.

7 of 16 patients with rheumatoid arthritis in whom penicillamine glomerulonephritis had developed had been taking oral iron, usually without the knowledge of their hospital clinician, while the dose of penicillamine was being gradually increased to an effective level. In 4 patients glomerulonephritis had appeared after the patients had stopped iron, with proteinuria developing with 2-5 months of discontinuation. Chelation of penicillamine by iron in the gut reduces its absorption, and in these 4 patients toxicity only became apparent after iron was stopped and there was a sudden increase in penicillamine absorption.